Distortion in variable-capacitance diodes

Distortion in variable-capacitance diodes is analyzed using the Volterra series approach. Closed-form expressions for intermodulation distortion produced by variable-capacitance diodes in series- and parallel-tuned circuits are derived and verified by experiment at frequencies up to 200 MHz. The choice of the diode capacitance law exponent for minimum distortion is investigated. Distortion in multiple-diode connections is analyzed and the advantages of the back-to-back connection is shown. Calculation shows the elimination of third-order distortion for n=0.5 in this connection.