US 6,334,051 B1Granted

Direct conversion receiver with wide band analog frequency conversion front end and digital demodulating and selecting back end

AssigneeKabushiki Kaisha Toshiba

InventorsHiroshi Tsurumi, Hiroshi Yoshida

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Abstract

A radio-frequency signal receive section, including an antenna, collectively receives radio-frequency signals on a plurality of channels each of which is modulated with data and outputs a received signal. In a quadrature demodulator, the received signal is multiplied by each of first quadrature local signals to produce quadrature baseband signals. In two low-pass filters, low-frequency component signals are extracted from the quadrature baseband signals. In a quadrature modulator, the low-frequency component signals are multiplied by second quadrature local signals and thereby converted into quadrature intermediate-frequency signals, which are in turn combined into an output signal. After converted into a digital signal, the output signal of the quadrature modulator is inputted to a digital signal processing unit where a signal on at least one channel is selected and the selected signal is processed to recover the original data.

Claims10

Dependent claims

A receiver adaptable to a plurality of radio communication systems comprising:

a radio-frequency signal reception unit which collectively receives radio-frequency signals on a plurality of channels each of which is modulated with data;
a quadrature demodulator which multiplies each of the radio-frequency signals by a first local signal to produce a first baseband signal, and multiplies each of the radio-frequency signals by a second local signal having a π/2-phase differs from the first local signal to produce a second baseband signal having a π/2-phase differs from the first baseband signal;
a first low-pass filter which outputs a first low-frequency component signal from the first baseband signal;
a second low-pass filter which outputs a second low-frequency component signal from the second baseband signal;
a quadrature modulator which multiplies the first low-frequency component signal by a third local signal to produce a first intermediate-frequency signal, multiplies the second low-frequency component signal by a fourth local signal having a π/2-phase differs from the third local signal to produce a second intermediate-frequency signal, and combines the first intermediate-frequency signal and the second intermediate-frequency signal into an output signal;
an A/D converter which converts the outputs signal into a digital signal;
a digital downconverter which multiplies the digital signal by a first clock signal to produce a first digital baseband signal, multiplies the digital signal by a second clock signal having a π/2-phase differs from the first clock signal to produce a second digital baseband signal having a π/2-phase differs from the first baseband signal and selects a signal on at least one channel from the first digital baseband signal, selects a signal on at least one channel from the second digital baseband signal;
a digital signal processing unit which processes the first digital baseband signal and second digital baseband signal to recover the data.

5 more elements

A receiver adaptable to a plurality of radio communication systems, comprising:

a radio-frequency signal reception unit that collectively receives radio-frequency signals on a plurality of channels, each radio-frequency signal being modulated with data;
a quadrature demodulator unit that multiplies each of the radio-frequency signals by a first local signal to produce a first baseband signal, and multiplies each of the radio-frequency signals by a second local signal, having a π/2-phase difference from the first local signal, to produce a second baseband signal, having a π/2-phase difference from the first baseband signal;
a first low-pass filter unit that outputs a first low-frequency component signal from the first baseband signal;
a second low-pass filter unit that outputs a second low-frequency component signal from the second baseband signal;
at least one A/D converter unit that converts the first low-frequency component signal and the second low-frequency component signal into a digital signal;
and
a digital signal processing unit that selects a signal based on a desired one of the channels from the digital signal, and processes the signal to recover the data, wherein the digital signal processing unit includes,
a quadrature modulator unit that multiplies the first low-frequency component signal by a third local signal to produce a first intermediate-frequency signal, multiplies the second low-frequency component signal by a fourth local signal, having a π/2-phase difference from the third local signal, to produce a second intermediate-frequency signal, and combines the first intermediate-frequency signal and the second intermediate-frequency signal into an output signal,
a digital downconverter unit that multiplies the output signal by a first clock signal to produce a first digital baseband signal, multiplies the output signal by a second clock signal, having a π/2-phase difference from the first clock signal, to produce a second digital baseband signal, having π/2-phase difference from the first baseband signal, and selects a signal on at least one channel from the first digital baseband signal and selects a signal on at least one channel from the second digital baseband signal, and
a digital signal processor unit that processes the first digital baseband signal and second digital baseband signal to recover the data.

7 more elements

A receiver adaptable to a plurality of radio communication systems, comprising:

a radio-frequency signal reception unit that collectively receives radio-frequency signals on a plurality of channels, each radio-frequency signal being modulated with data;
a quadrature demodulator unit that multiplies each of the radio-frequency signals by a first local signal to produce a first baseband signal, and multiplies each of the radio-frequency signals by a second local signal, having a π/2-phase difference from the first local signal, to produce a second baseband signal, having a π/2-phase difference from the first baseband signal;
a first low-pass filter unit that outputs a first low-frequency component signal from the first baseband signal;
a second low-pass filter unit that outputs a second low-frequency component signal from the second baseband signal;
at least one A/D converter unit that converts the first low-frequency component signal and the second low-frequency component signal into a digital signal;
and
a digital signal processing unit that selects a signal based on a desired one of the channels from the digital signal, and processes the signal to recover the data, wherein the digital signal processing unit includes,
a digital downconverter unit that multiplies the first low-frequency component signal and the second low-frequency component signal from the A/D converter unit by a common clock signal to produce a first digital baseband signal and a second digital baseband signal, having a π/2-phase difference from the first baseband signal, and selects a signal on at least one channel from the first digital baseband signal and selects a signal on at least one channel from the second digital baseband signal, and
a digital signal processor unit that processes the first digital baseband signal and second digital baseband signal to recover the data.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/262,104Filed 4 Mar 1999
Priority: JP 10-0521684 Mar 1998
Granted: 25 Dec 2001
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

H04B 1/0007
Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or…
H03D 7/166
At least two frequency changers being located in different paths, e.g. in two paths with carriers in quadrature: using two or more quadrature…
H04B 1/28
For superheterodyne receivers: the receiver comprising at least one semiconductor device having three or more electrodes
H04B 1/30
Circuits: for homodyne or synchrodyne receivers