Full-wave synchronous detection circuit using analog switch IC

OP amplifier, 2 is a balanced output circuit that obtains positive and negative phase input H{.
It can also be replaced by a balanced transformer with a center tap, but in the low frequency range, it
is more advantageous to use an OP amplifier. Resistor R: The ratio to Ra is 1, and it is not necessarily limited to
lOkQt.
    In the circuit, the analog switch crCz) plays an important role. The contact position in the circuit diagram
connects the in-phase output (Ai output, that is, the positive half cycle of the input signal). On the inverting input of the OP amplifier, A3 is an inverting amplifier
with an amplification factor of I.
If the switch contact is switched downward, the inverting output (also output, the input signal
is a negative half cycle) is turned on (the same phase as REF, the Az output is positive), so an
inverting output port with an amplification factor of 1 can be obtained. Consider One input signal period,
■'the output terminal obtains a negative barrier wave output.