US 8,619,997 B2Granted

Receiving apparatus

AssigneesSanyo Semiconductor Co., Ltd., Semiconductor Components Industries, LLC

InventorsKazunari Kurokawa, Satoru Sekiguchi

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Abstract

A receiving apparatus includes: a local oscillator to output first- and second-local-oscillator signals whose phases are orthogonal to each other; a mixer to output first- and second-intermediate-frequency signals; a first filter to allow a component from a desired signal to pass therethrough, and eliminate a component from an image signal having a frequency symmetrical with that of the desired signal, in the first- and second-intermediate-frequency signals; a second filter to allow a component from the image signal to pass therethrough, and eliminate a component from the desired signal, in the first- and second-intermediate-frequency signals; a comparator to compare levels between output signals of the first and second filters; and a control unit to switch a frequency of the first- and second-local-oscillator signals to a difference frequency between a frequency of the desired signal and the intermediate frequency or a sum frequency thereof, according to a comparison result of the comparator.

Claims16

Dependent claims

A receiving apparatus comprising:

a local oscillator configured to output first and second local oscillator signals whose phases are orthogonal to each other;
a mixer configured to mix a received signal with the first local oscillator signal and output a first intermediate frequency signal, and to mix a received signal with the second local oscillator signal and output a second intermediate frequency signal, the first and second intermediate frequency signals having a predetermined intermediate frequency;
a first filter configured to allow a component from a desired signal to be received to pass therethrough, and eliminate a component from an image signal having a frequency symmetrical with a frequency of the desired signal with respect to a frequency of the first and second local oscillator signals, in the first and second intermediate frequency signals;
a second filter configured to allow a component from the image signal to pass therethrough, and eliminate a component from the desired signal, in the first and second intermediate frequency signals;
a comparator configured to compare levels between output signals of the first and second filters;
and
a control unit configured to switch the frequency of the first and second local oscillator signals to a difference frequency between the frequency of the desired signal and the intermediate frequency or to a sum frequency of the frequency of the desired signal and the intermediate frequency, according to a comparison result of the comparator.

4 more elements

A receiving apparatus comprising:

a local oscillator configured to output first and second local oscillator signals whose phases are orthogonal to each other;
a mixer configured to mix a received signal with the first local oscillator signal and output a first intermediate frequency signal, and to mix a received signal with the second local oscillator signal and output a second intermediate frequency signal, the first and second intermediate frequency signals having a predetermined intermediate frequency;
a first filter configured to allow a component from a desired signal to be received to pass therethrough, and eliminate a component from an image signal having a frequency symmetrical with a frequency of the desired signal with respect to a frequency of the first and second local oscillator signals, in the first and second intermediate frequency signals;
a second filter configured to allow a component from the image signal to pass therethrough, and eliminate a component from the desired signal, in the first and second intermediate frequency signals;
a first adder configured to add a first in-phase signal and a first quadrature signal that contain a component of the desired signal allowed to pass through the first filter;
a second adder configured to add a second in-phase signal and a second quadrature signal that contain a component of the image signal allowed to pass through the second filter;
a comparator configured to compare levels between output signals of the first and second adders;
and
a control unit configured to switch the frequency of the first and second local oscillator signals to a difference frequency between the frequency of the desired signal and the intermediate frequency or to a sum frequency of the frequency of the desired signal and the intermediate frequency, according to a comparison result of the comparator.

6 more elements

Dependencies are inferred from the claim text.