Op amp linearizes attenuator control response

摘要

Professional-audio equipment commonly uses Analog Devices' (www.analog.com) high-performance, quad-voltage-controlled SSM2164 attenuator. The control response is -30 dB/V, with 0V producing unity gain. Attenuation increases as the applied control voltage increases in the positive direction. The circuit in Figure 1 extends the range of applications for this versatile chip by providing a simple means of linearizing the control response. The result is an amplifier with gain directly proportional to the control voltage. In addition, the circuit also functions as a simple logarithm generator.