Evaluation of high quality varactor diodes

Recent measurement procedures used between 1 Mc/s and 40 Gc/s in evaluating very high cut-off frequency varactor diodes are discussed. The types of measurement are: bridge measurements at low frequencies, microwave coaxial line measurements, a transmission method near the diode series-resonant frequency, and a transmission method at diode parallel resonance. Typical results from each type of measurement are given. The effect of bias on the parameters of the simple equivalent circuit is described. Correlation of data from the four types of measurement has shown that the simple equivalent circuit does not describe the diode completely. Modification is necessary to take into account the effect at the junction of stray capacitance. Some attempt is made to relate parametric amplifier performance to the results of diode measurements.