Considerations for Capacitance Measurements of Antenna Tuning RF Switches on Board

The subject of the paper is accurate measurements of the OFF-state shunt capacitance of antenna tuning RF switch ICs (integrated circuits) assembled on printed-circuit boards. According to the proposed method, an empty (open) instance of the test fixture on which the IC under test is populated is measured and included into the de-embedded procedure in addition to or instead of a nominal de-embedding structure. Such approach allows improving the absolute accuracy, repeatability and reproducibility of the shunt OFF-capacitance measurements. The experiment conducted on a designed shunt antenna tuning switch with the nominal capacitance value of 160 fF demonstrated the improvement in accuracy and repeatability by a factor of 2.3 with the proposed method comparing to the conventional common de-embedding approach.