Patent ID: 7002435

Claim:
A variable capacitance circuit comprising: first to Nth variable capacitance elements sequentially connected in series between an input terminal and an output terminal, whose capacitances change depending on voltage applied thereto; an ith bias line on the input terminal side provided between an input terminal portion of the first variable capacitance element and a connection point between a 2ith variable capacitance element and a (2i+1)th variable capacitance element; and an ith bias line on the output terminal side provided between an output terminal portion of the Nth variable capacitance element and a connection point between a (2i−1)th variable capacitance element and the 2ith variable capacitance element, where N and i are integers satisfying N=2n+1, n≧1, 1≦i≦n, wherein the input terminal comprises a single input terminal that serves both as a signal input terminal for receiving radio frequency signals and an input terminal for application of direct current bias.