Signals or DC voltages for the reference voltage can be applied to the DYY-AMP-EVM through the test points labeled VREF. The following number correlates to the specific channel associated with the VREF pin. R_PL can be used to set the Vref pin to 0-V without the use of external connections. To set the VREF pin to GND, populate the respective pad with a 0 ohm resistor.