A bias circuit selects the second external input voltage or voltage obtained by adding {HEAD ~ bias voltage} to the second external input voltage, according to {TAIL ~ the output voltage} of the amplifying circuit, and outputs it as the voltage corresponding to second external input voltage 
A bias circuit selects the second external input voltage or voltage obtained by adding { HEAD ~ bias voltage } to the second external input voltage , according to { TAIL ~ the output voltage } of the amplifying circuit , and outputs it as the voltage corresponding to second external input voltage
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH