Radio circuit having a local oscillator frequency which differs from the transmit frequency or the receive frequency and mobile radio apparatus

• US 6,421,530 B1
• Filed: 09/19/1997
• Issued: 07/16/2002
• Est. Priority Date: 09/20/1996
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Ikeda, Kazuhiko, Yasuno, Junichi, Adachi, Hisashi, Ishida, Kaoru, Haruki, Hiroshi, Kosugi, Hiroaki
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): SOBUTKA, PHILIP
• Application Number:
  US08/933,848
• Time in Patent Office: 1,761 Days
• Field of Search: 455/575, 455/76, 455/343, 455/75, 455/86, 455/550, 455/260, 455/265, 455/113, 455/118, 332/128, 332/117, 332/119, 332/126, 332/127, 331/2, 331/23, 331/25, 331/1.A, 329/325, 329/323, 375/324, 375/306, 375/307
• US Class Current: 455/86
• CPC Class Codes: H04B 1/403 using the same oscillator for generating both the transmitter frequency and the receiver local oscillator frequency

Abstract

The present invention concerns a radio circuit including a local oscillator, a first receive frequency converter, a frequency divider and a demodulator. A receive signal and an output of the local oscillator are input to the first receive frequency converter. The receive signal is converted into a first intermediate signal by the first receive frequency converter, and the first intermediate frequency signal is input to the demodulator. The output of the local oscillator is frequency-divided by the frequency divider and also input to the demodulator. The signal converted into the first intermediate frequency is demodulated into a baseband signal by the demodulator.

Claims

1. A radio circuit comprising a local oscillator at a local oscillator frequency, a first receive frequency converter, a second receive frequency converter, a frequency divider and a demodulator,

wherein a receive signal and an output of the local oscillator are input to the first receive frequency converter, the receive signal is converted into a signal of a first intermediate frequency by the first receive frequency converter, the signal of the first intermediate frequency is input to the second receive frequency converter, the output of the local oscillator at the local oscillator frequency is frequency-divided by the frequency divider and input to the second receive frequency converter, the signal of the first intermediate frequency is frequency-converted into a signal of a second intermediate frequency by the second receive frequency converter, the signal converted into the second intermediate frequency and a reference signal of the local oscillator are input to the demodulator, the signal of the second intermediate frequency is demodulated into a baseband signal by the demodulator, and the frequency of the reference signal equals the second intermediate frequency.

2. A mobile radio apparatus comprising a radio circuit according to claim 1, a signal processing circuit for processing the modulating signal or the baseband signal, and an antenna for handling the receive signal or the transmit signal.

3. A radio circuit according to claim 1, further comprising a transmit frequency converter and a modulator, wherein the output of the local oscillator is input to the transmit frequency converter, an output of the frequency divider is input to the modulator to be modulated into a transmit intermediate frequency signal with a modulating signal, and the transmit intermediate frequency signal is input to the transmit frequency converter to be frequency-converted into a signal of a transmit frequency.

4. A radio circuit according to claim 3, wherein a frequency division number of the frequency divider is an integer N, a receive frequency or the transmit frequency is lower than an output frequency of the local oscillator, the local oscillator is a phase-locked loop frequency synthesizer circuit, and a phase comparison frequency is f×

N/(N−

1) or {f×

N/(N−

1)}/m, wherein f is the transmit and receive frequency channel spacing and m is an integer including 1.

5. A radio circuit according to claim 3, wherein a frequency division number of the frequency divider is an integer N, a receive frequency or the transmit frequency is higher than an output frequency of the local oscillator, the local oscillator is a phase-locked loop frequency synthesizer circuit, and a phase comparison frequency is f×

N/(N+1) or {f×

N/(N+1)}/m, wherein f is the transmit and receive frequency channel spacing and m is an integer including 1.

6. A radio circuit according to claim 1, further comprising a modulator and a local frequency converter, wherein the output of the local oscillator is input to the frequency divider to be frequency-divided, the local frequency converter receives the output of the local oscillator and an output of the frequency divider to output a signal of a transmit frequency, and the modulator modulates an output of the local frequency converter with a modulating signal to output a signal of the transmit frequency.

7. A radio circuit according to claim 6, wherein a frequency division number of the frequency divider is an integer N, a receive frequency or the transmit frequency is higher than an output frequency of the local oscillator, the local oscillator is a phase-locked loop frequency synthesizer circuit, and a phase comparison frequency is f×

N/(N+1) or {f×

N/(N+1)}/m, wherein f is the transmit and receive frequency channel spacing and m is an integer including 1.

8. A radio circuit according to claim 6, wherein a frequency division number of the frequency divider is an integer N, a receive frequency or the transmit frequency is lower than an output frequency of the local oscillator, the local oscillator is a phase-locked loop frequency synthesizer circuit, and a phase comparison frequency is f×

N/(N−

1) or {f×

N/(N−

1)}/m, wherein f is the transmit and receive frequency channel spacing and m is an integer including 1.

9. A radio circuit comprising a local oscillator at a local oscillator frequency, a first receive frequency converter, a frequency divider and a demodulator, wherein

a receive signal and an output of the local oscillator are input to the first receive frequency converter, the receive signal is converted into a signal of a first intermediate frequency by the first receive frequency converter, the signal of the first intermediate frequency is input to the demodulator, and the output of the local oscillator at the local oscillator frequency is frequency-divided by the frequency divider and input to the demodulator, and the signal converted into the first intermediate frequency is demodulated into a baseband signal by the demodulator,

said circuit further comprising a transmit frequency converter and a modulator, wherein

the output of the local oscillator is input to the transmit frequency converter, an output of the frequency divider is input to the modulator to be modulated into a transmit intermediate frequency signal with a modulating signal, and the transmit intermediate frequency signal is input to the transmit frequency converter to be frequency-converted into a signal of a transmit frequency.

10. A radio circuit according to claim 9, wherein a frequency division number of the frequency divider is an integer N, a receive frequency or the transmit frequency is higher than an output frequency of the local oscillator, the local oscillator is a phase-locked loop frequency synthesizer circuit, and a phase comparison frequency is f×

N/(N+1) or {f×

N/(N+1)}/m, wherein f is the transmit and receive frequency channel spacing and m is an integer including 1.

11. A radio circuit according to claim 9, wherein a frequency division number of the frequency divider is an integer N, a receive frequency or the transmit frequency is lower than an output frequency of the local oscillator, the local oscillator is a phase-locked loop frequency synthesizer circuit, and a phase comparison frequency is f×

N/(N−

1) or {f×

N/(N−

1)}/m, wherein f is the transmit and receive frequency channel spacing and m is an integer including 1.

12. A radio circuit comprising a local oscillator at a local oscillator frequency, a frequency divider, a modulator and a local frequency converter, wherein

an output of the local oscillator at the local oscillator frequency is input to the frequency divider to be frequency-divided, the local frequency converter receives the output of the local oscillator and an output of the frequency divider to output a signal of a transmit frequency, and the modulator modulates an output of the local frequency converter with a modulating signal to output a signal of the transmit frequency,

said circuit further comprising a first receive frequency converter and a demodulator, wherein

a receive signal and the output of the local oscillator are input to the first receive frequency converter, the receive signal is converted into a signal of a first intermediate frequency by the first receive frequency converter, the signal of the first intermediate frequency is input to the demodulator, the output of the local oscillator is frequency-divided by the frequency divider and input to the demodulator, and the signal converted into the first intermediate frequency is demodulated into a baseband signal by the demodulator.

13. A radio circuit according to claim 12, wherein a frequency division number of the frequency divider is an integer N, a receive frequency or the transmit frequency is higher than an output frequency of the local oscillator, the local oscillator is a phase-locked loop frequency synthesizer circuit, and a phase comparison frequency is f×

N/(N+1) or {f×

N/(N+1}/m, wherein f is the transmit and receive frequency channel spacing and m is an integer including 1.

14. A radio circuit according to claim 12, wherein a frequency division number of the frequency divider is an integer N, a receive frequency or the transmit frequency is lower than an output frequency of the local oscillator, the local oscillator is a phase-locked loop frequency synthesizer circuit, and a phase comparison frequency is f×

N/(N−

1) or {f×

N/(N−

1)}/m, wherein f is the transmit and receive frequency channel spacing and m is an integer including 1.