Patent ID: 7898351

Claim:
A modulation circuit comprising: a sampling unit that over-samples an input digital signal input on a basis of a multiplying clock signal obtained by multiplying a reference clock, and outputs an over-sampled first over-sampling signal; a first frequency conversion unit that performs frequency conversion of the first over-sampling signal based on the first over-sampling signal and a reference signal having a predetermined phase, and outputs a first high-frequency signal; a first filter unit that delays the first over-sampling signal by one clock, and outputs a second high-frequency signal obtained by performing frequency conversion of a second over-sampling signal based on the second over-sampling signal delayed by one clock and the reference signal; a second filter unit that delays the second over-sampling signal by one clock, and outputs a third high-frequency signal obtained by performing frequency conversion of a third over-sampling signal based on the third over-sampling signal delayed by one clock and the reference signal; and an adder unit that adds the first high-frequency signal, the second high-frequency signal, and the third high-frequency signal, and outputs an output signal.