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19-1825; Rev 0; 10/00
NUAL KIT MA ATION ET EVALU TA SHE WS DA FOLLO
2.4GHz Monolithic Voltage-Controlled Oscillators
Features
o Guaranteed Frequency Tuning Range MAX2750: 2400MHz to 2500MHz (Zero IF) MAX2751: 2120MHz to 2260MHz (240MHz to 280MHz IF) MAX2752: 2025MHz to 2165MHz (335MHz to 375MHz IF) o On-Chip Tank Circuit o Internally Matched Output Buffer Amplifier o Low-Current Shutdown Mode o +2.7V to +5.5V Supply Voltage Range o Miniature 8-Pin MAX Package
General Description
The MAX2750/MAX2751/MAX2752 are self-contained voltage-controlled oscillators (VCOs) intended for use in the 2.4GHz to 2.5GHz ISM band. Each IC combines a fully integrated oscillator and output buffer in a miniature 8-pin MAX package. The inductor and varactor elements of the tank are integrated on-chip, greatly simplifying application of the part. The only required external components are a couple of supply bypass capacitors. The IC provides direct connection to the VCO tuning voltage input and the VCO buffer output. The tuning voltage input range is +0.4V to +2.4V, and the oscillator frequency tuning range is factory adjusted to provide guaranteed limits. The output signal is buffered by an amplifier stage (internally matched to 50) to provide higher output power and isolate the device from load impedance variations. The MAX2750/MAX2751/MAX2752 operate over a +2.7V to +5.5V supply voltage range. Internal regulation of the oscillator supply voltage eliminates the need for an external LDO regulator for the VCO. The IC also provides a digitally controlled shutdown mode to permit implementation of sophisticated power-supply management. In shutdown, the supply current is reduced to less than 1A.
MAX2750/MAX2751/MAX2752
Ordering Information
PART MAX2750EUA MAX2751EUA MAX2752EUA TEMP. RANGE -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 8 MAX 8 MAX 8 MAX
________________________Applications
802.11b DSSS WLAN 802.11 FHSS WLAN Home RF 2.4GHz Bluetooth ISM Proprietary Radio
Pin Configuration appears at end of data sheet.
Typical Operating Circuit
BYP GND
TUNE
TUNE
OSCILLATOR CORE
OUT
OUT TO MIXER/ SYNTHESIZER
GND VCC1
SHDN
SHDN
MAX2750 MAX2751 MAX2752
BIAS
VCC VCC2
________________________________________________________________ Maxim Integrated Products
1
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
2.4GHz Monolithic Voltage-Controlled Oscillators MAX2750/MAX2751/MAX2752
ABSOLUTE MAXIMUM RATINGS
VCC to GND ..............................................................-0.3V to +6V TUNE, SHDN, BYP, OUT to GND ...............-0.3V to (VCC + 0.3V) Continuous Power Dissipation (TA = +70C) 8-Pin MAX (derate 5.7mW/C above TA = +70C).....457mW Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
DC ELECTRICAL CHARACTERISTICS
(VCC = +2.7V to +5.5V, VTUNE = +0.4V to +2.4V, V SHDN +2V, OUT = connected to 50 load, TA = -40C to +85C. Typical values are at VCC = +3.0V, TA = +25C, unless otherwise noted.) (Note 1)
PARAMETER Supply Voltage MAX2750 Supply Current MAX2751 MAX2752 Shutdown Supply Current SHDN Input Voltage Low SHDN Input Voltage High SHDN Input Current Low SHDN Input Current High TUNE Input Current V SHDN 0.6V V SHDN 2.0V 0.4 V TUNE 2.4V 2.0 -2 -2 0.02 2 2 TA = +25 C TA = -40oC to +85oC TA = +25oC TA = -40 C to +85 C TA = +25oC TA = -40oC to +85oC
o o o
CONDITIONS
MIN 2.7
TYP 11.3 14.1 9.7 12.7 10 12.8 0.2
MAX 5.5 14.4 17.0 12.1 15.9 12.1 15.2 1 0.6
UNITS V
mA
A V V A A nA
AC ELECTRICAL CHARACTERISTICS
(MAX2750/MAX2751/MAX2752 EV kit, VCC = +2.7V to +5.5V, VTUNE = +0.4V to +2.4V, V SHDN +2V, OUT = connected to 50 load, TA = +25C. Typical values are at VCC = +3.0V, unless otherwise noted.)
PARAMETER Oscillator Guaranteed Frequency Limits (Note1) CONDITIONS MAX2750 V TUNE = +0.4V to +2.4V, TA = -40oC to +85oC fOFFSET = 4MHz Noise floor MAX2750 Tuning Gain (Note 2) MAX2751 MAX2752 Output Power Return Loss Harmonics fOSC = 2400MHz, +3V fOSC = 2500MHz, +3V fOSC = 2120MHz, +3V fOSC = 2260MHz, +3V fOSC = 2025MHz, +3V fOSC = 2165MHz, +3V MAX2751 MAX2752 Phase Noise MIN 2400 2120 2025 -125 -151 140 90 175 110 170 105 -3 12 -30 dBm dB dBc MHz/V TYP MAX 2500 2260 2165 UNITS MHz MHz MHz dBc/Hz dBm/Hz
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2.4GHz Monolithic Voltage-Controlled Oscillators MAX2750/MAX2751/MAX2752
AC ELECTRICAL CHARACTERISTICS (continued)
(MAX2750/MAX2751/MAX2752 EV kit, VCC = +2.7V to +5.5V, VTUNE = +0.4V to +2.4V, V SHDN +2V, OUT = connected to 50 load, TA = +25C. Typical values are at VCC = +3.0V, unless otherwise noted.)
PARAMETER Load Pulling Supply Pushing Oscillator Turn-On Time (Note 3) Oscillator Turn-Off Time (Note 4) CONDITIONS VSWR = 2:1, all phases VCC stepped: +3.3V to +2.8V Exiting shutdown Entering shutdown MIN TYP 4 1.3 8 5 MAX UNITS MHzp-p MHz/V s s
Note 1: Note 2: Note 3: Note 4:
Specifications are production tested at TA = +25C. Limits over temperature are guaranteed by design and characterization. Tuning gain is measured at the oscillator's guaranteed frequency limits. Turn-on time to within 3dB of final output power Turn-off time to output power of -10dBm.
Typical Operating Characteristics
(Circuit of Figure 1, VCC = +3.0V, VTUNE = +0.4V to +2.4V, V SHDN 2V, TA = +25C, unless otherwise noted.)
MAX2750/MAX2751/MAX2752 SUPPLY CURRENT vs. TEMPERATURE
MAX2750/51/52 toc01
MAX2750/MAX2751/MAX2752 SHUTDOWN CURRENT vs. TEMPERATURE
MAX2750/51/52 toc02
MAX2750/MAX2751/MAX2752 TUNING CURRENT vs. TEMPERATURE
MAX2750/51/52 toc03
15 14 SUPPLY CURRENT (mA) 13 12 11 10 9 8 7 -40 -20 0 20 40 TEMPERATURE (C) 60 80 MAX2752 MAX2751 MAX2750
0.5
1.0
SHUTDOWN CURRENT (A)
TUNE INPUT CURRENT (nA)
0.4
0.8
0.3
0.6
0.2
0.4
0.1
0.2
0 -40 -20 0 20 40 60 80 TEMPERATURE (C)
0 -40 -20 0 20 40 60 80 TEMPERATURE (C)
MAX2750 VCO TUNING CURVE
MAX2750/51/52 toc04
MAX2751 VCO TUNING CURVE
MAX2750/51/52 toc05
MAX2752 VCO TUNING CURVE
2350 2250 TA = -40C 2150 2050 1950 1850
MAX2750/51/52 toc06
2600
2350 2250 2150 TA = +25C 2050 1950 TA = +85C TA = -40C
2500 FREQUENCY (MHz)
TA = -40C
FREQUENCY (MHz)
2400
TA = +25C
FREQUENCY (MHz)
2300
TA = +85C
TA = +25C TA = +85C
2200 0 0.5 1.0 1.5 VTUNE (V) 2.0 2.5 3.0
1850 0 0.5 1.0 1.5 VTUNE (V) 2.0 2.5 3.0
0
0.5
1.0
1.5 VTUNE (V)
2.0
2.5
3.0
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2.4GHz Monolithic Voltage-Controlled Oscillators MAX2750/MAX2751/MAX2752
Typical Operating Characteristics (continued)
(Circuit of Figure 1, VCC = +3.0V, VTUNE = +0.4V to +2.4V, V SHDN 2V, TA = +25C, unless otherwise noted.)
PHASE NOISE
MAX2750/51/52 toc07
MAX2751 OUTPUT POWER vs. TEMPERATURE
MAX2750/51/52 toc08
NORMALIZED HARMONIC OUTPUT SPECTRUM
MKR -30.00dB OUTPUT POWER (dBm)
MAX2750/51/52 toc09
-50 -60 -70 PHASE NOISE (dBc/Hz) -80 -90 -100 -110 -120 -130 -140 -150 0.1 1 OFFSET FREQUENCY (MHz)
-2
= 30dBc = 48dBc
OUTPUT POWER (dBm)
-3
-4
-5 10 -40 -20 0 20 40 60 80 TEMPERATURE (C) 0 -10 -20 OUTPUT POWER (dBm) -30 -40 -50 -60 -70 -80 -90 -100 0 2 4 6 8 10 12 14 16 18 20 0 2 4 6 8 4s
O
2O FREQUENCY
3O
OSCILLATOR TURN-ON TIME
-10 -20 OUTPUT POWER (dBm) -30 -40 -50 -60 -70 -80 -90 -100 TIME (s) 8s
MAX2750/51/52 toc10
OSCILLATOR TURN-ON TIME
MAX2750/51/52 toc11
0
10 12 14 16 18 20
TIME (s)
Pin Description
FUNCTION
PIN 1 2 3 4 5 6 7 8
NAME BYP TUNE GND SHDN VCC1 VCC2 OUT GND
VCO Bypass. Bypass with a 0.1F capacitor to GND. Oscillator Frequency Tuning Voltage Input. High-impedance input with a voltage input range of +0.4V (low frequency) to +2.4V (high frequency). Ground Connection for Oscillator and Biasing. Requires a low-inductance connection to the circuit board ground plane. Shutdown Logic Input. A high-impedance input logic level low disables the device and reduces supply current to less than 1.0A. A logic level high enables the device. Bias and Oscillator DC Supply Voltage Connection. Bypass separately from PIN6 with a 220pF capacitor to GND for low noise and low spurious content performance from the oscillator. Output Buffer DC Supply Voltage Connection. Bypass separately from PIN5 with a 220pF capacitor to GND for best high frequency performance. Buffered Oscillator Output. Incorporates an internal DC blocking capacitor. OUT is internally matched to 50. Ground Connection for Output Buffer. Requires a low-inductance connection to the circuit board ground plane.
4
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2.4GHz Monolithic Voltage-Controlled Oscillators MAX2750/MAX2751/MAX2752
BYP 0.1F
MAX2750 MAX2751 MAX2752
GND
FROM SYNTHESIZER LOOP FILTER
TUNE
OSCILLATOR CORE
OUT
OUT TO MIXER/ SYNTHESIZER
220pF VCC1 GND VCC SHDN SHDN BIAS VCC2 220pF
Figure 1. Typical Application Circuit
Detailed Description
Oscillator
The MAX2750/MAX2751/MAX2752 VCOs are implemented as an LC oscillator topology, integrating all of the tank components on-chip. This fully monolithic approach provides an extremely easy-to-use VCO, equivalent to a VCO module. The frequency is controlled by a voltage applied to the TUNE pin, which is internally connected to the varactor. The VCO core uses a differential topology to provide a stable frequency versus supply voltage and improve the immunity to load variations. In addition, there is a buffer amplifier following the oscillator core to provide added isolation from load variations and to boost the output power.
Applications Information
Tune Input
The tuning input is typically connected to the output of the PLL loop filter. The loop filter provides an appropriately low-impedance source. The input may incorporate an extra RC filter stage to reduce high-frequency noise and spurious signals. Any excess noise on the tuning input is directly translated into FM noise, which can degrade the phase-noise performance of the oscillator. Therefore, it is important to minimize the noise introduced on the tuning input. A simple RC filter with low corner frequency is needed during testing in order to filter the noise present on the voltage source driving the tuning line.
Output Buffer
The oscillator signal from the core drives an output buffer amplifier. The amplifier is internally matched to 50 including an on-chip DC blocking capacitor. No external DC blocking capacitor is required, eliminating the need for any external components. The output amplifier has its own VCC and GND pins to minimize load-pulling effects. The amplifier boosts the oscillator signal to a level suitable for driving most RF mixers.
Layout Issues
Always use controlled impedance lines (microstrip, coplanar waveguide, etc.) for high-frequency signals. Always place decoupling capacitors as close to the VCC pins as possible; for long VCC lines, it may be necessary to add additional decoupling capacitors located further from the device. Always provide a low-inductance path to ground, and keep GND vias as close to the device as possible. Thermal reliefs on GND pads are not recommended.
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2.4GHz Monolithic Voltage-Controlled Oscillators MAX2750/MAX2751/MAX2752
Pin Configuration
TOP VIEW
BYP TUNE GND 1 2 3 8 7 GND OUT VCC2 VCC1
Chip Information
TRANSISTOR COUNT: 176 PROCESS: BiPOLAR
MAX2750 MAX2751 MAX2752
6 5
SHDN 4
MAX
Package Information
8LUMAXD.EPS
6
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