That THAT1570高性能电流反馈放大方案

That 公司的THAT1570是多用途高性能电流反馈放大器,适合用于差分麦克风前置放大器和总线加法应用.增益调整采用三个外接电阻来实现,范围从0到60dB. 工作电压±5V 到±18V,工作电流7.5mA,60 dB增益的输入噪音为1 nV/√Hz, 30 dB增益的THD+N为0.0003%.本文介绍THAT1570主要特性,方框图,以及多种应用电路.

The THAT1570 is a versatile, high performance current-feedback amplifier suitable for differential microphone preamp and bus summing applications. The IC comes in a small QFN package, which saves PCB space over discrete and other integrated solutions.

Gain is adjusted via three external resistors (RA, RB, and RG), making it possible to optimize noise over a wide range of gains. The 1570 supports the traditional approach to gain control (viz., THATs 1510 or 1512) by fixing RA and RB, and varying RG to control gain. However, the 1570 also supports varying all three resistors simultaneously with a dual-gang potentiometer or a switched resistor network. This flexible approach enables the designer to optimize noise over a wider range of gains than is possible with fixed RA and RB.

The 1570s differential output simplifies connection to differential input devices such as A/D converters. The part operates from as little as ±5V up through ±18V supplies. Running on ±18V supplies, at unity gain, the part accepts >+28dBu input signals.

The 1570 is designed to mate perfectly with THAT’s 5171 Digital Preamplifier Controller IC. The part-pair comprises an optimized, digitally controlled audio preamplifier.

Designed from the ground up in THATs complementary bipolar dielectric-isolation process and including laser-trimmed Si-Chrome thin-film resistors, the 1570 improves on existing integrated microphone preamps by offering more versatile gain configuration,lower noise at low gains, higher slew rate, and lower distortion.

THAT1570 主要特性:

Low Noise:

1 nV/√Hz input noise (60 dB gain)

Low THD+N:

0.0003% ≤30 dB gain

0.0008% @ 40 dB gain

Low Current: 7.5 mA typ

Wide Bandwidth: 4.2MHz @40dB gain

High Slew Rate: 53 V/us

Wide Signal Swing: >28.7dBu (±18V supplies)

Gain adjustable from 0 to >60 dB

Differential output

Small 4 x 4mm QFN16 package

Mates with THAT5171 Digital Preamplifier Controller IC

THAT1570 应用:

Microphone Preamplifiers

Digitally-Controlled Microphone Preamplifiers

Differential Low-Noise Preamplifiers

Differential Summing Amplifiers
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Differential Variable-Gain Amplifiers
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Moving-Coil Transducer Amplifiers

Line Input Stages

Audio

Sonar

Instrumentation

图1.THAT1570 方框图

图2. 采用单轴增益控制的THAT1570应用电路

图3. 采用双轴增益控制的THAT1570应用电路

图4. 采用单轴增益控制,AC耦合RG的THAT1570应用电路

图5. 采用双轴增益控制,AC耦合RG的THAT1570应用电路

图6. 采用单轴增益控制,AC耦合RG的THAT1570 Phantom功率应用电路

图6. 采用双轴增益控制,AC耦合RG的THAT1570 Phantom功率应用电路