Semiconductor integrated circuit device and frequency synthesizer
AssigneeKabushiki Kaisha Toshiba
InventorDaisuke MIYASHITA
Life of this patent
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Abstract
A semiconductor integrated circuit includes: a resonance circuit configured to determine an oscillation frequency; a first MOS transistor connected to the resonance circuit and configured to constitute an oscillation unit for delivering an oscillation output having the oscillation frequency; a second MOS transistor connected in parallel with the first MOS transistor; and a control unit configured to turn on and off the second MOS transistor according to the oscillation frequency, thereby enabling an equivalent gate width based on the first and second MOS transistors to be increased and decreased. Consequently, there is obtained an oscillation output having reduced phase noise, while an adequate oscillation margin is maintained.
Claims19
A semiconductor integrated circuit device comprising:
- a resonance circuit configured to determine an oscillation frequency;
- a first MOS transistor connected to the resonance circuit and configured to constitute an oscillation unit for delivering an oscillation output having the oscillation frequency;
- a second MOS transistor connected in parallel with the first MOS transistor;
- and
- a control unit configured to turn on and off the second MOS transistor according to the oscillation frequency, thereby enabling an equivalent gate width based on the first and second MOS transistors to be increased and decreased.
A frequency synthesizer comprising:
- a voltage-controlled oscillator composed of a resonance circuit having a resonance frequency based on the capacitance of a variable-capacitance unit capacitance of which varies according to information including an oscillation frequency and of an oscillation unit including oscillation transistors connected to the resonance circuit and configured to deliver an oscillation output having the resonance frequency;
- and
- a control unit configured to be provided with oscillation frequency information to be supplied to a PLL circuit configured to generate information including the oscillation frequency on the basis of the output of the voltage-controlled oscillator and the oscillation frequency information, so as to variable-control the gate widths of the oscillation transistors constituting the oscillation unit.
Dependencies are inferred from the claim text.