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general description the MAX2121 low-cost, direct-conversion tuner ic is designed for satellite set-top and vsat applications. the device directly converts the satellite signals from the lnb to baseband using a broadband i/q downcon- verter. the operating frequency range extends from 925mhz to 2175mhz. the device includes an lna and an rf variable-gain amplifier, i and q downconverting mixers, and base- band lowpass filters and digitally controlled baseband variable-gain amplifiers. together, the rf and base- band variable-gain amplifiers provide more than 80db of gain control range. the device includes fully monolithic vcos, as well as a complete fractional-n frequency synthesizer. additionally, an on-chip crystal oscillator is provided along with a buffered output for driving additional tuners and demodulators. synthesizer programming and device configuration are accomplished with a 2-wire serial inter- face. the ic features a vco autoselect (vas) function that automatically selects the proper vco. for multituner applications, the device can be configured to have one of two 2-wire interface addresses. a low-power standby mode is available whereupon the signal path is shut down while leaving the reference oscillator, digital inter- face, and buffer circuits active, providing a method to reduce power in single and multituner applications. the device is the most advanced broadband/vsat dbs tuner available. the low noise figure eliminates the need for an external lna. a small number of passive components are needed to form a complete broadband satellite tuner dvb-s2 rf front-end solution. the tuner is available in a very small, 5mm x 5mm, 28-pin thin qfn package. applications vsats features ? 925mhz to 2175mhz frequency range ? monolithic vco low phase noise: -97dbc/hz at 10khz no calibration required ? high dynamic range: -75dbm to 0dbm ? integrated lp filters: 123.75mhz ? single +3.3v ?% supply ? low-power standby mode ? address pin for multituner applications ? differential i/q interface ? i 2 c 2-wire serial interface ? very small, 5mm x 5mm, 28-pin tqfn package MAX2121 complete direct-conversion l-band tuner ________________________________________________________________ maxim integrated products 1 tunevco gndsyn cpout v cc_syn xtal bypvco scl v cc_bb qdc- addr qdc+ idc- rfin gc1 v cc_lo + iout+ qout- v cc_dig gndtune sda 19 17 16 3 5 18 4 6 v cc_vco refout 15 7 gnd iout- 20 2 v cc_rf1 21 idc+ 1 26 24 23 10 12 25 11 13 22 14 27 9 28 8 v cc_rf2 MAX2121 interface logic and control dc offset correction div2/div4 ep frequency synthesizer qout+ functional diagram ordering information 19-5959; rev 0; 6/11 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. * ep = exposed pad. + denotes a lead(pb)-free/rohs-compliant package. evaluation kit available part temp range pin-package MAX2121eti+ -40c to +85c 28 tqfn-ep*
MAX2121 complete direct-conversion l-band tuner 2 _______________________________________________________________________________________ absolute maximum ratings dc electrical characteristics (MAX2121 evaluation kit: v cc_ = +3.13v to +3.47v, f xtal = 27mhz, t a = -40? to +85?, v gc1 = +0.5v (max gain), default register settings except bbg[3:0] = 1011. no input signals at rf, baseband i/os are open circuited. typical values measured at v cc = +3.3v, t a = +25?, unless otherwise noted.) (note 1) stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. v cc_ to gnd .........................................................-0.3v to +3.9v all other pins to gnd.................................-0.3v to (v cc + 0.3v) rf input power: rfin .....................................................+10dbm bypvco, cpout, xtal, refout, iout_, qout_ , idc_, qdc_ to gnd short-circuit protection...............................10s continuous power dissipation (t a = +70?) tqfn (derate 34.5mw/? above +70?) ......................2.75w operating temperature range .............................-40? to +85? junction temperature ......................................................+150? storage temperature range .............................-65? to +160? lead temperature (soldering, 10s) .................................+300? soldering temperature (reflow) .......................................+260? parameter conditions min typ max units supply supply voltage (v cc_ ) 3.13 3.3 3.47 v receive mode, bit stby = 0 148 200 supply current standby mode, bit stby = 1 3 ma address select input (addr) digital input-voltage high, v ih 2.4 v digital input-voltage low, v il 0.5 v digital input-current high, i ih 50 a digital input-current low, i il -50 a analog gain-control input (gc1) input voltage range maximum gain = 0.5v 0.5 2.7 v input bias current -50 +50 a vco tuning voltage input (tunevco) input voltage range 0.4 2.3 v 2-wire serial inputs (scl, sda) clock frequency 400 khz input logic-level high 0.7 x v cc v input logic-level low 0.3 x v cc v input leakage current digital inputs = gnd or v cc 0.1 1 a 2-wire serial output (sda) output logic-level low i sink = 1ma (note 2) 0.4 v caution! esd sensitive device
MAX2121 complete direct-conversion l-band tuner _______________________________________________________________________________________ 3 parameter conditions min typ max units main signal path performance minimum gain f in = 2175mhz 72 78 db gain flatness 925mhz to 2175mhz (note 2) 4 6 db input frequency range (note 3) 925 2175 mhz rf gain-control range (gc1) 0.5v < v gc1 < 2.7v 65 73 db baseband gain-control range bits bbg[3:0] = 1111 to 0000 11.5 13.5 db in-band input ip3 (note 4) +2 dbm out-of-band input ip3 (note 5) +15 dbm input ip2 (note 6) +40 dbm v gc1 is set to 0.5v (maximum rf gain) and bbg[3:0] is adjusted to give a 1v p-p baseband output level for a -75dbm cw input tone at 1500mhz 8 noise figure starting with the same bbg[3:0] setting as above, v gc1 is adjusted to back off rf gain by 10db (note 2) 9 12 db minimum rf input return loss 925mhz < f rf < 2175mhz, in 75 system 12 db baseband output characteristics nominal output voltage swing r load = 200 //5pf 0.5 1 v p-p i/q amplitude imbalance measured at 500khz 1 db i/q quadrature phase imbalance measured at 500khz 3.5 degrees single-ended i/q output impedance real z o , from 1mhz to 140mhz 24 output 1db compression voltage differential 3 v p-p baseband highpass -3db frequency corner 47nf capacitors at idc_, qdc_ 400 hz baseband lowpass filters (5th-order butterworth with 1st-order gr oup delay compensation) filter bandwidth (-3db) 123.75 mhz rejection ratio at 247.5mhz 31 db group delay up to 0.5db bandwidth 1.0 ns 3db bandwidth tolerance 10 % frequency synthesizer rf-divider frequency range 925 2175 mhz rf-divider range (n) 19 251 reference-divider frequency range 12 30 mhz reference-divider range (r) 1 1 phase-detector comparison frequency 12 30 mhz ac electrical characteristics (MAX2121 evaluation kit: v cc = +3.13v to +3.47v, t a = -40? to +85?, default register settings except bbg[3:0] = 1111. typical values measured at v cc = +3.3v, t a = +25?, unless otherwise noted.) (note 1)
MAX2121 complete direct-conversion l-band tuner 4 _______________________________________________________________________________________ ac electrical characteristics (continued) (MAX2121 evaluation kit: v cc = +3.13v to +3.47v, t a = -40? to +85?, default register settings except bbg[3:0] = 1111. typical values measured at v cc = +3.3v, t a = +25?, unless otherwise noted.) (note 1) parameter conditions min typ max units voltage-controlled oscillator and lo generation guaranteed lo frequency range 925 2175 mhz f offset = 10khz -97 f offset = 100khz -100 lo phase noise f offset = 1mhz -122 dbc/hz xtal/reference oscillator input and output buffer xtal oscillator frequency range f xtal parallel-resonance-mode crystal (note 7) 12 30 mhz input overdrive level ac-coupled sine-wave input 0.5 1 2.0 v p-p xtal output-buffer divider range 1 8 xtal output voltage swing 12mhz to 30mhz, c load = 10pf 1 1.5 2 v p-p xtal output duty cycle 50 % note 1: min/max values are production tested at t a = +25?. min/max limits at t a = -40? and t a = +85? are guaranteed by design and characterization. note 2: guaranteed by design and characterization at t a = +25?. note 3: input gain range specifications met over this band. note 4: in-band iip3 test conditions: gc1 set to provide the nominal baseband output drive when mixing down a -23dbm tone at 2175mhz to 5mhz baseband (f lo = 2170mhz). baseband gain is set to its default value (bbg[3:0] = 1011). two tones at -26dbm each are applied at 1919mhz and 1663mhz. the im3 tone at 3mhz is measured at baseband, but is referred to the rf input. note 5: out-of-band iip3 test conditions: gc1 set to provide nominal baseband output drive when mixing down a -23dbm tone at 2175mhz to 5mhz baseband (f lo = 2170mhz). baseband gain is set to its default value (bbg[3:0] = 1011). two tones at -20dbm each are applied at 1919mhz and 1663mhz. the im3 tone at 5mhz is measured at baseband, but is referred to the rf input. note 6: input ip2 test conditions: gc1 set to provide nominal baseband output drive when mixing down a -23dbm tone at 2175mhz to 5mhz baseband (f lo = 2170mhz). baseband gain is set to its default value (bbg[3:0] = 1011). two tones at -20dbm each are applied at 925mhz and 1250mhz. the im2 tone at 5mhz is measured at baseband, but is referred to the rf input. note 7: see table 16 for crystal esr requirements.
MAX2121 complete direct-conversion l-band tuner _______________________________________________________________________________________ 5 typical operating characteristics (MAX2121 evaluation kit: v cc = +3.3v, t a = +25?, baseband output frequency = 5mhz, v gc1 = +1.2v, default register settings except bbg[3:0] = 1011, unless otherwise noted.) supply current vs. supply voltage MAX2121 toc01 supply voltage (v) supply current (ma) 3.4 3.3 3.2 130 135 140 145 150 155 160 165 170 175 125 3.1 3.5 t a = +85 c t a = +25 c t a = -40 c standby supply current vs. supply voltage MAX2121 toc02 supply voltage (v) standby supply current (ma) 3.4 3.3 3.2 1.5 2.0 2.5 3.0 1.0 3.1 3.5 t a = +85 c t a = -40 c hd3 vs. v out MAX2121 toc03 v out (v p-p ) baseband 3rd-order harmonic (dbc) 2.5 2.0 1.5 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -60 1.0 3.0 quadrature phase error vs. lo frequency MAX2121 toc04 lo frequency (mhz) quadrature phase error (deg) 1900 1650 1400 1150 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0 900 2150 f baseband = 50mhz t a = +85 c t a = +25 c t a = -40 c quadrature magnitude matching vs. lo frequency MAX2121 toc05 lo frequency (mhz) quadrature magnitude matching (db) 1900 1650 1400 1150 0.2 0.4 0.6 0.8 1.0 0 900 2150 f baseband = 50mhz t a = +85 c t a = +25 c t a = -40 c quadrature phase error vs. baseband frequency MAX2121 toc06 baseband frequency (mhz) quadrature phase error (deg) 10 1 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0 0.1 100 f lo = 1425mhz t a = +85 c t a = +25 c t a = -40 c quadrature magnitude matching vs. baseband frequency MAX2121 toc07 baseband frequency (mhz) quadrature magnitude matching (db) 10 1 0.2 0.4 0.6 0.8 1.0 0 0.1 100 f lo = 1425mhz t a = +85 c t a = +25 c t a = -40 c baseband filter frequency response MAX2121 toc08 baseband frequency (mhz) baseband output level (db) 400 300 200 100 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 -65 0 500 baseband filter frequency response MAX2121 toc09 baseband frequency (mhz) baseband output level (db) 125 100 75 50 25 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 -10 0 150 t a = +25 c
MAX2121 complete direct-conversion l-band tuner 6 _______________________________________________________________________________________ typical operating characteristics (continued) (MAX2121 evaluation kit: v cc = +3.3v, t a = +25?, baseband output frequency = 5mhz, v gc1 = +1.2v, default register settings except bbg[3:0] = 1011, unless otherwise noted.) baseband filter 3db frequency vs. temperature MAX2121 toc10 temperature ( c) baseband gain error at f-3db (db) 80 60 -20 0 20 40 -0.75 -0.50 -0.25 0 0.25 0.50 0.75 1.00 -1.00 -40 normalized at t a = +25 c baseband filter highpass frequency response MAX2121 toc11 baseband frequency (hz) baseband output level (db) 1000 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 -10 100 10,000 voltage gain vs. v gc1 MAX2121 toc12 v gc1 (v) voltage gain (db) 2.5 2.0 0.5 1.0 1.5 10 20 30 40 50 60 70 80 0 0 3.0 bbg[3:0] = 1111 noise figure vs. lo frequency (t a = +25 c) MAX2121 toc13 lo frequency (mhz) noise figure (db) 1900 1650 1150 1400 7.5 8.0 8.5 9.0 10.0 9.5 10.5 11.0 7.0 900 2150 adjust bbg[3:0] for 1v p-p baseband output with pin = -75dbm and v gc1 = 0.5v 10db backed off gain input return loss vs. frequency MAX2121 toc14 frequency (mhz) input return loss (db) 2025 1800 1350 1575 1125 -20 -15 -10 -5 0 -25 900 2250 v gc1 = 2.7v v gc1 = 0.5v phase noise at 10khz offset vs. channel frequency channel frequency (mhz) phase noise at 10khz offset (dbc/hz) MAX2121 toc15 925 1115 1305 1495 1685 1875 2065 2255 -105 -100 -95 -90 phase noise vs. offset frequency MAX2121 toc16 offset frequency (hz) phase noise (dbc/hz) 1.0e+05 1.0e+04 -120 -110 -100 -90 -130 1.0e+03 1.0e+06 f lo = 1800mhz lo leakage vs. lo frequency lo frequency (mhz) lo leakage (dbm) MAX2121 toc17 925 1175 1425 1675 1925 2175 -90 -85 -80 -75 -70 measured at rf input vco: kv vs. vtune vtune (v) kv (mhz/v) MAX2121 toc18 0 0.5 1.0 1.5 2.0 2.5 3.0 0 50 100 150 200 250 300 350 400 450 sub-band 23 sub-band 12 sub-band 0
MAX2121 complete direct-conversion l-band tuner _______________________________________________________________________________________ 7 pin description pin name function 1 v cc_rf2 dc power supply for lna. connect to a +3.3v low-noise supply. bypass to gnd with a 1nf capacitor connected as close as possible to the pin. do not share capacitor ground vias with other ground connections. 2 v cc_rf1 dc power supply for lna. connect to a +3.3v low-noise supply. bypass to gnd with a 1nf capacitor connected as close as possible to the pin. do not share capacitor ground vias with other ground connections. 3 gnd ground. connect to boards ground plane for proper operation. 4 rfin wideband 75 rf input. connect to an rf source through a dc-blocking capacitor. 5 gc1 rf gain-control input. high-impedance analog input with a 0.5v to 2.7v operating range. v gc1 = 0.5v corresponds to the maximum gain setting. 6 v cc_lo dc power supply for lo generation circuits. connect to a +3.3v low-noise supply. bypass to gnd with a 1nf capacitor connected as close as possible to the pin. do not share capacitor ground vias with other ground connections. 7 v cc_vco dc power supply for vco circuits. connect to a +3.3v low-noise supply. bypass to gnd with a 1nf capacitor connected as close as possible to the pin. do not share capacitor ground vias with other ground connections. tunevco gndsyn cpout v cc_syn xtal bypvco scl v cc_bb qdc- addr qdc+ idc- rfin gc1 v cc_lo + iout+ qout- v cc_dig gndtune sda 19 17 16 3 5 18 4 6 v cc_vco refout ep 15 7 gnd iout- 20 2 v cc_rf1 21 idc+ 1 26 24 23 10 12 25 11 13 22 14 27 9 28 8 v cc_rf2 MAX2121 qout+ tqfn (5mm x 5mm) top view pin configuration
MAX2121 complete direct-conversion l-band tuner 8 _______________________________________________________________________________________ pin name function 8 bypvco internal vco bias bypass. bypass to gnd with a 100nf capacitor connected as close as possible to the pin. do not share capacitor ground vias with other ground connections. 9 tunevco high-impedance vco tune input. connect the pll loop filter output directly to this pin with as short of a connection as possible. 10 gndtune ground for tunevco. connect to the pcb ground plane. 11 gndsyn ground for synthesizer. connect to the pcb ground plane. 12 cpout charge-pump output. connect this output to the pll loop filter input with the shortest connection possible. 13 v cc_syn dc power supply for synthesizer circuits. connect to a +3.3v low-noise supply. bypass to gnd with a 1nf capacitor connected as close as possible to the pin. do not share capacitor ground vias with other ground connections. 14 xtal crystal-oscillator interface. use with an external parallel-resonance-mode crystal through a series 1nf capacitor. see the typical application circuit . 15 refout crystal-oscillator buffer output. a dc-blocking capacitor must be used when driving external circuitry. 16 v cc_dig dc power supply for digital logic circuits. connect to a +3.3v low-noise supply. bypass to gnd with a 1nf capacitor connected as close as possible to the pin. do not share capacitor ground vias with other ground connections. 17 qout+ 18 qout- quadrature baseband differential output. ac-couple with 47nf capacitors to the demodulator input. 19 iout+ 20 iout- in-phase baseband differential output. ac-couple with 47nf capacitors to the demodulator input. 21 idc+ 22 idc- i-channel baseband dc offset correction. connect a 47nf ceramic chip capacitor from idc- to idc+. 23 qdc+ 24 qdc- q-channel baseband dc offset correction. connect a 47nf ceramic chip capacitor from qdc- to qdc+. 25 v cc_bb dc power supply for baseband circuits. connect to a +3.3v low-noise supply. bypass to gnd with a 1nf capacitor connected as close as possible to the pin. do not share capacitor ground vias with other ground connections. 26 sda 2-wire serial-data interface. requires 1k pullup resistor to v cc . 27 scl 2-wire serial-clock interface. requires 1k pullup resistor to v cc . 28 addr address. must be connected to either ground (logic 0) or supply (logic 1). ep exposed pad. solder evenly to the boards ground plane for proper operation. pin description (continued)
MAX2121 complete direct-conversion l-band tuner _______________________________________________________________________________________ 9 detailed description register description the MAX2121 includes 12 user-programmable registers and two read-only registers. see table 1 for register configurations. the register configuration of table 1 shows each bit name and the bit usage information for all registers. note that all registers must be written after and no earlier than 100? after the device is powered up. table 1. register configuration msb lsb data byte reg number register name read/ write reg address d[7] d[6] d[5] d[4] d[3] d[2] d[1] d[0] 1 n-divider msb write 0x00 frac 1 n[14] n[13] n[12] n[11] n[10] n[9] n[8] 2 n-divider lsb write 0x01 n[7] n[6] n[5] n[4] n[3] n[2] n[1] n[0] 3 charge pump write 0x02 cpmp[1] 0 cpmp[0] 0 cplin[1] 0 cplin[0] 1 f[19] f[18] f[17] f[16] 4 f-divider msb write 0x03 f[15] f[14] f[13] f[12] f[11] f[10] f[9] f[8] 5 f-divider lsb write 0x04 f[7] f[6] f[5] f[4] f[3] f[2] f[1] f[0] 6 xtal buffer and reference divider write 0x05 xd[2] xd[1] xd[0] r[4] r[3] r[2] r[1] r[0] 7 pll write 0x06 d24 cps icp x x x x x 8 vco write 0x07 vco[4] vco[3] vco[2] vco[1] vco[0] vas adl ade 9 lowpass filter write 0x08 10010111 10 control write 0x09 stby x pwdn 0 x bbg[3] bbg[2] bbg[1] bbg[0] 11 shutdown write 0x0a x pll 0 div 0 vco 0 bb 0 rfmix 0 rfvga 0 fe 0 12 test write 0x0b cptst[2] 0 cptst[1] 0 cptst[0] 0 x turbo 1 ld mux[2] 0 ld mux[1] 0 ld mux[0] 0 13 status byte-1 read 0x0c por vasa vase ld x x x x 14 status byte-2 read 0x0d vcosbr[4] vcosbr[3] vcosbr[2] vcosbr[1] vcosbr[0] adc[2] adc[1] adc[0] x = don? care. 0 = set to 0 for factory-tested operation. 1 = set to 1 for factory-tested operation.
MAX2121 complete direct-conversion l-band tuner 10 ______________________________________________________________________________________ table 2. n-divider msb register (address: 0x00) bit name bit location (0 = lsb) default function frac 7 1 users must program to 1 upon powering up the device. n[14:8] 6C0 0000000 sets the most significant bits of the pll integer-divide number (n). n can range from 19 to 251. table 3. n-divider lsb register (address: 0x01) bit name bit location (0 = lsb) default function n[7:0] 7C0 00100011 sets the least significant bits of the pll integer-divide number. n can range from 19 to 251. table 4. charge-pump register (address: 0x02) bit name bit location (0 = lsb) default function cpmp[1:0] 7C6 00 charge-pump minimum pulse width. users must program to 00 upon powering up the device. cplin[1:0] 5C4 00 controls charge-pump linearity. users must program to 01 upon powering up the device. f[19:16] 3C0 0010 sets the 4 most significant bits of the pll fractional divide number. default value is f = 194,180 decimal. table 5. f-divider msb register (address: 0x03) bit name bit location (0 = lsb) default function f[15:8] 7C0 11110110 sets the most significant bits of the pll fractional-divide number (f). default value is f = 194,180 decimal. table 6. f-divider lsb register (address: 0x04) bit name bit location (0 = lsb) default function f[7:0] 7C0 10000100 sets the least significant bits of the pll fractional-divide number (f). default value is f = 194,180 decimal. table 7. xtal buffer and reference divider register (address: 0x05) bit name bit location (0 = lsb) default function xd[2:0] 7C5 000 sets the crystal-divider setting. 000 = divide by 1. 001 = divide by 2. 011 = divide by 3. 100 = divide by 4. 101 through 110 = all divide values from 5 (101) to 7 (110). 111 = divide by 8. r[4:0] 4C0 00001 sets the pll reference-divider (r) number. users must program to 00001 upon powering up the device. 00001 = divide by 1; other values are not tested.
MAX2121 complete direct-conversion l-band tuner ______________________________________________________________________________________ 11 table 8. pll register (address: 0x06) bit name bit location (0 = lsb) default function d24 7 1 vco divider setting. 0 = divide by 2. use for lo frequencies 1125mhz. 1 = divide by 4. use for lo frequencies < 1125mhz. cps 6 1 charge-pump current mode. 0 = charge-pump current controlled by icp bit. 1 = charge-pump current controlled by vco autoselect (vas). icp 5 0 charge-pump current. 0 = 600a typical. 1 = 1200a typical. x 4C0 x dont care. table 9. vco register (address: 0x07) bit name bit location (0 = lsb) default function vco[4:0] 7C3 11001 controls which vco is activated when using manual vco programming mode. this also serves as the starting point for the vco autoselection (vas) mode. vas 2 1 vco autoselection (vas) circuit. 0 = disable vco selection must be programmed through i 2 c. 1 = enable vco selection controlled by autoselection circuit. adl 1 0 enables or disables the vco tuning voltage adc latch when the vco autoselect mode (vas) is disabled. 0 = disables the adc latch. 1 = latches the adc value. ade 0 0 enables or disables vco tuning voltage adc read when the vco autoselect mode (vas) is disabled. 0 = disables adc read. 1 = enables adc read. table 10. lowpass filter register (address: 0x08) bit name bit location (0 = lsb) default function reserved 7C0 01001011 user must program to 10010111 (97h) upon powering up the device.
MAX2121 complete direct-conversion l-band tuner 12 ______________________________________________________________________________________ table 11. control register (address: 0x09) bit name bit location (0 = lsb) default function stby 7 0 software standby control. 0 = normal operation. 1 = disables the signal path and frequency synthesizer leaving only the 2-wire bus, crystal oscillator, xtalout buffer, and xtalout buffer divider active. x 6 x dont care. pwdn 5 0 factory use only. 0 = normal operation; other value is not tested. x 4 x dont care. bbg[3:0] 3C0 0000 baseband gain setting (1db typical per step). 0000 = minimum gain (0db, default). 1111 = maximum gain (15db typical). table 12. shutdown register (address: 0x0a) bit name bit location (0 = lsb) default function x 7 x dont care. pll 6 0 pll enable. 0 = normal operation. 1 = shuts down the pll. value not tested. div 5 0 divider enable. 0 = normal operation. 1 = shuts down the divider. value not tested. vco 4 0 vco enable. 0 = normal operation. 1 = shuts down the vco. value not tested. bb 3 0 baseband enable. 0 = normal operation. 1 = shuts down the baseband. value not tested. rfmix 2 0 rf mixer enable. 0 = normal operation. 1 = shuts down the rf mixer. value not tested. rfvga 1 0 rf vga enable. 0 = normal operation. 1 = shuts down the rf vga. value not tested. fe 0 0 front-end enable. 0 = normal operation. 1 = shuts down the front-end. value not tested.
MAX2121 complete direct-conversion l-band tuner ______________________________________________________________________________________ 13 table 13. test register (address: 0x0b) bit name bit location (0 = lsb) default function cptst[2:0] 7C5 000 charge-pump test modes. 000 = normal operation (default). x 4 x dont care. turbo 3 1 charge-pump fast lock. users must program to 1 after powering up the device. ldmux[2:0] 2C0 000 refout output. 000 = normal operation; other values are not tested. table 14. status byte-1 register (address: 0x0c) bit name bit location (0 = lsb) function por 7 power-on reset status. 0 = chip status register has been read with a stop condition since last power-on. 1 = power-on reset (power cycle) has occurred. default values have been loaded in registers. vasa 6 indicates whether vco autoselection was successful. 0 = indicates the autoselect function is disabled or unsuccessful vco selection. 1 = indicates successful vco autoselection. vase 5 status indicator for the autoselect function. 0 = indicates the autoselect function is active. 1 = indicates the autoselect process is inactive. ld 4 pll lock detector. turbo bit must be programmed to 1 for valid ld reading. 0 = unlocked. 1 = locked. x 3C0 dont care. table 15. status byte-2 register (address: 0x0d) bit name bit location (0 = lsb) function vcosbr[4:0] 7C3 vco band readback. adc[2:0] 2C0 vas adc output readback. 000 = out of lock. 001 = locked. 010 = vas locked. 101 = vas locked. 110 = locked. 111 = out of lock.
MAX2121 complete direct-conversion l-band tuner 14 ______________________________________________________________________________________ 2-wire serial interface the MAX2121 uses a 2-wire i 2 c-compatible serial inter- face consisting of a serial-data line (sda) and a serial- clock line (scl). sda and scl facilitate bidirectional communication between the MAX2121 and the master at clock frequencies up to 400khz. the master initiates a data transfer on the bus and generates the scl sig- nal to permit data transfer. the MAX2121 behaves as a slave device that transfers and receives data to and from the master. sda and scl must be pulled high with external pullup resistors (1k or greater) for proper bus operation. pullup resistors should be referenced to the MAX2121? v cc . one bit is transferred during each scl clock cycle. a minimum of nine clock cycles is required to transfer a byte in or out of the MAX2121 (8 bits and an ack/nack). the data on sda must remain stable during the high period of the scl clock pulse. changes in sda while scl is high and stable are considered control signals (see the start and stop conditions section). both sda and scl remain high when the bus is not busy. start and stop conditions the master initiates a transmission with a start condi- tion (s), which is a high-to-low transition on sda while scl is high. the master terminates a transmission with a stop condition (p), which is a low-to-high transition on sda while scl is high. acknowledge and not-acknowledge conditions data transfers are framed with an acknowledge bit (ack) or a not-acknowledge bit (nack). both the mas- ter and the MAX2121 (slave) generate acknowledge bits. to generate an acknowledge, the receiving device must pull sda low before the rising edge of the acknowledge-related clock pulse (ninth pulse) and keep it low during the high period of the clock pulse. to generate a not-acknowledge condition, the receiver allows sda to be pulled high before the rising edge of the acknowledge-related clock pulse, and leaves sda high during the high period of the clock pulse. monitoring the acknowledge bits allows for detection of unsuccessful data transfers. an unsuccessful data transfer happens if a receiving device is busy or if a system fault has occurred. in the event of an unsuc- cessful data transfer, the bus master must reattempt communication at a later time. slave address the MAX2121 has a 7-bit slave address that must be sent to the device following a start condition to initi- ate communication. the slave address is internally pro- grammed to 1100000. the eighth bit (r/ w ) following the 7-bit address determines whether a read or write operation occurs. the MAX2121 continuously awaits a start condition followed by its slave address. when the device recog- nizes its slave address, it acknowledges by pulling the sda line low for one clock period; it is ready to accept or send data depending on the r/ w bit (figure 1). the write/read address is c0/c1 if addr pin is con- nected to ground. the write/read address is c2/c3 if the addr pin is connected to v cc . write cycle when addressed with a write command, the MAX2121 allows the master to write to a single register or to multi- ple successive registers. a write cycle begins with the bus master issuing a start condition followed by the seven slave address bits and a write bit (r/ w = 0). the MAX2121 issues an ack if the slave address byte is successfully received. the bus master must then send to the slave the address of the first register it wishes to write to (see table 1 for register addresses). if the slave acknowledges the address, the master can then write one byte to the regis- ter at the specified address. data is written beginning with the most significant bit. the MAX2121 again issues an ack if the data is successfully written to the register. the master can continue to write data to the successive internal registers with the MAX2121 acknowledging each successful transfer, or it can terminate transmission by issuing a stop condition. the write cycle does not termi- nate until the master issues a stop condition. scl 1 234567 1100000 89 r/w ack slave address s sda figure 1. MAX2121 slave address byte with addr pin connected to ground write device address r/w ack write register address ack write data to register 0x00 ack write data to register 0x01 ack write data to register 0x02 ack start 1100000 0 ? 0x00 ? 0x0e ? 0xd8 ? 0xe1 ? stop figure 2. example: write registers 0, 1, and 2 with 0x0e, 0xd8, and 0xe1, respectively.
MAX2121 complete direct-conversion l-band tuner ______________________________________________________________________________________ 15 read cycle when addressed with a read command, the MAX2121 allows the master to read back a single register, or mul- tiple successive registers. a read cycle begins with the bus master issuing a start condition followed by the seven slave address bits and a write bit (r/ w = 0). the MAX2121 issues an ack if the slave address byte is successfully received. the bus master must then send the address of the first register it wishes to read (see table 1 for register addresses). the slave acknowledges the address. then, a start condition is issued by the master, fol- lowed by the seven slave address bits and a read bit (r/ w = 1). the MAX2121 issues an ack if the slave address byte is successfully received. the MAX2121 starts sending data msb first with each scl clock cycle. at the 9th clock cycle, the master can issue an ack and continue to read successive registers, or the master can terminate the transmission by issuing a nack. the read cycle does not terminate until the mas- ter issues a stop condition. figure 3 illustrates an example in which registers 0, 1, and 2 are read back. application information the MAX2121 downconverts rf signals in the 925mhz to 2175mhz range directly to the baseband i/q signals. rf input the rf input of the MAX2121 is internally matched to 75 . only a dc-blocking capacitor is needed. see the typical application circuit . rf gain control the MAX2121 features a variable-gain low-noise ampli- fier providing 73db of rf gain range. the voltage con- trol (vgc) range is 0.5v (minimum attenuation) to 2.7v (maximum attenuation). baseband variable-gain amplifier the receiver baseband variable-gain amplifiers provide 15db of gain control range programmable in 1db steps. the vga gain can be serially programmed through the i 2 c interface by setting bits bbg[3:0] in the control register. baseband lowpass filter the MAX2121 includes an on-chip 5th-order butterworth filter with 1st-order group delay compensation. dc offset cancellation the dc offset cancellation is required to maintain the i/q output dynamic range. connecting an external capacitor between idc+ and idc- forms a highpass fil- ter for the i channel and an external capacitor between qdc+ and qdc- forms a highpass filter for the q chan- nel. keep the value of the external capacitor less than 47nf to form a typical highpass corner of 250hz. xtal oscillator the MAX2121 contains an internal reference oscillator, reference output divider, and output buffer. all that is required is to connect a crystal through a series 1nf capacitor. to minimize parasitics, place the crystal and series capacitor as close as possible to pin 14 (xtal). see table 16 for crystal (xtal) esr (equivalent series resistance) requirements. programming the fractional n- synthesizer the MAX2121 utilizes a fractional-n type synthesizer for lo frequency programming. to program the frequency synthesizer, the n and f values are encoded as straight binary numbers. determination of these values is illustrated by the following example: f lo is 2170mhz f xtal is 27 mhz phase-detector comparison frequency is from 12mhz and 30mhz r divider = r [ 4:0 ] = 1 f comp = 27mhz/1 = 27mhz d = f lo /f comp = 2170/27 = 80.37470 write device address ack read from status byte-1 register ack read from status byte-2 register ack/ nack start 1100000 1 ? ? ? ? ? stop r/w figure 3. example: receive data from read registers table 16. maximum crystal esr requirement esr max ( ) xtal frequency (mhz) 80 12 < f xtal 14 60 14 < f xtal 30
MAX2121 complete direct-conversion l-band tuner 16 ______________________________________________________________________________________ integer portion: n = 80 n [ 14:8 ] = 0 n [ 7:0 ] = 0101 0000 fractional portion: f = 0.370370 x 2 20 = 388,361 (round up the decimal portion) f = 0101 1110 1101 0000 1001 note: when changing lo frequencies, all the divider registers (integer and fractional) must be programmed to activate the vas function regardless of whether indi- vidual registers are changed. vco autoselect (vas) the MAX2121 includes 24 vcos. the local oscillator frequency can be manually selected by programming the vco[4:0] bits in the vco register. the selected vco is reported in the status byte-2 register (see table 15). alternatively, the MAX2121 can be set to autonomously choose a vco by setting the vas bit in the vco regis- ter to logic-high. the vas routine is initiated once the f-divider lsb register word (register 5) is loaded. in the event that only the n-divider register or f-divider msb word is changed, the f-divider lsb word must also be loaded last to initiate the vco autoselect function. the vco value programmed in the vco[4:0] register serves as the starting point for the auto- matic vco selection process. during the selection process, the vase bit in the status byte-1 register is cleared to indicate the autoselection function is active. upon successful completion, bits vase and vasa are set and the vco selected is reported in the status byte-2 register (see table 15). if the search is unsuccessful, vasa is cleared and vase is set. this indi- cates that searching has ended but no good vco has been found, and occurs when trying to tune to a frequen- cy outside the vco? specified frequency range. refer to application note 4256: extended characterization for the max2112/max2120 satellite tuners . 3-bit adc the MAX2121 has an internal 3-bit adc connected to the vco tune pin (tunevco). this adc can be used for checking the lock status of the vcos. table 17 summarizes the adc output bits and the vco lock indication. the vco autoselect routine only selects a vco in the ?as locked?range. this allows room for a vco to drift over temperature and remain in a valid ?ocked?range. the adc must first be enabled by setting the ade bit in the vco register. the adc reading is latched by a sub- sequent programming of the adc latch bit (adl = 1). the adc value is reported in the status byte-2 register (see table 15). standby mode the MAX2121 features normal operating mode and standby mode using the i 2 c interface. setting a logic- high to the stby bit in the control register puts the device into standby mode, during which only the 2- wire-compatible bus, the crystal oscillator, the xtal buffer, and the xtal buffer divider are active. in all cases, register settings loaded prior to entering shutdown are saved upon transition back to active mode. default register values are provided for the user? convenience only. it is the user? responsibility to load all the registers no sooner than 100? after the device is powered up. layout considerations the MAX2121 ev kit serves as a guide for pcb layout. keep rf signal lines as short as possible to minimize losses and radiation. use controlled impedance on all high-frequency traces. for proper operation, the exposed paddle must be soldered evenly to the board? ground plane. use abundant vias beneath the exposed paddle for maximum heat dissipation. use abundant ground vias between rf traces to minimize undesired coupling. bypass each v cc pin to ground with a 1nf capacitor placed as close as possible to the pin. table 17. adc trip points and lock status adc[2:0] lock status 000 out of lock 001 locked 010 vas locked 101 vas locked 110 locked 111 out of lock
MAX2121 complete direct-conversion l-band tuner ______________________________________________________________________________________ 17 tunevco gndsyn cpout v cc_syn xtal bypvco scl v cc_bb qdc- addr qdc+ idc- rfin gc1 v cc_lo + iout+ qout- v cc_dig gndtune sda 19 17 16 3 5 18 4 6 refout 15 7 v cc_rf1 iout- 20 2 v cc_rf2 21 idc+ 1 26 24 23 10 12 25 11 13 22 14 27 9 28 8 MAX2121 interface logic and control dc offset correction div2 /div4 ep frequency synthesizer qout+ v cc v cc v cc baseband outputs serial-clock input serial-data input/output v cc v gc v cc v cc gnd v cc_vco rf input v cc typical application circuit chip information process: bicmos package information for the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages . note that a ?? ?? or ??in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. package type package code outline no. land pattern no. 28 tqfn-ep t2855+3 21-0140 90-0023
MAX2121 complete direct-conversion l-band tuner maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. 18 ____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2011 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. revision history revision number revision date description pages changed 0 6/11 initial release

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