# US 2014/0152394 A1 · Frequency detection circuits, radio frequency signal processing devices and methods for calibrating inductance and capacitance > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0152394 A1 - Document ID: US20140152394A1 - Status: Published application - Kind: A1 - Application number: 14/017,391 - Filed: 2013-09-04 - Published: 2014-06-05 - Earliest claimed: 2012-12-04 - Assignees: VIA Telecom Co., Ltd. - Applicants: VIA Telecom, Inc. - Inventors: Hsien-Ku CHEN; Bing-Jye KUO; Fang-Ren LIAO; Pei-Wei CHEN - Web page: https://patentgrep.com/patent/US20140152394A1 ## CPC - G01R 35/005: {Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references (G01R33/0035, G01R35/002 take precedence)} - G01R 35/00: Testing or calibrating of apparatus covered by the other groups of this subclass - G01R 31/2822: {of microwave or radiofrequency circuits (of attenuation, gain, e.g. using network analyzers G01R27/28)} - G01R 31/64: Testing of capacitors - G01R 31/72: Testing of electric windings (testing of transformers G01R31/62) - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract A frequency detection circuit includes a filter, a power detector and a voltage comparator. The filter receives and filters a converted signal to generate a filtered signal. The power of the filtered signal relates to a frequency of the converted signal. The power detector generates a voltage according to the power of the filtered signal. The voltage comparator compares the voltage with multiple reference voltages to generate multiple comparison results. At least one of the inductance and capacitance of an LC tank in an amplifier is adjusted according to the comparison results. ## Claims ### Claim 1 A frequency detection circuit, comprising: a filter, receiving and filtering a converted signal 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. ### Claim 2 (depends on 1) The frequency detection circuit as claimed in claim 1, wherein the filter is an image rejection filter. ### Claim 3 (depends on 1) The frequency detection circuit as claimed in claim 1, wherein the converted signal is generated by frequency down-converting an oscillating signal oscillating at an oscillating frequency according to a desired frequency, and the LC tank is utilized to generate the oscillating signal. ### Claim 4 (depends on 1) The frequency detection circuit as claimed in claim 1, wherein the voltage comparator comprises a plurality of comparators for comparing the voltage with one of the reference voltages to generate the comparison results. ### Claim 5 A radio frequency signal processing device, comprising: a low-noise amplifier, comprising: an LC tank; an amplifier circuit, coupled to the LC tank at a pair of differential output terminals; a cross-coupled transistor pair, couple to the LC tank at the pair of differential output terminals; and a current source, coupled to the cross-coupled transistor pair, wherein the cross-coupled transistor pair, the LC tank and the current source form a self-oscillation circuit for generating an oscillating signal oscillating at an oscillating frequency according to an inductance and a capacitance of the LC tank; a mixer, down-converting the oscillating signal according to a desired frequency to generate a converted signal; and a frequency detection circuit, coupled to the low-noise amplifier and the mixer for detecting a frequency of the converted signal and generating a calibration signal according to the frequency, wherein at least one of the inductance and the capacitance of the LC tank is adjusted according to the calibration signal. ### Claim 6 (depends on 5) The radio frequency signal processing device as claimed in claim 5, wherein the frequency detection circuit comprises: a filter, receiving and filtering the converted signal to generate a filtered signal, wherein a power of the filtered signal relates to the 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 the calibration signal. ### Claim 7 (depends on 5) The radio frequency signal processing device as claimed in claim 5, wherein the filter is an image rejection filter. ### Claim 8 (depends on 6) The radio frequency signal processing device as claimed in claim 6, wherein the voltage comparator comprises a plurality of comparators for respectively comparing the voltage with one of the reference voltages to generate a plurality of comparison results and generate the calibration signal according to the comparison results. ### Claim 9 (depends on 5) The radio frequency signal processing device as claimed in claim 5, wherein the low-noise amplifier operates in at least a calibration mode and a receiving mode, and in the calibration mode, the amplifier circuit is disabled and the current source is enabled such that the cross-coupled transistor pair, the LC tank and the current source form the self-oscillation circuit for generating the oscillating signal. ### Claim 10 (depends on 9) The radio frequency signal processing device as claimed in claim 9, wherein in the receiving mode, the current source is disabled and the amplifier circuit is enabled such that the amplifier circuit and the LC tank form a low-noise amplifier circuit for amplifying a received radio frequency signal. ### Claim 11 A method for calibrating inductance and capacitance, comprising: generating an oscillating signal oscillating at an oscillating frequency via an LC tank; frequency down-converting the oscillating signal according to a desired frequency to generate a converted signal; 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; generating a calibration signal according to the power; and adjusting at least one of an inductance and a capacitance of the LC tank according to the calibration signal. ### Claim 12 (depends on 11) The method as claimed in claim 11, wherein the LC tank is comprised in a low-noise amplifier. ### Claim 13 (depends on 12) The method as claimed in claim 12, wherein the step of generating the oscillating signal oscillating at the oscillating frequency via the LC tank is performed by a self-oscillation circuit comprised in the low-noise amplifier. ### Claim 14 (depends on 11) The method as claimed in claim 11, wherein the step of filtering the converted signal according to the predetermined frequency response is performed by an image rejection filter. ### Claim 15 (depends on 11) The method as claimed in claim 11, wherein the step of generating the calibration signal according to the power further comprises: generating a voltage according to the power; comparing the voltage with a plurality of reference voltages to generate a plurality of comparison results; and generating the calibration signal according to the comparison results.