VARIABLE-CAPACITANCE DIODE

摘要

PROBLEM TO BE SOLVED: To provide a variable-capacitance diode wherein the relative varying width of its depleted layer to its voltage variation is reduced, and the linearity of its voltage-resonance frequency characteristic is improved largely within the scope of its using voltage. SOLUTION: The variable-capacitance diode is formed in a semiconductor substrate 1, and has an n-type impurity diffusing region 6 which constitutes a pn-junction together with a p-type impurity diffusing region 5. A capacitance C obtained when applying a reverse bias voltage (v) across electrodes 3, 4 of the variable-capacitance diode is represented by a function C(v) of the reverse bias voltage (v), and a resonance frequency (f) obtained at this time is represented by a function f(v) of the reverse bias voltage (v). Then, the variable-capacitance diode is such a diode that, when representing the function f(v) by the equation of f(v)=K'/√C, (K' is a constant), the difference of f'(v)=K/(1/√(C(v+0.05))-1/√(C(v-0.05))), (K is a constant), which is the difference of the function f(v) taken between v+0.05 and v-0.05 is forced to satisfy the equation of 0.95