Amplifier and Data Converter Selection Guide
Amplifier and Data Converter Selection Guide
Amplifier and Data Converter Selection Guide
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14 <strong>Amplifier</strong>s<br />
➔<br />
High-Speed <strong>Amplifier</strong>s<br />
TI develops high-speed signal conditioning<br />
products using state-of-the-art processes that<br />
give leading-edge performance. Used in<br />
high-speed signal chains <strong>and</strong> analog-to-digital<br />
drive circuits, high-speed amps are broadly<br />
defined as any amplifier having at least<br />
50MHz of b<strong>and</strong>width <strong>and</strong> at least 100V/µs<br />
slew rate. High-speed amps from TI come in<br />
several different types <strong>and</strong> supply<br />
voltage options.<br />
Design Considerations<br />
Voltage-feedback type—the most<br />
commonly used amp <strong>and</strong> the basic building<br />
block of most analog signal chains such as<br />
gain blocks, filtering, level shifting, buffering,<br />
etc. Most voltage-feedback amps are unitygain<br />
stable, though some are decompensated<br />
to provide wider b<strong>and</strong>width, faster slew rate<br />
<strong>and</strong> lower noise.<br />
Current-feedback type—most commonly<br />
seen in video or DSL line driver applications, or<br />
designs where extremely fast slew rate<br />
is needed.<br />
Fully differential amplifier (FDA)—the fully<br />
differential input <strong>and</strong> output topology has the<br />
primary benefit of reducing even order<br />
harmonics, thereby reducing total harmonic<br />
distortion. The FDA also rejects common-mode<br />
components in the signal <strong>and</strong> provides a larger<br />
output swing to the load relative to singleended<br />
amplifiers. Fully differential amplifiers<br />
are well-suited to driving analog-to-digital<br />
converters. A V COM pin sets the output<br />
common-mode voltage required by newer,<br />
single-supply, ADCs.<br />
FET-Input (or CMOS) amplifiers—have higher<br />
input impedance than typical bipolar amps<br />
<strong>and</strong> are more useful to interfacing to high<br />
impedance sources, such as photodiodes in<br />
transimpedance circuits.<br />
Video amplifiers—can be used in a<br />
number of different ways, but generally are<br />
in the signal path for amplifying, buffering,<br />
filtering or driving video lines. The specifications<br />
of most interest are differential gain<br />
<strong>and</strong> differential phase. Current-feedback<br />
amps are typically used in video applications,<br />
because of their combination of high slew<br />
rate <strong>and</strong> excellent output drive at low<br />
quiescent power.<br />
Fixed <strong>and</strong> variable gain—these amps have<br />
either a fixed gain, or a variable gain that can<br />
be set either digitally with a few control pins,<br />
or linearly with a control voltage. Fixed-gain<br />
amplifiers are fixed internally with gain<br />
setting resistors. Variable gain amplifiers can<br />
have different gain ranges, <strong>and</strong> can also be<br />
differential input <strong>and</strong>/or output.<br />
Packaging—high-speed amplifiers typically<br />
come in surface-mount packages, because<br />
parasitics of DIP packages can limit performance.<br />
Industry st<strong>and</strong>ard surface-mount<br />
packages (SOIC, MSOP, TSSOP, QFN <strong>and</strong> SOT23)<br />
h<strong>and</strong>le the highest speed requirements. For<br />
b<strong>and</strong>widths approaching 1GHz <strong>and</strong><br />
higher, the QFN package decreases<br />
inductance <strong>and</strong> capacitance.<br />
Evaluation boards—high-speed amps have an<br />
associated fully populated Evaluation Module<br />
(EVM) or an unpopulated printed circuit board<br />
(PCB). EVMs are a very important part of<br />
high-speed amplifier evaluation, since layout is<br />
critical to design success. To make layout<br />
simple, Gerber files for the EVMs are available.<br />
See page 101 for more information.<br />
Voltage Feedback<br />
Current Feedback<br />
High-Speed < 500MHz (GBW Product)<br />
FET or CMOS Input<br />
Low Noise ≤ 3nV/ Hz<br />
General Purpose<br />
+5V to ±5V Operational<br />
OPA656<br />
OPA657 (G > 7)<br />
OPA355/2355/3355<br />
OPA356/2356<br />
OPA354/2354/4354<br />
OPA357/2357<br />
OPA358/OPA360/OPA361<br />
OPA300/OPA2300<br />
OPA301/OPA2301<br />
THS4631<br />
OPAy380/OPA2380<br />
THS4031/4032 (G ≥ 2)<br />
OPA2822<br />
THS4130/4131<br />
THS4271<br />
OPA300/OPA301<br />
OPA820/OPA4820<br />
OPA842<br />
OPA843 (G > 3)<br />
OPA846/OPA2846 (G > 7)<br />
OPA847 (G > 12)<br />
OPA358<br />
OPA820/OPA4820<br />
OPA683/2683<br />
OPA684/2684/3684/4684<br />
OPA691/2691/3691<br />
OPA692/3692 (G = 2 or ±1)<br />
OPA2677<br />
THS3201/02<br />
OPA694/OPA2694<br />
THS4001<br />
THS4011/4012<br />
THS4051/4052<br />
THS4081/4082<br />
THS4041/4042<br />
OPA820/OPA4820<br />
OPA2613<br />
OPA2614<br />
OPA842<br />
OPA2652<br />
OPA2822<br />
THS4271<br />
OPA690/2690/3690<br />
OPAy890<br />
Fully Differential<br />
THS4120/4121<br />
THS4130/4131<br />
THS4140/4141<br />
THS4500/4501<br />
THS4502/4503<br />
THS4509<br />
THS4508<br />
THS4511<br />
THS4513<br />
THS4520<br />
Low Voltage ≤ 3.3V<br />
THS4120/21<br />
OPA355/2355/3355<br />
OPA356/2356<br />
THS4222/4226<br />
OPA354/2354/4354<br />
OPA357/2357<br />
OPA300/OPA2300<br />
OPA301/OPA2301<br />
OPA358/OPA360/OPA361<br />
OPA830/OPA2830<br />
OPA832/OPA2832<br />
Variable <strong>and</strong> Fixed Gain<br />
THS7530<br />
VCA2612/2613/2614/2616/2618<br />
VCA810<br />
VCA8613/VCA8617<br />
VCA2615/VCA2617<br />
OPA860<br />
OPA861<br />
BUF602<br />
BUF634<br />
OPA615<br />
General Purpose<br />
±5V to ±15V Operational<br />
THS3112/15<br />
THS3122/25<br />
THS3110/11<br />
THS3120/1<br />
THS3091/95<br />
THS3092/96<br />
THS6184<br />
Very High-Speed > 500MHz (GBW Products) Rail-to-Rail Input or Output<br />
OPA843<br />
OPA847<br />
OPA846/OPA2846<br />
THS4271<br />
THS4302<br />
High-speed amplifiers selection tree.<br />
OPA355/2355/3355<br />
OPA356/2356<br />
THS4222/4226<br />
OPA354/2354/4354<br />
OPA357/2357<br />
OPA358/OPA360<br />
OPA830/OPA2830/OPA4830<br />
OPA832/OPA2832<br />
Voltage Limiting Output<br />
OPA698<br />
OPA699 (G ≥ 4)<br />
Very High-Speed > 500MHz<br />
OPA695<br />
THS3201/THS3202<br />
OPA694/OPA2694<br />
Preview devices appear in BLUE.<br />
New devices appear in RED.<br />
<strong>Amplifier</strong> <strong>and</strong> <strong>Data</strong> <strong>Converter</strong> <strong>Selection</strong> <strong>Guide</strong> Texas Instruments 3Q 2006
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