Patent ID: 7945219

Claim:
A transmission circuit for generating and outputting a transmission signal based on input data, the transmission circuit comprising: a signal generation section operable to generate an amplitude signal and a phase signal based on an amplitude component and a phase component which are obtained by performing signal processing on the input data; an amplitude amplifying section operable to output a signal which is controlled according to the amplitude signal; a frequency modulation circuit for frequency modulating and outputting an output frequency modulation signal, the frequency modulation circuit comprising: a bandpass type delta sigma modulation section operable to receive the phase signal, perform delta sigma modulation on the received phase signal, such that quantization noise is suppressed in a frequency band which requires low noise, and output a first resultant signal; a feedback comparison section operable to receive the same phase signal, compare the output frequency modulation signal with the received phase signal, control a frequency of the received phase signal according to a result of the comparison, and output a frequency-controlled phase signal; a loop filter operable to suppress a high-frequency component of the frequency-controlled phase signal and output a second resultant signal; and a voltage controlled oscillator operable to perform frequency-modulation by controlling an oscillatory frequency according to a combination of the second resultant signal outputted from the loop filter and the first resultant signal outputted from the bandpass type delta sigma modulation section, and output the output frequency modulation signal; and an amplitude modulation section operable to amplitude-modulate the output frequency modulation signal by using the signal outputted from the amplitude amplifying section, and output the amplitude-modulated frequency modulation signal as a transmission signal.