Abstract: A mode selection amplifier circuit has multiple differential amplifier circuits coupled to receive input signals A, B and C. Each differential amplifier circuit is selectively operable for generating a signal output representative of an output mode with the output mode of each differential amplifier circuit selected from one of algebraic combinations of the signal inputs A?C, B?C, A?B and (A+B)/2?C. The mode selection amplifier circuit is usable in a signal acquisition probe for providing various signal output modes to a measurement test instrument.