Compensating for the effects of round-trip delay in automatic test equipment

Improved pin electronics for automatic test equipment are disclosed which compensates for the effects of round-trip delay on signals transmitted by the pin electronics and a circuit under test along the same transmission line. The pin electronics includes a driver and comparator circuitry, both of which are coupled to a transmission line connecting the pin electronics to a node of the circuit under test. Signals produced by the pin electronics and the circuit under test are combined at the pin electronics due to the effects of round-trip delay between the pin electronics and the circuit under test. The comparator circuitry takes a scaled version of the signal produced by the pin electronics and subtracts it from the combined signal, thereby recovering the signal produced by the circuit under test. Other pin electronics are also disclosed that uses the scaled signal for modifying threshold voltages provided to the comparator circuitry, thereby facilitating measurement of the combined signal.