Voltage variable capacitor tuning: A review

This paper discusses the history, device theory, characteristics, applications, and future trends of voltage varible capacitor tuning. All equations are stated in terms of two general exponents of power law functions, namely the impurity distribution proportional to x
^m
and the differential capacitance proportional to (V + V
0
)
^-n
. The role of these exponents is shown in the device theory, the temperature drift, linearity in a VCO, and the cross modulation in an FM modulator. Important results from many papers and reports are cited to reinforce the ideas presented. Throughout the review, the desirability of the exponent n = 2 is reiterated.