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single-supply, high speed, fixed g = +2, rail-to-rail output video amplifier data sheet ada4856-3 rev. b document feedback information furnished by analog devices is believed to be accurate and reliable. however, no responsibility is assumed by analog devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. specifications subject to change without notice. no license is granted by implication or otherwise under any patent or patent rights of analog devices. trademarks and registered trademarks are the property of their respective owners. one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 781.329.4700 ?2008C2013 analog devices, inc. all rights reserved. technical support www.analog.com features voltage feedback architecture rail-to-rail output swing: 0.1 v to 4.9 v high speed amplifier ?3 db bandwidth: 225 mhz 0.1 db flatness at 2 v p-p: 74 mhz slew rate: 800 v/s settling time to 0.1% with 2 v step: 5 ns high input common-mode voltage range ?v s ? 0.2 v to +v s ? 1 v supply range: 3 v to 5.5 v differential gain error: 0.01% differential phase error: 0.01 low power 7.8 ma/amplifier typical supply current power-down feature available in 16-lead lfcsp applications professional video consumer video imaging instrumentation base stations active filters buffers connection diagram 1 2 + in2 nc pd nc 3 4 +in3 ?in3 out3 ?v s 5678 +in1 ?in1 out1 ?v s 16 15 14 13 11 out2 12 +v s 10 ?in2 9+v s 07686-001 notes 1. nc = no connect. 2. exposed pad connected to ?v s . ada4856-3 figure 1. general description the ada4856-3 (triple) is a fixed gain of +2, single-supply, rail- to-rail output video amplifier. it provides excellent video performance with 225 mhz, ?3 db bandwidth, 800 v/s slew rate, and 74 mhz, 0.1 db flatness into a 150 load. it has a wide input common-mode voltage range that extends 0.2 v below ground and 1 v below the positive rail. in addition, the output voltage swings within 200 mv of either supply, making this video amplifier easy to use on single-supply voltages as low as 3.3 v. the ada4856-3 offers a typical low power of 7.8 ma per amplifier, while being capable of delivering up to 52 ma of load current. it also features a power-down function for power sensitive applications that reduces the supply current to 1 ma. the ada4856-3 is available in a 16-lead lfcsp and is designed to work over the extended industrial temperature range of ?40c to +105c. 7 6 5 4 3 2 1 0 1 10 100 1000 closed-loop gain (db) frequency (mhz) 07686-058 v s = 3.3v, v out = 2v p-p v s = 5v, v out = 1.4v p-p v s = 5v, v out = 2v p-p r l = 150 ? v s = 3.3v, v out = 1.4v p-p figure 2. large signal frequency response
ada4856-3* product page quick links last content update: 11/01/2016 comparable parts view a parametric search of comparable parts evaluation kits ? ada4856-3 evaluation board documentation application notes ? an-402: replacing output clamping op amps with input clamping amps ? an-417: fast rail-to-rail operational amplifiers ease design constraints in low voltage high speed systems ? an-581: biasing and decoupling op amps in single supply applications data sheet ? ada4856-3: high speed, single-supply, fixed g = +2, rail-to-rail output video amplifier data sheet user guides ? ug-115: universal evaluation board for triple, high speed op amps offered in 16-lead, 4 mm 4 mm lfcsp packages tools and simulations ? power dissipation vs die temp ? vrms/dbm/dbu/dbv calculators reference materials tutorials ? mt-032: ideal voltage feedback (vfb) op amp ? mt-033: voltage feedback op amp gain and bandwidth ? mt-047: op amp noise ? mt-048: op amp noise relationships: 1/f noise, rms noise, and equivalent noise bandwidth ? mt-049: op amp total output noise calculations for single-pole system ? mt-050: op amp total output noise calculations for second-order system ? mt-052: op amp noise figure: don't be misled ? mt-053: op amp distortion: hd, thd, thd + n, imd, sfdr, mtpr ? mt-056: high speed voltage feedback op amps ? mt-058: effects of feedback capacitance on vfb and cfb op amps ? mt-059: compensating for the effects of input capacitance on vfb and cfb op amps used in current-to-voltage converters ? mt-060: choosing between voltage feedback and current feedback op amps design resources ? ada4856-3 material declaration ? pcn-pdn information ? quality and reliability ? symbols and footprints discussions view all ada4856-3 engineerzone discussions sample and buy visit the product page to see pricing options technical support submit a technical question or find your regional support number * this page was dynamically generated by analog devices, inc. and inserted into this data sheet. note: dynamic changes to the content on this page does not constitute a change to the revision number of the product data sheet. this content may be frequently modified.
ada4856- 3 data sheet rev. b | page 2 of 20 table of contents features .............................................................................................. 1 applications ....................................................................................... 1 connection diagram ....................................................................... 1 general description ......................................................................... 1 revision history ............................................................................... 2 specifications ..................................................................................... 3 5 v operation ............................................................................... 3 3.3 v operation ............................................................................ 4 absolute maximum ratings ............................................................ 5 thermal resistance ...................................................................... 5 maximum power dissipation ..................................................... 5 esd caution .................................................................................. 5 pin configuration and function descriptions ............................. 6 typica l performance characteristics ............................................. 7 theory of operation ...................................................................... 12 applications information .............................................................. 13 using the ada4856 - 3 in gains equal to +1, ?1 ........................ 13 using the ada4856 - 3 in gains equal to +3, +4, and +5 ..... 14 20 mhz active low - pass f ilter ................................................ 15 video line driver ....................................................................... 15 single - supply operation ........................................................... 16 power d own ................................................................................ 16 layout considerations ............................................................... 16 power supply bypassing ............................................................ 16 outlin e dimensions ....................................................................... 17 ordering guide .......................................................................... 17 revision history 3 /13 rev. a to rev. b changed package from cp - 16 - 14 to cp - 16- 23 (throughout) .... 1 updated outline dimensions ........................................................ 17 changes to ordering guide ............................................................. 7 1/09 rev. 0 to rev. a changes to figure 9 ........................................................................... 7 changes to figure 13, figure 15, and figure 16 ............................ 8 added figure 17 and figure 20; renumbered sequentially ........ 9 1 0 /08 revision 0: initial version
data sheet ada4856- 3 rev. b | page 3 of 20 specifications 5 v operation t a = 25c, + v s = 5 v, ?v s = 0 v, g = + 2, r l = 150 ? to midsupply , unless otherwise noted. table 1 . parameter test conditions min typ max unit dynamic performance ?3 db bandwidth v o = 0.1 v p -p 3 7 0 mhz v o = 1.4 v p -p 2 2 5 mhz v o = 2 v p -p 200 mhz bandwidth for 0.1 db flatness v o = 1.4 v p -p 90 mhz v o = 2 v p -p 74 mhz slew rate v o = 2 v step 800 v/s settling time to 0. 1% (rise/fall) v o = 2 v step 4.8/5.2 ns noise/distortion performance harmon ic distortion (hd2 / hd3) f c = 5 mhz, v o = 2 v p -p , r l = 1 k? ?92/?110 dbc f c = 20 mhz, v o = 2 v p -p , r l = 1 k? ?68/?71 dbc crosstalk, output to output f = 5 mhz ? 80 db input voltage noise f = 100 khz 14 nv/hz input current noise f = 100 khz 2 pa/hz differential gain error 0.01 % differential phase error 0.01 degrees dc performance input offset voltage 1 .3 3 .4 mv input offset voltage drift 5.5 v/c input bias current ?3.8 a input offset current 0.05 a closed - loop gain 1.95 2 2.05 v/v op en - loop gain 90 db input characteristics input resistance 3.2 m? input capacitance 0.5 pf input common - mode voltage range ? v s ? 0.2 + v s ? 1 v common - mode rejection ratio v cm = ? 0.2 v to +4 v 94 db output characteristics output voltage swing 0.1 to 4.9 v linear output current per amplifier hd2 ? 60 dbc, r l = 10 ? 5 2 ma power - down turn - on time 78 n s turn - off time 950 ns input bias current enabled 0.2 a powered d own ?125 a turn - on volta ge 3.75 v power supply operating range 3 5.5 v quiescent current per amplifier 7. 8 ma supply current w hen disabled 1 .1 ma power supply rejection ratio ?v s = 4.5 v to 5.5 v 96 db
ada4856- 3 data sheet rev. b | page 4 of 20 3.3 v operation t a = 25c, + v s = 3.3 v, ?v s = 0 v, g = + 2, r l = 150 ? to midsupply , unless otherwise noted. table 2 . p arameter test conditions min typ max unit dynamic performance ?3 db bandwidth v o = 0.1 v p -p 370 mhz v o = 2 v p -p 225 mhz bandwidth for 0.1 db flatness v o = 2 v p -p 77 mhz slew rate v o = 2 v step 800 v/s settling time to 0. 1% (rise/fall) v o = 2 v step 4.8/7 ns noise/distortion performance harmonic distortion (hd2 / hd3) f c = 5 mhz, v o = 1 v p - p, r l = 1 k? ?95/?128 dbc f c = 20 mhz, v o = 1 v p - p , r l = 1 k? ?74/?101 dbc crosstalk, output to output f = 5 mhz ? 78 db input voltage noise f = 100 khz 14 nv/hz input current noise f = 100 khz 2 pa/hz differential gain error 0.01 % differentia l phase error 0.01 degrees dc performance input offset voltage 1 .2 3 mv input offset voltage drift 5.5 v/c input bias current ?3.8 a input offset current 0.05 a closed - loop gain 1.95 2 2.05 v/v open - loop gain 90 db input characteristics input resistance 3.2 m? input capacitance 0.5 pf input common - mode voltage range ?v s ? 0.2 +v s ? 1 v common - mode rejection ratio v cm = ? 0.2 v to +2.3 v 94 db output characteristics output voltag e swing 0.1 to 3.22 v linear output current per amplifier hd2 ?60 dbc, r l = 10 ? 49 ma power - down turn - on time 78 ns turn - off time 950 ns turn - on voltage 2 .05 v power supply operating range 3 5.5 v quiescent cur rent per amplifier 7. 5 ma quiescent current w hen powered down 0.98 ma power supply rejection ratio ?v s = 2.97 v to 3.63 v 94 db
data sheet ada4856- 3 rev. b | page 5 of 20 absolute maximum rat ings table 3 . parameter rating supply voltage 6 v internal pow er dissipation 1 see figure 3 common - mode input voltage (?v s ? 0.2 v) to (+v s ? 1 v) differential input voltage v s output short - circuit duration observe power curves storage temperature range ?65 c to +125 c operating temp erature range ?40 c to +105 c lead temperature (soldering, 10 s ec ) 300c 1 specification is for device in free air. stresses above those listed under absolute maximum ratings may cause permanent damage to the device. this is a stress rating only; functio nal operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. thermal r esistance ja is specified for the worst - case conditions, that is, ja is spec i fied for a device soldered in a circuit board for surface - mount packages. table 4 . package type ja jc unit 16- lead lfcsp 67 17.5 c/w maximum power dissip at ion the maximum power that can be safely dissipated by the ad a4856 - 3 is limited by the associated rise in junction temperature. the maximum safe junction temperature for plastic encapsulated devices is determined by the glass transition temperature of the plastic, approximately 150 c . te mp ora r ily exceeding this limit may cause a shift in parametric performance due to a change in the stresses exerted on the die by the package. exceeding a junction temperature of 175 c for an extended period can result in dev ice failure. to ensure proper operation, it is necessary to observe the maximum power derating curves. 3.0 2.5 2.0 1.5 1.0 0.5 0 07686-103 maximum power dissipation (w) ambient temperature (c) ?40 ?30 ?20 ?10 10 20 30 40 50 60 70 80 90 100 0 figure 3 . maximum power dissipation vs. ambient temperature esd caution
ada4856-3 data sheet rev. b | page 6 of 20 pin configuration and fu nction descriptions pd 07686-003 notes 1. nc = no connect. 2. exposed pad connected to ?v s . 12 11 10 1 3 4 9 2 6 5 7 8 1 6 1 5 1 4 1 3 nc +in2 nc +v s ?v s out1 ?in1 +in1 out2 ?in2 +v s +in3 ?in3 out3 ?v s ada4856-3 top view figure 4. pin configuration table 5. pin function descriptions pin no. mnemonic description 1 nc no connect. 2 +in2 noninverting input 2. 3 nc no connect. 4 pd power down. 5 +in3 noninverting input 3. 6 ?in3 inverting input 3. 7 out3 output 3. 8 ?v s negative supply. 9 +v s positive supply. 10 ?in2 inverting input 2. 11 out2 output 2. 12 +v s positive supply. 13 ?v s negative supply. 14 out1 output 1. 15 ?in1 inverting input 1. 16 +in1 noninverting input 1. 17 (epad) exposed pad (epad) the ex posed pad must be connected to ?v s .
data sheet ada4856- 3 rev. b | page 7 of 20 typical performance characteristics t a = 25c, +v s = 5 v, g = + 2, r l = 150 ?, large signal v out = 2 v p - p , small signal v out = 100 mv p - p, unless o therwise noted. 7 6 5 4 3 2 1 0 1 10 100 1000 closed-loop gain (db) f r e q u e nc y ( m h z ) v s = 5v v s = 3.3v 07686-005 figure 5 . small signal frequency response vs. supply voltage 6.2 6.1 6.0 5.9 5.8 1 10 100 1000 closed-loop gain (db) f r e q u e nc y ( m h z ) 07686-006 v s = 5v, v out = 2v p-p v s = 3.3v, v out = 1.4v p-p v s = 3.3v, v out = 2v p-p v s = 5v, v out = 1.4v p-p figure 6. l a rge signal 0.1 db flatness vs. supply voltage 7 6 5 4 3 2 1 0 1 10 100 1000 closed-loop gain (db) f r e q u e nc y ( m h z ) 07686-007 r l = 150? r l = 1k? figure 7 . small signal frequency response vs. load resistance 7 6 5 4 3 2 1 0 1 10 100 1000 closed-loop gain (db) f re q ue nc y ( m hz ) 07686-008 v s = 3.3v, v out = 2v p-p v s = 5v, v out = 1.4v p-p v s = 5v, v out = 2v p-p v s = 3.3v, v out = 1.4v p-p figure 8 . large signal frequency response vs. supply voltage ?8 ?6 ?4 ?2 0 2 1 10 100 1000 closed-loop gain (db) frequency (mhz) t a = +25c t a = +85c t a = +105c t a = ?40c 07686-009 t a = +25c t a = +85c t a = +105c t a = ? 40c figure 9. small signal frequency response vs. temperature 6 4 2 0 ?2 ?4 ?6 1 10 100 1000 closed-loop gain (db) frequency (mhz) 07686-010 c l = 4.4pf c l = 6.6pf c l = 2.2pf figure 10 . small signal frequency response vs. capacitive load
ada4856-3 data sheet rev. b | page 8 of 20 ? 50 ?60 ?70 ?80 ?90 ?100 ?110 ?120 ?130 ?140 0.1110 hd2 hd3 100 distortion (dbc) frequency (mhz) 07686-011 r l = 1k ? v out = 2v p-p figure 11. harmonic distortion vs. frequency 0 ?20 ?40 ?60 ?80 ?100 ?120 0.1 1 10 100 1000 forward isolation (db) frequency (mhz) 07686-012 out2 out3 out1 figure 12. forward isolation vs. frequency 0 ?10 ?20 ?30 ?40 ?50 ?60 ?70 ?80 ?90 ?100 0.01 100 600 10 1 0.1 psrr (db) frequency (mhz) 07686-013 +psrr ?psrr figure 13. power supply rejectio n ratio (psrr) vs. frequency ? 50 ?60 ?70 ?80 ?90 ?100 ?110 ?120 ?130 ?140 0.1 1 hd2 hd3 10 100 distortion (dbc) frequency (mhz) 07686-014 r l = 1k ? v out = 1v p-p v s = 3.3v figure 14. harmonic distortion vs. frequency ?120 ?110 ?100 ?90 ?80 ?70 ?60 ?50 ?40 ?30 ?20 ? 10 1 10 100 500 all hostile crosstalk (db) frequency (mhz) 07686-015 in1, in2, out3 in2, in3, out1 in1, in3, out2 figure 15. crosstalk vs. frequency 07685-024 time (2ns/div) settling time (%) 0.5 0.4 0.3 0.2 0.1 0 ?0.1 ?0.2 ?0.3 ?0.4 ?0.5 input output error figure 16. settling time
data sheet ada4856- 3 rev. b | page 9 of 20 10 100 1k 10 100 1k 10k 100k 07686-117 1m voltage noise (nv/hz) f r equ enc y ( hz ) figure 17 . output voltage noise vs. frequency ?0.04 ?0.06 ?0.02 0 0.02 0.04 0.06 output voltage (v) time (10ns/div) 07686-018 v s = 3.3v v s = 5v figure 18 . small signal transi ent response vs. supply voltage 0.08 0.06 0.04 0.02 0 ?0.02 ?0.04 ?0.06 ?0.08 output voltage (v) time (10ns/div) 07686-019 c l = 2.2pf c l = 4.4pf c l = 6.6pf figure 19 . small signal transient response vs. capacitive load cur r e n t n o i s e (p a / hz) 1 10 100 10 100 1k 10k 100k 1m f r eq u enc y ( h z ) 07686-120 figure 20 . output current noise vs. frequency ?1.0 ?1.5 ?0.5 0 0.5 1.0 1.5 output voltage (v) time (10ns/div) 07686-021 v s = 3.3v v s = 5v figure 21 . large signal transien t response vs. supply voltage 1.5 1.0 0.5 0 ?0.5 ?1.0 ?1.5 output voltage (v) time (10ns/div) 07686-022 c l = 2.2pf c l = 4.4pf c l = 6.6pf figure 22 . large signal transient response vs. capacitive load
ada4856- 3 data sheet rev. b | page 10 of 20 0.08 0.06 0.04 0.02 0 ?0.02 ?0.04 ?0.06 ?0.08 output voltage (v) time (10ns/div) 07686-023 c l = 2.2pf c l = 4.4pf c l = 6.6pf v s = 3.3v figure 23 . small signal transient response vs. capacitive load 4 3 2 1 0 ?1 ?2 ?3 ?4 voltage (v) time (50ns/div) 07686-025 2 v in v out figure 24 . output overdrive recovery 3.0 2.5 v pd v out 2.0 1.5 1.0 0.5 0 ?0.5 ?1.0 ?1.5 voltage (v) time (1us/div) 07686-056 figure 25 . turn - on/turn - off time 1.5 1.0 0.5 0 ?0.5 ?1.0 ?1.5 output voltage (v) time (10ns/div) 07686-026 c l = 2.2pf c l = 4.4pf c l = 6.6pf v s = 3.3v figure 26 . large signal tr ansient response vs. capacitive load 2.5 2.0 1.5 1.0 0.5 0 ?0.5 ?1.0 ?1.5 ?2.0 ?2.5 voltage (v) time (50ns/div) 07686-028 2 v in v out v s = 3.3v figure 27 . output overdrive recovery 23.6 23.4 23.0 22.6 23.2 22.8 22.2 22.4 22.0 ?40 ?25 ?10 5 20 temper a ture (c) quiescent current (ma) 35 65 80 1 10 125 50 95 21.8 07686-132 v s = 5v v s = 3.3v figure 28 . quiescent current vs. temperature
data sheet ada4856- 3 rev. b | page 11 of 20 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 ?40 ?20 0 20 40 60 80 100 120 offset voltage (mv) temperature (c) 07686-034 figure 29 . offset drift vs. temperature 0.01 0.1 1 10 100 100k 1m 10m 100m 1g output impedence (?) frequency (hz) 07686-135 f igure 30 . output impedance vs. frequency 5.00 4.95 4.90 4.85 4.80 4.75 4.70 4.65 4.60 0.01 0.1 1 10 100 saturation voltage (mv) load current (ma) 07686-038 figure 31 . output saturation voltage vs. load current 25.0 24.5 24.0 23.5 23.0 22.5 22.0 2.7 3.0 3.3 3.6 3.9 4.2 4.5 4.8 5.1 5.4 quiescent current (ma) supply voltage (v) 07686-057 figure 32 . quiescent current vs. supply voltage
ada4856- 3 data sheet rev. b | page 12 of 20 theory o f operation the ada485 6 - 3 is a voltage feedback op amp that employs a new input stage that achieves a high slew rate while maintaining a wide common - mode input range . the input common - mode range of the ada485 6 - 3 extends from 200 mv below the negative rail to about 1 v from the positive rail . this feature makes the ada485 6 - 3 ideal for low voltage single - supply applications . in addition , this new input stage does not sacrifice noise performance for slew rate. at 14 nv/hz, the ada485 6 - 3 is one of the lowest noise rail - to - rail out put video amp lifier s in the market. besides a novel input stage, the ada485 6 - 3 employs the analog devices, inc., patented rail - to - rail output stage . this output stage makes an efficient use of the power supplies , allowing the op amp to drive up to three video loads to within 3 0 0 mv from both rails . in addition , this output stage provides the amplifier with very fast overdrive characteristics, an important property in video applications. the ada485 6 - 3 comes in a 16 - lead lfcsp that has an exposed th ermal pad for lower operating temperature. this pad is connected internally to the negative rail. to avoid printed circuit b oard (pcb) layout problems, the ada485 6 - 3 features a new pin out flow that is optimized for video applications . as shown in figure 4 , th e feedback and gain resistor s are on - chip , which minimize s the number of component s needed and improves the design layout. the ada485 6 - 3 is fabricated in analog devices dielectrically isolated extra fast complementary bipola r 3 (xfcb3) process, which results in the outstanding speed and dynamic range displayed by the amplifier. out +in ?in c c 1 ?v s g m1 g m2 +v s r 07686-147 figure 33 . high level design schematic
data sheet ada4856-3 rev. b | page 13 of 20 applications information using the ada4856-3 in gains equal to +1, ?1 the ada4856-3 was designed to offer outstanding video performance, simplify applications, and minimize board area. the ada4856-3 is a triple amplifier with on-chip feedback and gain set resistors. the gain is fixed internally at g = +2. the inclusion of the on-chip resistors not only simplifies the design of the application but also eliminates six surface-mount resistors, saving valuable board space and lowering assembly costs. whereas the ada4856-3 has a fixed gain of g = +2, it can be used in other gain configurations, such as g = ?1 and g = +1. unity-gain operation option 1 there are two options for obtaining unity gain (g = +1). the first is shown in figure 34. in this configuration, the Cin input pin is tied to the output (feedback is now provided with the two internal 402 resistors in parallel), and the input is applied to the noninverting input. the noise gain for this configuration is 1. 07686-032 0.1f 0.1f v in r t v out + v s ?v s gain of +1 10f 10f figure 34. unity gain of option 1 option 2 another option exists for running the ada4856-3 as a unity- gain amplifier. in this configuration, the noise gain is +2, see figure 35. the frequency response and transient response for this configuration closely match the gain of +2 plots because the noise gains are equal. this method does have twice the noise gain of option 1; however, in applications that do not require low noise, option 2 offers less peaking and ringing. by tying the inputs together, the net gain of the amplifier becomes 1. equation 1 shows the transfer characteristic for the schematic shown in figure 35. ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? g g f in g f in out r rr v r r vv (1) which simplifies to v out = v in . 0.1f 0.1f v in r t r g r f v out + v s ?v s gain of +1 07686-030 10f 10f figure 35. unity gain of option 2 inverting unity-gain operation in this configuration, the noninverting input is tied to ground and the input signal is applied to the inverting input. the noise gain for this configuration is +2, see figure 36. 0.1f 0.1f v in r t v out + v s ?v s gain of ?1 07686-031 10f 10f figure 36. inverting configuration (g = ?1) figure 37 shows the small signal frequency response for both gain of +1 (option 1 and option 2) and gain of ?1 configurations. it is clear that g = +1, option 2 has better flatness and no peaking compared to option 1. 6 3 0 ?3 ?6 ?9 ?12 1 10 100 1000 magnitude (db) frequency (mhz) 07686-044 v s = 5v r l = 100 ? v out = 100mv p-p option 1 g = +1 option 2 g = +1 g = ?1 figure 37. g = +1 and g = ?1
ada4856- 3 data sheet rev. b | page 14 of 20 using the ada4856 - 3 in gains equal to + 3, +4 , and +5 depending on certain applications, it might be useful to have a fixed gain amplifier that can provide various gains. the advant age of having a fixed gain amplifier is the ease of layout, the reduced number of component s needed , and the matching of the gain and feedback resistor s. gain of + 3 configuration figure 38 shows the ada4856 - 3 used as a n amplifi er with a fixed gain of + 3. n o external resistors are required, just a simple trace connecting certain inputs and outputs. connect v in to u1, which is set to a gain of +2, and u2 , which is set to unity. u3 then takes the output of u1 and gains it up by +2 and subtract s the output of u2 to produce v out . as shown in figure 41, the large signal frequency response for g = +3 is flat out to 65 mhz , with a bandwidth of 165 mhz, a 2 v p - p output voltage , and a 100 ? load. ada4856-3 07686-045 pd 16 15 14 13 5 6 7 12 11 10 9 1 2 3 4 0 . 1 f 0 . 1 f 0 . 1 f 10 f 0 . 1 f + 10 f + ? v s ? v s + v s + v s v o u t v in 8 figure 38 . gain of + 3 gain of + 4 configuration to get a gain of +4, set one amplifier to a gain of +1 and set the other two amplifiers to a gain of +2. figure 39 shows v in going in u2 at unity, then u1 takes the ou tput of u2 and gains it by +2 , and then feed s it to u3 , which also gains it by +2 to produce v out . ada4856-3 07686-046 pd 16 15 14 13 5 6 7 12 11 10 9 1 2 3 4 0 . 1 f 0 . 1 f 0 . 1 f 10 f 0 . 1 f + 10 f + ? v s ? v s + v s + v s v o u t v in 8 figure 39 . gain of + 4 as shown in figure 41 , the large signal frequency response for g = +4 is also flat out to 65 mhz , and it has a bandwidth of 180 mhz . gain of + 5 configuration t he gain of +5 is very similar to the g = +3 configuration but with u2 set to a gain of ? 1, which ends up being added to twice the output of u1 to generate v out w ith g = +5. ada4856-3 07686-047 pd 16 15 14 13 5 6 7 12 11 10 9 1 2 3 4 0 . 1 f 0 . 1 f 0 . 1 f 10 f 0 . 1 f + 10 f + ? v s ? v s + v s + v s v o u t v in 8 figure 40 . gain of + 5 figure 41 shows the large signal frequency response of the three closed - loop gain sets (+3, +4, and +5) with flatness that extends to 65 mhz and a ? 3 db bandwidth of 190 mhz. ?18 ?15 ?12 ?9 ?6 ?3 0 3 6 9 12 15 1 10 100 1000 closed-loop gain (db) frequency (mhz) g = +5 g = +4 g = +3 07686-048 r l = 100? v s = 5v v out = 2v p-p fi gure 41 . large signal frequency response for all th ree gains
data sheet ada4856- 3 rev. b | page 15 of 20 20 mh z active low - pass filter the ada4856 - 3 triple amplifier lends itself to higher order active filters. figure 42 shows a 20 mhz, 6 - pole, sallen - key low - pass filter. v in u1 op amp out1 + ? r1 93.1 r2 604 c2 22pf c1 33pf u2 op amp out2 + ? r3 113? r4 732? c4 15pf c3 33pf u3 op amp out3 + ? r5 121? r6 475? c6 15pf c5 47pf 07686-049 v out figure 42 . 20 mhz, 6 - pole low - pass filter the filter has a gain of approximately 18 db , which is set by three fixed gain of 2 stages , and a flat frequency response out to 14 mhz. this type of filter is commonly used at the output of a video dac as a reconstruction filter. the frequency response of the filter is shown in figure 43. 20 10 0 ?10 ?20 ?30 ?40 ?50 ?60 1 10 100 200 magnitude (db) frequency (mhz) 07686-050 six poles two poles four poles figure 43 . 20 mhz , low - pass filter frequency response vide o line driver the ada48 56 - 3 was designed to excel in video driver applications. figure 44 shows a typical schematic for a video driver operating on bipolar supplies. 1 2 3 ada4856-3 07686-051 pd 0 . 1 f 0 . 1 f 0 . 1 f 0 . 1 f 10 f 0 . 1 f + 0 . 1 f 10 f + 7 5? 7 5? 7 5? 7 5? 7 5? 7 5? ? v s ? v s + v s + v s v o u t ( r ) v in ( r ) v in (g) v in (b) v o u t (g) v o u t (b) 16 15 14 13 5 6 7 12 11 10 9 4 8 figure 44 . video driver schematic in applications that require multiple video loads be driven simultaneously, the ada48 56- 3 can deliver. figure 45 shows the ada48 56- 3 configured with triple video loads. figure 46 shows the triple vide o load performance. 07686-052 75 cable 75 cable 75 75 75 v out 2 v out 1 ?v s +v s v in 0.1f 0.1f 10f 10f 75 cable 75 75 75 cable 75 75 v out 3 + ? ada4856-3 0.1f figure 45 . video driver schematic for t riple video loads 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 1 10 100 200 magnitude (db) frequency (mhz) 07686-053 r l = 150? r l = 75? r l = 50? v s = 5v v out = 1v p-p figure 46 . large signal frequency response for various loads
ada4856-3 data sheet rev. b | page 16 of 20 single-supply operation the ada4856-3 can operate in single-supply applications. figure 47 shows the schematic for a single 5 v supply video driver. resistors r2 and r4 establish the midsupply reference. capacitor c2 is the bypass capacitor for the midsupply reference. capacitor c1 is the input coupling capacitor, and c6 is the output coupling capacitor. capacitor c5 prevents constant current from being drawn through the internal gain set resistor. resistor r3 sets the ac input impedance of the circuit. for more information on single-supply operation of op amps, see avoiding op-amp instability problems in single-supply applications, analog dialogue, volume 35, number 2, march- may, 2001, at www.analog.com . c2 1f r2 50k? r4 50k? r3 1k? c1 22f r1 50 ? c6 220f r5 75 ? r6 75 ? c5 22f ada4856-3 +5v 07686-035 v out v in ?v s c3 2.2f c4 0.01f +5 v figure 47. ac-coupled, single-s upply video driver schematic in addition, the ada4856-3 can be configured in dc-coupled, single-supply operation. the common-mode input voltage can go about 200 mv below ground, which makes it a true single- supply part. however, in video applications, the black level is set at 0 v, which means that the output of the amplifier must go to the ground level as well. this part has a rail-to-rail output stage; it can go as close as 100 mv from either rail. figure 48 shows the schematic for adding 50 mv dc offset to the input signal so that the output is not clipped while still properly terminating the input with 75 . 07686-156 r1 3.74k ? u1 r2 76.8 ? r3 75? r4 75? ada4856-3 5v v out v in ?v s c1 10f c2 0.1f 5 v figure 48. dc-coupled single supply video driver schematic power down the ada4856-3 is equipped with a pd (power-down) pin for all three amplifiers. this allows the user to reduce the quiescent supply current when an amplifier is inactive. the power-down threshold levels are derived from the voltage applied to the +v s pin. when used in single-supply applications, this is especially useful with conventional logic levels . the amplifier is enabled when the voltage applied to the pd pin is greater than +v s ? 1.25 v. in a 5 v single-supply application, the typical threshold voltage is +3.75 v, and in a 3.3 v dual-supply application, the typical threshold voltage is +2 v. the amplifier is also enabled when the pd pin is left floating (not connected). however, the amplifier is powered down when the voltage on the pd pin is lower than 2.5 v from +v s . if the pd pin is not used, it is best to connect it to the positive supply table 6. power-down voltage control pd pin 5 v 2.5 v 3.3 v not active >3.75 v >1.25 v >2.05 v active <2 v <0 v <1.3 v layout considerations as is the case with all high speed applications, careful attention to printed circuit board (pcb) layout details prevents associated board parasitics from becoming problematic. proper rf design technique is mandatory. the pcb should have a ground plane covering all unused portions of the component side of the board to provide a low impedance return path. removing the ground plane on all layers from the area near the input and output pins reduces stray capacitance. locate termination resistors and loads as close as possible to their respective inputs and outputs. keep input and output traces as far apart as possible to minimize coupling (crosstalk) though the board. adherence to microstrip or stripline design techniques for long signal traces (greater than about 1 inch) is recommended. power supply bypassing careful attention must be paid to bypassing the power supply pins of the ada4856-3. use high quality capacitors with low equivalent series resistance (esr), such as multilayer ceramic capacitors (mlccs), to minimize supply voltage ripple and power dissipation. a large, usually tantalum, 10 f to 47 f capacitor located in proximity to the ada4856-3 is required to provide good decoupling for lower frequency signals. in addition, locate 0.1 f mlcc decoupling capacitors as close to each of the power supply pins as is physically possible, no more than 1/8 inch away. the ground returns should terminate immediately into the ground plane. locating the bypass capacitor return close to the load return minimizes ground loops and improves performance.
data sheet ada4856-3 rev. b | page 17 of 20 outline dimensions compliant to jedec standards mo-220-wggc. 111908-a 1 0.65 bsc bottom view top view 16 5 8 9 12 13 4 exposed pad p i n 1 i n d i c a t o r 4.10 4.00 sq 3.90 0.70 0.60 0.50 seating plane 0.80 0.75 0.70 0.05 max 0.02 nom 0.20 ref 0.25 min coplanarity 0.08 pin 1 indi c ator 0.35 0.30 0.25 2.25 2.10 sq 1.95 for proper connection of the exposed pad, refer to the pin configuration and function descriptions section of this data sheet. figure 49.16-lead lead frame chip scale package [lfcsp_wq] 4 mm 4 mm body, very very thin quad (cp-16-23) dimensions shown in millimeters ordering guide model 1 temperature range package description package option ordering quantity ada4856-3ycpz-r2 C40c to +105c 16-lead lfcsp_wq cp-16-23 250 ada4856-3ycpz-r7 C40c to +105c 16-lead lfcsp_wq cp-16-23 1,500 ada4856-3ycpz-rl C40c to +105c 16-lead lfcsp_wq cp-16-23 5,000 ADA4856-3YCP-EBZ evaluation board 1 z = rohs compliant part.
ada4856- 3 data sheet rev. b | page 18 of 20 notes
data sheet ada4856- 3 rev. b | page 19 of 20 notes
ada4856- 3 data sheet rev. b | page 20 of 20 notes ? 20 08 C 2013 analog devices, inc. all rights reserved. trademarks and registered trademarks are the property of their respective owners. d07686 - 0- 3/13(b)

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