On-channel transceiver architecture in a dual band mobile phone

• US 5,890,051 A
• Filed: 03/17/1998
• Issued: 03/30/1999
• Est. Priority Date: 11/19/1997
• Status: Expired due to Term

• Current Assignee: Unwired Planet LLC (JP Morgan Chase & Co)
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Boesch, Ron, Gore, Charles, Hadjichristos, Aristotle, Schlang, Jeffrey
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Orgad, Edan
• Application Number:
  US09/042,554
• Time in Patent Office: 378 Days
• Field of Search: 455/76, 455/315, 455/75, 455/86, 455/189.1, 455/188.1, 455/260, 455/84, 455/553, 455/168.1, 455/147, 455/208, 455/255, 455/318, 375/219
• US Class Current: 455/76
• CPC Class Codes: H03D 7/163 the local oscillations of at least two of the frequency changers being derived from a single oscillator
• 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 1/006 using switches for selecting the desired band H04B1/0057 takes precedence
• CPC Class Codes: H04B 1/405 with multiple discrete channels

Abstract

According to a second embodiment of the invention, a mobile phone receiver comprises a first down converter using a first local oscillator frequency which can be tuned in frequency steps by a programmable digital frequency synthesizer PLL which is locked to a reference frequency. The first down converter converts received signals to a first IF for filtering. A second down converter using a second local oscillator converts first IF signals to a second IF. The second local oscillator frequency is generated using a second digital frequency synthesizer PLL which locks the second oscillator to the reference frequency. A third down converter mixes the transmit frequency with the first local oscillator frequency to produce a lock frequency. A third digital frequency synthesizer PLL compares the lock frequency and the reference frequency to control generation of the transmit frequency.

Claims

1. A radio transmitting and receiving apparatus for generating a signal for transmission on a transmit frequency and for receiving a signal on a receive frequency, comprising:

a first downconvertor for mixing said received signal with a first local oscillator frequency signal and converting it to a first intermediate frequency signal;

a second downconvertor for mixing said first intermediate frequency signal with a second local oscillator frequency signal and converting it to a second intermediate frequency;

reference means for providing a reference frequency signal;

first local oscillator frequency synthesizer means having a first input for said first local oscillator frequency signal and a second input for said reference frequency signal and in dependence thereon producing a control signal to control said first local oscillator to produce the desired first local oscillator frequency signal;

second local oscillator frequency synthesizer means having a first input for said second local oscillator frequency signal and a second input for said reference frequency signal and producing in dependence thereon a control signal to control said second local oscillator to produce the desired second local oscillator frequency signal;

transmit oscillator means for generating a transmit frequency signal;

transmit downconvertor means for mixing the transmit frequency signal with the first local oscillator signal to produce a lock frequency signal;

transmit synthesizer means having a first input for the lock frequency signal and a second input for the reference frequency signal and in dependence thereon producing a control signal for the transmit oscillator means to control the transmit frequency signal.

2. The apparatus of claim 1, further comprising a frequency doubler for doubling said first local oscillator frequency signal input to said first local oscillator frequency synthesizer means, wherein said first local oscillator frequency synthesizer means selects said first local oscillator frequency signal or the doubled first oscillator frequency for low band operation and high band operation, respectively.

3. The apparatus of claim 1, wherein the first down converter mixes said received signal with the first local oscillator frequency signal for low band operation and mixes said received signal with a doubled first oscillator frequency signal for high band operation.

4. The apparatus of claim 1, further comprising a frequency doubler for doubling the transmit frequency signal for high band operation.

5. The apparatus of claim 1, further comprising a frequency divider for dividing the transmit frequency signal for low band operation.

6. The apparatus of claim 1, further comprising frequency multipliers for multiplying the transmit frequency signal for low band operation and/or high band operation.

7. The apparatus of claim 1, further comprising frequency dividers for dividing the transmit frequency signal for low band operation and/or high band operation.

8. The apparatus of claim 1, further comprising a filter for filtering the lock frequency signal.

9. The apparatus of claim 1, further comprising a modulator for modulating the transmit frequency signal to produce the signal for transmission.

10. The apparatus of claim 1, further comprising a variable gain amplifier for amplifying the transmit frequency signal to produce the signal for transmission.

11. A method for generating a signal for transmission on a transmit frequency and for receiving a signal on a receive frequency, comprising the steps of:

mixing said received signal with a first local oscillator frequency signal to produce a first mixed signal;

converting said first mixed signal to a first intermediate frequency signal;

mixing said first intermediate frequency signal with a second local oscillator frequency signal to produce a second mixed signal;

downconverting said second mixed signal to a second intermediate frequency;

comparing said first local oscillator frequency signal and a reference frequency signal and producing in dependence thereon a control signal to control the production of the desired first local oscillator frequency signal;

comparing said second local oscillator frequency signal and said reference frequency signal and producing in dependence thereon a control signal to control production of the desired second local oscillator frequency signal;

generating a transmit frequency signal;

mixing the transmit frequency signal with the first local oscillator signal to produce a lock frequency signal;

comparing the lock frequency signal and the reference frequency signal and in dependence thereon producing a control signal to control the generation of the transmit frequency signal.

12. The method of claim 11, further comprising the steps of:

doubling said first local oscillator frequency signal; and

selecting the first local oscillator frequency signal or the doubled first local oscillator frequency signal for comparison with the reference frequency signal for low band operation and high band operation, respectively.

13. The method of claim 11, wherein said received signal is mixed with the first local oscillator frequency signal for low band operation, and said received signal is mixed with a doubled first oscillator frequency signal for high band operation.

14. The method of claim 11, further comprising a step of doubling the transmit frequency signal for high band operation.

15. The method of claim of claim 11, further comprising a step of dividing the transmit frequency signal for low band operation.

16. The method of claim 11, further comprising a step of multiplying the transmit frequency signal for low band operation and/or high band operation.

17. The method of claim 11, further comprising a step of dividing the transmit frequency signal for low band operation and/or high band operation.

18. The method of claim 11, further comprising a step of filtering the lock frequency signal.

19. The method of claim 11, further comprising a step of modulating the transmit frequency signal to produce the signal for transmission.

20. The method of claim 11, further comprising a step of amplifying the transmit frequency signal for transmission.