A probe card assembly includes a printed circuit board with tester contacts for making electrical connections to a semiconductor tester. The probe card assembly also includes a probe head assembly with probes for contacting a semiconductor device under test. One or more daughter cards is mounted to the printed circuit board such that they are substantially coplanar with the printed circuit board. The daughter cards may contain a circuit for processing test data, including test signals to be input into the semiconductor and/or response signals generated by the semiconductor device in response to the test signals.