Patent ID: 9154143
Filing Date: 2015-10-06
Classification: H03L,H04L

Abstract:
1. A semiconductor device comprising: a controlled oscillator including: a control unit controlling the capacitance value of said first capacitive unit and said current adjustment unit; a frequency divider outputting a frequency-divided signal of said local oscillation signal; a phase comparator outputting a signal corresponding to a phase difference between an output of said frequency divider and a given reference signal; a filter unit generating a feedback signal by removing a high-frequency component of an output of said phase comparator; a modulator modulating said local oscillation signal using a given baseband signal and outputting said modulated local oscillation signal; and an amplifier having an adjustable gain amplifying an output of said modulator, wherein: said resonance circuit further includes a second capacitive unit having a capacitance value varying in accordance with a value of said feedback signal, when said control unit instructs said current adjustment unit to change the value of the drive current to be supplied to said amplification unit, said control unit changes the capacitance value of said first capacitive unit to keep said oscillation frequency constant, and said control unit instructs said current adjustment unit to change the value of the drive current to be supplied to said amplification unit in accordance with the gain of said amplifier.