MODULATOR, SEMICONDUCTOR INTEGRATED CIRCUIT, AND WIRED AND WIRELESS COMMUNICATION DEVICE

摘要

PROBLEM TO BE SOLVED: To reduce a circuit size and a consumption current in transmission, and to acquire a highly precise modulation output, by directly modulating a VCO in response to transmission data.

SOLUTION: A transmission data signal is to be converted to an IQ modulated signal having a predetermined modulation width to be performed a phase modulation by a selection control signal inputted to a ROM 9 via a modulating circuit 10. The signal is to be converted to an appropriate signal level adjusted to control sensitivity of the VCO 5 after being converted to an analog signal by a DAC 8 and inputted to a gm variable unit 6 via a noise filter 7. A highly precise modulation output can be acquired after inputting the signal to a second input terminal for directly controlling a frequency of the VCO 5, modulating an oscillating frequency of the VCO 5, performing a band switching of the VCO 5 by inputting a control signal outputted from a BAND CTRL 13 to a third input terminal of the VCO 5 and a control terminal of the gm variable unit 6, while controlling transfer conductance of the gm variable unit 6 to make a modulation degree cased by an input signal from a second input terminal of the VCO 5 to be a target modulation degree in response to the control sensitivity of the VCO 5 varied in every BAND.

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