The VCA822 device is a DC-coupled, wideband, linear in V/V, continuously variable, voltage-controlled gain amplifier. It provides a differential input to single-ended conversion with a high-impedance gain control input used to vary the gain down 40dB from the nominal maximum gain set by the gain resistor (RG) and feedback resistor (RF).
The internal architecture of the VCA822 device 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 +100 V/V. Operating from ±5-V supplies, the gain control voltage for the VCA822 device 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 VCA822 device provides 10 V/V, at
1-V input, to 0.1 V/V at –1 V input of gain control range. The VCA822 device 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).
