Frequency synthesizer and multi-band radio apparatus using said frequency synthesizer

• US 20020039894A1
• Filed: 08/17/2001
• Published: 04/04/2002
• Est. Priority Date: 08/17/2000
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Yoshida, Hiroshi, Umeda, Toshiyuki
• Granted Patent: US 6,985,701 B2
• Time in Patent Office: Days
• US Class Current: 455/265
• CPC Class Codes: H03B 21/02 by plural beating, i.e. for frequency synthesis ; Beating in combination with multiplication or division of frequency digital frequency synthesis using a ROM G06F1/02; digital frequency synthesis in general H03K; indirect frequency synthesis using a PLL H03L7/16
• CPC Class Codes: H04B 1/405 with multiple discrete channels

Abstract

There is disclosed a frequency synthesizer having an HF synthesizer for generating a first reference frequency signal having a variable frequency in a high-frequency band as a unit synthesizer, an LF synthesizer for generating a second reference frequency signal in a low-frequency band as another unit synthesizer, and an arithmetic circuit including a mixer for receiving the first and second reference frequency signals, a divider for receiving the second reference frequency signal, a mixer for receiving the first reference frequency signal and an output signal from the divider, a divider for receiving an output signal from the mixer, a divider for receiving an output signal from the mixer and capable of switching a division ratio, and a switch for switching and outputting output signals from the dividers, wherein an output signal of the switch is outputted as a first local signal, and an output signal from the divider is outputted as a second local signal.

Claims

1. A frequency synthesizer comprising:

a first synthesizer which outputs signal of which frequency is within one of a plurality of frequency bands;

a second synthesizer which outputs a fixed frequency signal;

a first mixer which mixes the signal output from the first synthesizer with the fixed frequency signal output from the second synthesizer;

a first divider which divides a signal output from the first mixer by a first division ratio;

a second divider which divides the fixed frequency signal output from the second synthesizer by a second division ratio;

a second mixer which mixes the signal output from the first synthesizer with a signal output from the second divider;

a third divider which divides a signal output from the second mixer by a third division ratio to output a signal to be used as a first local signal; and

a switch which outputs either a signal output from the first divider or a signal output from the third divider as a second local signal.

2. The frequency synthesizer of claim 1, wherein said first divider includes a first π

/2 phase shifter and said third divider includes a second π

/2 phase shifter, and wherein said switch outputs first and second phase signals having phases different from each other by π

/2.

3. The frequency synthesizer of claim 1, further comprising a first filter inserted between said first mixer and said first divider, and a second filter inserted between said second mixer and said third divider.

4. The frequency synthesizer of claim 1, further comprising a fourth divider which divides a signal output from said switch by a fourth division ratio.

5. The frequency synthesizer of claim 2, further comprising a fourth divider which divides a signal output from said switch by a fourth division ratio, and a fifth divider which divides a signal output from said switch by a fifth division ratio.

6. The frequency synthesizer of claim 2, further comprising a sixth divider inserted between said third divider and said switch.

7. A frequency synthesizer comprising:

a first synthesizer which outputs a signal of which frequency is within one of a plurality of frequency bands;

a second synthesizer which outputs a fixed frequency signal;

a first divider which divides the fixed frequency signal output from the second synthesizer by a first division ratio;

a mixer which mixes the signal output from the first synthesizer with a signal output from the first divider;

a second divider which divides a signal output from the mixer by a second division ratio to output a first local signal;

a third divider which divides the fixed frequency signal output from the second synthesizer by a third division ratio to output a second local signal; and

a fourth divider which divides the signal output from the first synthesizer by a fourth division ratio to output a third local signal.

8. The frequency synthesizer according to claim 7, further comprising a first filter inserted between said first divider and said mixer, and a second filter inserted between said mixer and said second divider.

10. The frequency synthesizer of claim 7, further comprising:

a second mixer which mixes a signal output from said fourth divider with a signal output from said third divider; and

a switch which outputs either a signal output from the second mixer or a signal output from the third divider as a second local signal.

9. A frequency synthesizer comprising:

a first synthesizer which outputs a signal of which frequency is within one of a plurality of frequency bands;

a second synthesizer which outputs first fixed frequency signal;

a third synthesizer which outputs second fixed frequency signal;

a first mixer which mixes the signal output from the first synthesizer with the second fixed frequency signal output from the third synthesizer;

a first divider which divides a signal output from the first mixer by a first division ratio to output a first local signal;

a second divider which divides the first fixed frequency signal output from the second synthesizer by a second division ratio to output a second local signal; and

a third divider which divides the signal output from the first synthesizer by a third division ratio to output a third local signal.

11. A multi-band radio apparatus comprising:

a frequency synthesizer including;

a first synthesizer which outputs signal of which frequency is within one of a plurality of frequency bands;

a second synthesizer which outputs a fixed frequency signal;

a first mixer which mixes the signal output from the first synthesizer with the fixed frequency signal output from the second synthesizer;

a first divider which divides a signal output from the first mixer by a first division ratio;

a second divider which divides the fixed frequency signal output from the second synthesizer by a second division ratio;

a second mixer which mixes the signal output from the first synthesizer with a signal output from the second divider;

a third divider which divides a signal output from the second mixer by a third division ratio to output a signal to be used as a first local signal; and

a switch which outputs either a signal output from the first divider or a signal output from the third divider as a second local signal;

a quadrature demodulator connected to the frequency synthesizer, which demodulates a received signal by use of said reception local signal; and

a quadrature modulator connected to the frequency synthesizer, which modulates a signal to be transmitted by use of said transmission local signal.

12. A multi-band radio apparatus comprising:

a frequency synthesizer including;

a first synthesizer which outputs a signal of which frequency is within one of a plurality of frequency bands;

a second synthesizer which outputs a fixed frequency signal;

a first divider which divides the fixed frequency signal output from the second synthesizer by a first division ratio;

a mixer which mixes the signal output from the first synthesizer with a signal output from the first divider;

a second divider which divides a signal output from the mixer by a second division ratio to output a first local signal;

a third divider which divides the fixed frequency signal output from the second synthesizer by a third division ratio to output a second local signal; and

a fourth divider which divides the signal output from the first synthesizer by a fourth division ratio to output a third local signal.

a quadrature demodulator connected to the frequency synthesizer, which demodulates a received signal by use of said reception local signal;

a quadrature modulator connected to the frequency synthesizer, which modulates a signal to be transmitted by use of said first transmission local signal; and

a frequency converter connected to the quadrature modulator and the frequency synthesizer, which converts a frequency of a signal output from the quadrature modulator by use of said second transmission local signal.

13. A frequency synthesizer comprising:

a first signal generator which outputs a first signal of which frequency is within one of a plurality of frequency bands;

a second signal generator which outputs a second signal having a fixed frequency;

a first mixer which mixes the first and second signals and outputs a first mixed signal;

a first divider which divides the first mixed signal by a first division ratio and outputs a first divided signal;

a second divider which divides the second signal by a second division ratio and outputs a second divided signal;

a second mixer which mixes the first signal and the second divided signal and outputs a second mixed signal;

a third divider which divides the second mixed signal by a third division ratio to output a first local signal; and

a switch which selects either the first divided signal or the first local signal and outputs a second local signal.

14. A frequency synthesizer comprising:

a first signal generator which outputs a first signal of which frequency is within one of a plurality of frequency bands;

a second signal generator which outputs a second signal having a fixed frequency;

a first divider which divides the second signal by a first division ratio and outputs a first divided signal;

a mixer which mixes the first signal with the first divided signal and outputs a mixed signal;

a second divider which divides the mixed signal by a second division ratio to output a first local signal;

a third divider which divides the second signal by a third division ratio to output a second local signal; and

a fourth divider which divides the first signal by a fourth division ratio to output a third local signal.

15. A frequency synthesizer comprising:

a first signal generator which outputs a first signal of which frequency is within one of a plurality of frequency bands;

a second signal generator which outputs a second signal having a first fixed frequency;

a third signal generator which outputs a third signal having a second fixed frequency;

a mixer which mixes the first signal with the third signal to output a mixed signal;

a first divider which divides the mixed signal by a first division ratio to output a first local signal;

a second divider which divides the second signal by a second division ratio to output a second local signal; and

a third divider which divides the first signal by a third division ratio to output a third local signal.