Patent ID: 9274200
Filing Date: 2016-03-01
CPC Classification: G01R

Claim Text:
1. A frequency detection circuit, comprising: a filter, receiving a converted signal and filtering the converted signal according to a predetermined frequency response to generate a filtered signal, wherein a power of the filtered signal relates to a frequency of the converted signal; a power detector, coupled to the filter for generating a voltage according to the power of the filtered signal; and a voltage comparator, comparing the voltage with a plurality of reference voltages to generate a plurality of comparison results, wherein at least one of an inductance and a capacitance of an LC tank in an amplifier is adjusted according to the comparison results in a calibration mode, wherein the amplifier operates in at least the calibration mode and a receiving mode, and in the calibration mode, an amplifier circuit of the amplifier is disabled and a current source of the amplifier is enabled such that a cross-coupled transistor pair of the amplifier, the LC tank and the current source form a self-oscillation circuit for generating an oscillating signal.