IC receiver to minimize tracking error

• US 20070004371A1
• Filed: 06/21/2006
• Published: 01/04/2007
• Est. Priority Date: 06/08/2001
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Okanobu, Taiwa
• Granted Patent: US 7,505,746 B2
• Time in Patent Office: Days
• US Class Current: 455/324
• CPC Class Codes: H04B 1/005 adapting radio receivers, transmitters andtransceivers for operation on two or more bands, i.e. frequency ranges
• CPC Class Codes: H04B 1/0057 using diplexing or multiplexing filters for selecting the desired band
• CPC Class Codes: H04B 1/0075 using different intermediate frequencied for the different bands
• CPC Class Codes: H04B 1/0082 with a common local oscillator for more than one band
• CPC Class Codes: H04B 1/28 the receiver comprising at least one semiconductor device having three or more electrodes
• CPC Class Codes: H04B 1/406 with more than one transmission mode, e.g. analog and digital modes

Abstract

A multi-band receiver in which characteristics including a tracking error are improved is provided with a variable frequency oscillator circuit, a variable divider circuit (39) for dividing an oscillation signal (SVCO) of the variable frequency oscillator circuit, and mixer circuits (15I) and (15Q) for subjecting a received signal SRX to frequency conversion into an intermediate frequency signal (SIF) by a local oscillation signal (SLO). A divided output of the variable divider circuit (39) is supplied as the local oscillation signal (SLO) to each of the mixer circuits (15I) and (15Q). When a signal in a first frequency band is received, the division ratio n of the variable divider circuit (39) and the oscillation frequency of the variable frequency oscillator are changed to change the reception frequency in the first frequency band. When a signal in a second frequency band is received, at least the oscillation frequency of the variable frequency oscillator circuit is changed to change the reception frequency in the second frequency band.

Claims

1. A receiver which is of a superheterodyne type which uses a plurality of frequency bands as reception bands, comprising:

a variable frequency oscillator circuit comprising a first variable divider circuit having a division ratio N that is changed to change an oscillation frequency of the variable frequency oscillator circuit;

a second variable divider circuit for dividing an oscillation signal supplied from the variable frequency oscillator circuit by a division ratio n to supply a local oscillation signal; and

a mixer circuit for subjecting a received signal to frequency conversion into an intermediate frequency signal by the local oscillation signal,

wherein the division ratio n of the second variable divider circuit and the division ratio N of the first variable divider circuit are changed to change the reception frequency.

2. A receiver according to claim 1, wherein a high-low ratio (ratio of the maximum frequency to the minimum frequency) in each of the plurality of frequency bands is set to approximately two.

3. A receiver according to claim 1, wherein the variable frequency oscillator circuit comprises a VCO forming a PLL, and the PLL comprises the first variable divider circuit.

4. A receiver which is of a superheterodyne type which uses at least a first frequency band and a second frequency band as reception bands, comprising:

a variable frequency oscillator circuit comprising a first variable divider circuit having a division ratio N that is changed to change an oscillation frequency of the variable frequency oscillator circuit;

a second variable divider circuit for dividing an oscillation signal of the variable frequency oscillator circuit which is supplied thereto to supply a local oscillation signal; and

a mixer circuit for subjecting a received signal to frequency conversion into an intermediate frequency signal by the local oscillation signal,

wherein, when a signal in the first frequency band is received, the division ratio n of the second variable divider circuit and the division ratio N of the first variable divider circuit are changed to change a reception frequency in the first frequency band, and

when a signal in the second frequency band is received, at least the division ratio N of the first variable divider circuit is changed to change a reception frequency in the second frequency band.

5. A receiver according to claim 4, wherein the variable frequency oscillator circuit comprises a VCO in a PLL, and the PLL comprises the first variable divider circuit.

6. A receiver according to claim 5, further comprising:

an antenna tuned circuit, which is electronically tuned, for selecting and obtaining a signal having a target frequency from the received signal and for supplying the selected signal to the mixer circuit,

wherein a control voltage supplied to the VCO is supplied as a tuning voltage to the antenna tuned circuit, and

when a signal in at least one of the first frequency band and the second frequency band is received, a tracking error is corrected for by changing the division ratio n and N.

7. A receiver according to claim 6, wherein a high-low ratio (ratio of the maximum frequency to the minimum frequency) in the first frequency band is substantially equal to a high-low ratio in the second frequency band.

8. A receiver according to claim 5, wherein a high-low ratio (ratio of the maximum frequency to the minimum frequency) of the oscillation frequency of the VCO is set to approximately two when signals in the first and second frequency bands are received.

9. A receiver according to claim 4, further comprising:

a variable low-pass filter provided before the mixer circuit,

wherein a cut-off frequency of the variable low-pass filter is changed according to the reception frequency so that an unwanted frequency component contained in the received signal is removed by the variable low-pass filter to eliminate a spurious interference wave caused by a harmonic signal of the local oscillation signal.

10. A receiver according to claim 5, further comprising:

a variable low-pass filter provided before the mixer circuit,

wherein a cut-off frequency of the variable low-pass filter is changed according to data for setting the division ratio N in the variable divider circuit of the PLL.

11. A receiver according to claim 4, wherein the local oscillation signal comprises a pair of local oscillation signals which are 90°

out of phase with each other,

the mixer circuit comprises a pair of mixer circuits to which the pair of local oscillation signals is supplied, and

output signals of the pair of mixer circuits are phase-shifted and computed to obtain the intermediate frequency signal.

12. (canceled)

13. An IC which forms a superheterodyne receiving circuit which uses at least a first frequency band and a second frequency band as reception bands, comprising:

a PLL;

a first variable divider circuit for dividing an oscillation signal of a VCO forming the PLL by a division ratio n to provide a local oscillation signal, wherein the division ratio n is changed, at least in part, based on a frequency band of the received signal; and

a mixer circuit for subjecting a received signal to frequency conversion into an intermediate frequency signal by the local oscillation signal,

the PLL, the variable divider circuit, and the mixer circuit being formed on one chip,

wherein, when a signal in the first frequency band is received, the division ratio n of the first variable divider circuit and a division ratio N of a second variable divider circuit forming the PLL are changed to change a reception frequency in the first frequency band, and

when a signal in the second frequency band is received, at least the division ratio N of the second variable divider circuit forming the PLL is changed to change a reception frequency in the second frequency band.

14. An IC which forms a superheterodyne receiving circuit which uses at least a first frequency band and a second frequency band as reception bands, comprising:

a high-frequency amplifier to which a received signal output from an antenna tuned circuit is supplied;

a filter circuit for selecting the received signal output from an output signal of the high-frequency amplifier;

a pair of mixer circuits for subjecting the received signal selected by the filter circuit to frequency conversion into a pair of intermediate frequency signals by a pair of local oscillation signals;

a processor circuit for phase-shifting and computing the pair of intermediate frequency signals to output a desired intermediate frequency signal component;

a PLL; and

a first variable divider circuit having a division ratio n for dividing an oscillation signal of a VCO forming the PLL into a pair of divided signals which have an equal frequency and which are 90°

out of phase with respect to each other, wherein the division ratio n is changed, at least in part, based on a frequency band of the received signal,

the high-frequency amplifier, the filter circuit, the pair of mixer circuits, the processor circuit, the PLL, and the first variable divider circuit being formed on one chip,

wherein a pair of divided signals is supplied as the pair of local oscillation signals to the pair of mixer circuits; and

when a signal in the first frequency band is received, the division ratio n of the first variable divider circuit and a division ratio of a second variable divider circuit forming the PLL are changed to change a reception frequency in the first frequency band, and

when a signal in the second frequency band is received, the division ratio of the second variable divider circuit forming the PLL is changed to change a reception frequency in the second frequency band.