Switches and multiplexers are commonly used in the feedback path of amplifier circuits to provide configurable gain control. By using various resistor values on the switch path, the TMUX110x allows the system to have multiple gain settings. An external resistor ensures the amplifier is not operating in an open loop configuration. A transimpedance amplifier (TIA) for photodiode inputs is a common circuit that requires gain control using a switch to convert the output current of the photodiode into a voltage for the MCU or processor. The amount of light present during a photodiode measurement is dependent on the time of day and available light source. An external switch such as the TMUX110x can be utilized to increase the gain when a smaller photodiode current is present. The leakage current, capacitance, and charge injection performance of the TMUX110x are key specifications to evaluate when selecting a device for gain control. An example switched gain amplifier circuit is shown in Figure 9-4.

Figure 9-4 Configurable Gain Setting of a TIA Circuit