The application shown in Figure 8-1 demonstrates how to toggle between the DAC output and low signal voltage for control of a GaN power amplifier using a single control input. The DAC output is utilized to bias the gate of the power amplifier and can be disconnected from the circuit using the select pin of the switch. The TMUX7219 can support 1.8 V logic signals on the control input, allowing the device to interface with low logic controls of an FPGA or MCU. The TMUX7219 can operate without any external components except for the supply decoupling capacitors. The select pin has an internal pull-down resistor to prevent floating input logic. All inputs to the switch must fall within the recommended operating conditions of the TMUX7219 including signal range and continuous current. For this design with a positive supply of 8 V on V_DD and negative supply of −12 V on V_SS, the signal range can be 8 V to −12 V. The maximum continuous current (I_DC) can be up to 440 mA for a wide-range current measurement (for more information, refer to Recommended Operating Conditions).