DC-AC converter?

Question

Source:https://digital.wpi.edu/downloads/ns064789m?locale=zh page:15

Could someone tell me what component is this? ADC as a switch?! I am trying to build the 12 lead ECG circuit with Schematic symbols in Proteus 8

Answer 1

It's an SPDT switch used to remove (or integrate-out) DC offset voltages from the output of the INA321 when placed in the position shown. In the other position it just connects pin 5 (the instrumentation amplifier's reference pin) to 0 volts thus, leaving the DC output unaffected.