Switches and multiplexers are commonly used in the feedback path of the amplifier circuits to provide configurable gain control. By using various resistor values on each switch path, the TMUX622x allows the system to have multiple gain settings. An external resistor causes the amplifier to not operate in an open loop configuration and gives up to 4 gain settings. The leakage current, on-resistance, and charge injection performance of the TMUX622x are key specifications to evaluate when selecting a device for gain control.

Figure 8-1 shows the TMUX622x configured to select the gain of an op-amp, creating a discrete PGA.

For more information on how to use TI's analog switches in Discrete Programmable Gain Amplifier (PGA) such as the impact of On-Capacitance, see Choosing the Right Multiplexer for a Discrete Programmable Gain Amplifier (PGA)

Figure 8-1 Gain Switching