Production test costs for today's RF circuits are rapidly escalating. Two factors are responsible for this cost escalation: (a) the high cost of RF ATEs and (b) long test times required by elaborate performance tests. In this paper, we propose a framework for low- cost signature test of RF circuits using modulation of a baseband test signal and subsequent demodulation of the DUT response. The demodulated response of the DUT is used as a "signature" from which all the performance specifications are predicted. The applied test signal is optimized in such a way that the error between the measured DUT performances and the predicted DUT performances is minimized. The proposed low-cost solution can be easily built into a load board that can be interfaced to an inexpensive tester.