In standard instrumentation amplifier, there are a three op-amps instrumentation amplifier circuit is common, but if you wanted a smaller component count and lower cost instrumentations, you can use two op-amp for the same functions: a high impedance and good CMRR for sensor pre-amplification and buffering. The figure is show the circuit.

The circuit is a simplest form of the op-amps instrumentation amplifier circuit. A two-op-amp instrumentation amplifier can also be used to make a high-input impedance DC differential amplifier. As in the two-op-amp circuit, this instrumentation amplifier requires precise resistor matching for good CMRR. R4 should equal to R1 and R3 should equal R2.

The circuit is a simplest form of the op-amps instrumentation amplifier circuit. A two-op-amp instrumentation amplifier can also be used to make a high-input impedance DC differential amplifier. As in the two-op-amp circuit, this instrumentation amplifier requires precise resistor matching for good CMRR. R4 should equal to R1 and R3 should equal R2.