Investigation of Intermodulation in a Tuning Varactor

2nd and 3rd order intermodulation distortions of a tuning varactor are analyzed by using nonlinear parameters P2 and ¢3 which are determined by the measured values of the diode capacitance. The calculated values by using ¢agree quite well with the experimental results for actual diodes. In addition, the methods of compensating the distortion by a fixed capacitor or another diode with appropriately divided bias voltage are discussed and it is shown that the nonlinearity is compensated even in the case of n greater than 0.5. These methods are particularly effective for a circuit with greater Q.