Semiconductor device, radio communication terminal, and method for controlling semiconductor device

Abstract

A semiconductor device according to the present invention includes a PLL circuit, in which the PLL circuit includes: a phase difference detection unit that detects a phase difference between a reference signal and a division signal; a filter that outputs a control signal according to a detection result of the phase difference detection unit; an oscillation unit that outputs an oscillation signal of a frequency according to the control signal; a division unit that divides the oscillation signal to output it as the division signal; a noise intensity detection unit that detects a noise intensity of a predetermined frequency component included in the control signal; and a phase difference adjustment unit that adjusts a phase difference between the reference signal and the division signal based on the noise intensity detected by the noise intensity detection unit.

1 - 12 . (canceled) 
     
     
         13 . A radio communication terminal comprising:
 an antenna that wirelessly transmits/receives a high-frequency signal;   a PLL circuit that generates an oscillation signal;   a mixer that demodulates the high-frequency signal to a baseband signal by using the oscillation signal, or modulates a baseband signal to the high-frequency signal by using the oscillation signal; and   a baseband signal processing unit that performs a predetermined process based on the baseband signal demodulated by the mixer, or generates the baseband signal to be modulated by the mixer according to a result of the predetermined process,   wherein the PLL circuit includes:   (a) a phase difference detection unit that detects a phase difference between a reference signal and a division signal;   (b) a filter that outputs a control signal according to a detection result of the phase difference detection unit;   (c) an oscillation unit that outputs the oscillation signal of a frequency according to the control signal;   (d) a division unit that divides the oscillation signal to output it as the division signal;   (e) a noise intensity detection unit that detects a noise intensity of a predetermined frequency component included in the control signal; and   (f) a phase difference adjustment unit that adjusts a phase difference between the reference signal and the division signal based on the noise intensity detected by the noise intensity detection unit.   
     
     
         14 . The radio communication terminal according to  claim 13 , wherein the noise intensity detection unit detects the noise intensity by performing Fourier transform of the predetermined frequency component included in the control signal. 
     
     
         15 . The radio communication terminal according to  claim 13 , wherein the phase difference adjustment unit adjusts the phase difference between the reference signal and the division signal using a span of adjustable range corresponding to the noise intensity indicating a minimum value among the plurality of noise intensities detected in a case where the phase difference has been adjusted using a plurality of different spans of adjustable range, respectively. 
     
     
         16 . The radio communication terminal according to  claim 13 , wherein the phase difference adjustment unit adjusts the phase difference between the reference signal and the division signal so that the noise intensity detected by the noise intensity detection unit after phase difference adjustment indicates the minimum value. 
     
     
         17 . The radio communication terminal according to  claim 13 , wherein
 the filter is a digital low-pass filter that outputs a digital code according to the detection result of the phase difference detection unit as the control signal, and   the oscillation unit is a digital control oscillator that outputs the oscillation signal of a frequency according to the digital code as the control signal.   
     
     
         18 . The radio communication terminal according to  claim 13 , wherein
 the PLL circuit further comprises an AD converter,   the filter is a low-pass filter that outputs the control signal of a voltage value according to the detection result of the phase difference detection unit,   the oscillation unit is a voltage control oscillator that outputs the oscillation signal of a frequency according to the voltage value of the control signal,   the AD converter converts the voltage value of the control signal into a digital signal, and   the noise intensity detection unit detects a noise intensity of a predetermined frequency component included in the digital signal.