Voltage-controlled Amplifier
The inputs are ac-coupled to minimize DC offset errors. The 18 kΩ resistors must be matched to within 0.1% to achieve > 55 dB CMR. The VCONTROL pin has a gain control range of -1.3V (40 dB) to 4V (-100 dB) and a slope of -30 mV/dB. The application circuit shows a 3 kΩ and 1 kΩ resistor divider from a control voltage. The choice of these resistors is arbitrary and could be any values to properly scale the control voltage. In fact, these resistors can be omitted if the control voltage has been properly scaled. The 1 µF capacitor is in place to provide some filtering of the control signal.
