VCA824

The VCA824 is a DC-coupled, wideband, linear-in V/V, continuously variable, voltage-controlled gain amplifier. The device provides a differential input to single-ended conversion with a high-impedance gain control input used to vary the gain down 40 dB from the nominal maximum gain set by the gain resistor (R_G) and feedback resistor (R_F).

The VCA824 internal architecture consists of two input buffers and an output current feedback amplifier stage integrated with a multiplier core to provide a complete variable gain amplifier (VGA) system that does not require external buffering. The maximum gain is set externally with two resistors, providing flexibility in designs. The maximum gain is intended to be set between 2 V/V and 40 V/V. Operating from ±5-V supplies, the gain control voltage for the VCA824 adjusts the gain linearly in V/V as the control voltage varies from 1 V to –1 V. For example, set for a maximum gain of 10 V/V, the VCA824 provides 10 V/V, at 1-V input, to 0.1 V/V at –1-V input of gain control range. The VCA824 offers excellent gain linearity. For a 20-dB maximum gain, and a gain-control input voltage varying between 0 V and 1 V, the gain does not deviate by more than ±0.3-dB (maximum at 25°C).