Abstract: A circuit with variation correction function is capable of obtaining an output characteristic near a desired value by suppressing variation of the output characteristic regardless of manufacturing characteristic variations of a component. An output signal different in phase from a reference signal is obtained by a dummy circuit having a capacitor of a same structure as a correction object capacitor in an operation circuit. The difference in phase between the reference signal and the output signal reflects manufacturing characteristic variation of the correction object capacitor. The difference in phase is detected by a phase comparator circuit and control signals are created by a control signal conversion circuit. Switches in the operation circuit are changed over with the control signal to adjust the capacitance of the correction object capacitor.

Abstract: A voltage control oscillation (VCO) circuit and an adjusting method for the same, which enables an adjustment for suppressing the dispersion of the output characteristic in spite of the manufacture-related dispersion of element characteristics, using a simple circuit configuration, are provided. A low-pass filter 15 and a high-pass filter 16 are composed of the elements that have the same structure as elements composing the VCO circuit 11, and a prescribed correlation is established between both elements. A corrective element 14 is connected in parallel to a main element, in which an oscillation frequency control signal VT is input, in the VCO circuit 11. Respective frequency-gain characteristic lines of the low-pass/high-pass filters 15 and 16 have gradients reverse to each other and cross at a target gain TG. When the capacitance value lowers in dispersion, the level of an output signal SL2 becomes higher than that of an output signal SH2 at a reference frequency fREF to form an output level difference LD2.

Abstract: A voltage control oscillation (VCO) circuit and an adjusting method for the same, which enables an adjustment for suppressing the dispersion of the output characteristic in spite of the manufacture-related dispersion of element characteristics, using a simple circuit configuration, are provided. A low-pass filter 15 and a high-pass filter 16 are composed of the elements that have the same structure as elements composing the VCO circuit 11, and a prescribed correlation is established between both elements. A corrective element 14 is connected in parallel to a main element, in which an oscillation frequency control signal VT is input, in the VCO circuit 11. Respective frequency-gain characteristic lines of the low-pass/high-pass filters 15 and 16 have gradients reverse to each other and cross at a target gain TG. When the capacitance value lowers in dispersion, the level of an output signal SL2 becomes higher than that of an output signal SH2 at a reference frequency fREF to form an output level difference LD2.

Abstract: A voltage controlled oscillator having a wide oscillation frequency band, desirable carrier-noise characteristic, and desirable linearity of the oscillation frequency relative to a control voltage. The voltage controlled oscillator includes an oscillation unit and a control unit. The oscillation unit generates an output signal having an oscillation frequency corresponding to the control voltage in one of a plurality of oscillation frequency bands. The oscillation unit includes a switching unit for selecting one of the plurality of oscillation frequency bands in accordance with a switching signal. The control unit generates the switching signal in accordance with the control voltage.

Abstract: A voltage controlled oscillator having a wide oscillation frequency band, desirable carrier-noise characteristic, and desirable linearity of the oscillation frequency relative to a control voltage. The voltage controlled oscillator includes an oscillation unit and a control unit. The oscillation unit generates an output signal having an oscillation frequency corresponding to the control voltage in one of a plurality of oscillation frequency bands. The oscillation unit includes a switching unit for selecting one of the plurality of oscillation frequency bands in accordance with a switching signal. The control unit generates the switching signal in accordance with the control voltage.

Abstract: This invention provides a circuit with variation correction function capable of obtaining an output of the characteristic near a desired value by suppressing variation of the output characteristic regardless of the manufacturing characteristic variation of a component. An output signal fref′ different from the reference signal fref in terms of phase is obtained by the dummy circuit 3 having a capacitor of the same structure as a correction object capacitor in a VCO circuit 11, which is an actual operation circuit. A difference in phase between the reference signal fref and the output signal fref′ reflects manufacturing characteristic variation of the correction object capacitor. The difference in phase is detected by a phase comparator circuit 14 and control signals vsw1-vsw4 are created by a control signal conversion circuit 15 corresponding to its output signal vpd.

Abstract: A reference frequency divider divides a clock signal into a reference frequency signal, and outputs it. A comparison frequency divider circuit divides an output signal from a voltage controlled oscillator, and outputs it as a comparison signal. The reference signal and comparison signal are coupled to a phase comparator. The phase comparator detects the phase difference between the reference signal and comparison signal, and outputs a phase difference signal. A charge pump outputs a voltage signal in response to the phase difference signal from the phase comparator. A low pass filter smooths out the voltage signal from the charge pump to remove the high frequency components, and outputs a controlled voltage signal. A voltage controlled oscillator outputs an output signal with the frequency relating to the voltage value of the controlled voltage signal from the low pass filter. A frequency difference determining circuit compares the reference signal with the comparison signal.