This document details the design of a low-cost, two-chip voltage-controlled amplifier (VCA) and video switch. The design utilizes the AD539JN analog multiplier in conjunction with the 5539N wideband operational amplifier to achieve a 50MHz bandwidth while meeting stringent differential phase and gain requirements. The combination allows the system to drive a 75-ohm terminated coaxial cable directly.
| Bandwidth | 50MHz |
|---|---|
| Signal Input Range | + 2V |
| Control Input Range | zero to + 3V FS |
| Total Gain Range | 100dB |
| Total Harmonic Distortion | less than 0.05% |
The circuit uses the AD539JN analog multiplier and the 5539N wideband op-amp.
The maximum gain is about 4.3dB when pin 9 is connected to the op-amp output.