Patent ID: 8466717
Filing Date: 2013-06-18
Classification: H03L

Abstract:
1. A frequency synthesizer, comprising: a divide unit for dividing a frequency signal output from a voltage controlled oscillating unit depending on a control voltage to achieve a frequency divided signal; an analog/digital converting unit for digitizing the frequency-divided frequency signal; a vector extracting unit that quadrature-detects an output signal from the analog/digital converting unit using a digital sinusoidal detecting signal to extract a real part and an imaginary part of a complex expression of a rotation vector rotating at a frequency corresponding to a frequency difference between the output signal from the analog/digital converting unit and the digital sinusoidal detecting signal; a frequency difference extracting unit for extracting a frequency difference between a first frequency of the rotation vector when the frequency of the frequency signal output from the voltage controlled oscillating unit becomes a set frequency and a second frequency of the rotation vector as extracted in the vector extracting unit; an integrating unit for integrating values corresponding to a frequency difference extracted by the frequency difference extracting unit; a digital/analog converting unit for converting output from the integrating unit to an analog signal to supply an integration result as the control voltage to the voltage controlled oscillating unit; a monitoring unit that monitors the control voltage to be input to the voltage controlled oscillating unit; and an output unit for determining whether a level of the control voltage monitored by said monitoring unit deviates from a set range determined in advance and outputting an unlock detection signal when the level deviates from the set range, wherein the vector extracting unit comprises: