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1. (WO2001017124) MULTI-BAND TRANSCEIVER HAVING MULTI-SLOT CAPABILITY
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Claims
1. A transceiver having simultaneous transmission and reception capability comprising:
a first local oscillator LOl that generates a signal having a frequency fwi',
a second local oscillator LO2 that generates a signal having a frequency fw2',
a receiver that receives a receive signal having a frequency fa, wherein^ is one of the sum or the difference of frequencies fai and fw2, the receiver comprising an image rejection mixer that mixes frequencies fai andfLo2 to generate a demodulating signal at the receive frequency fa, and a quadrature down converter that mixes the demodulating signal with the receive signal to produce baseband "I" and "Q" signals; and
a transmitter that transmits a transmit signal having a frequency fa, wherein fa is equal to fa minus a comparison frequency fa, the transmitter comprising a voltage-controlled oscillator (VCO) that generates the transmit signal, a mixer that mixes the transmit signal with the signal from the first local oscillator LOl to produce an IF signal having a
a quadrature mixer that modulates the IF signal with baseband "I" and "Q" signals, a first divider that divides fa by an integer M down to fa, a second divider that divides fw2 by an integer N down to fa, and a phase detector that compares the phases of the signals output by the first and second dividers and outputs a control voltage to the VCO.

2. A transceiver as claimed in claim 1, wherein fai is variable in relation to fa and fLo2 is fixed.
3. A transceiver as claimed in claim 2, wherein the receive and transmit signals are from one of first and second frequency bands, and wherein the image rejection mixer generates a demodulating signal having a frequency fa = fLOX - fL02 for receive signals in the first frequency band or a demodulating signal having a frequency fnx = Λoi + Λ02r receive signals in the second frequency band.

4. A transceiver as claimed in claim 3, wherein the first frequency band is

GSM and has a receive bandwidth of 925-960 MHz and a transmit bandwidth of 880-915 MHz, and the second frequency band is DCS and has a receive bandwidth of 1805-1880 MHz and a transmit bandwidth of 1710-1785 MHz.

5. A transceiver as claimed in claim 4, wherein local oscillator LOl has a bandwidth of 1375-1410 MHz in GSM and a bandwidth of 1330-1405 MHz in DCS.

6. A transceiver as claimed in claim 5, wherein local oscillator LO2 has a fixed frequency of 450 MHz in GSM and a fixed frequency of 475 MHz in DCS.

7. A transceiver as claimed in claim 3, wherein the transmitter mixer generates an IF signal having a frequency fa = fW2 + fCF for transmit signals in the first frequency band or an IF signal having a frequency fa = fL02 - fCF for transmit signals in the second frequency band.

8. A transceiver as claimed in claim 7, wherein CF=45 MHz for transmit signals in the first frequency band and αM)5 MHz for transmit signals in the second frequency band.

9. A transceiver as claimed in claim 7, wherein f/F=:495 MHz for transmit signals in the first frequency band and
MHz for transmit signals in the second frequency band.

10. A transceiver as claimed in claim 3, wherein the first divider divides fa by an integer M=N+I for transmit signals in the first frequency band and by an integer M=N-1 for transmit signals in the second frequency band.

11. A transceiver as claimed in claim 10, wherein N=10 for signals in the first frequency band and N=5 for signals in the second frequency band.

12. A transceiver as claimed in claim 3, wherein the image rejection mixer comprises:
first and second phase shifters and first, second, third and fourth mixers, wherein the first phase shifter receives a signal from oscillator LOl and outputs an in-phase signal to the first and second mixers and a 90° phase-displaced signal to the third and fourth mixers, and the second phase shifter receives a signal from oscillator LO2 and outputs an in-phase signal to the second and fourth mixers and a 90° phase-displaced signal to the first and third mixers; and
first and second combiners that may be set to perform a difference or a summing operation, wherein the first combiner receives inputs from the first and second mixers and outputs a demodulating signal, and wherein the second combiner receives inputs from the third and fourth mixers and outputs a 90° phase-displaced demodulating signal.

13. A transceiver as claimed in claim 12, wherein the quadrature downconverter comprises an "I" demodulator and a "Q" demodulator, and wherein the "I" demodulator receives the receive signal and the demodulating signal from the first combiner of the image rejection mixer, and wherein the "Q" demodulator receives the receive signal and the 90° phase-displaced signal from the second combiner.

14. A transceiver as claimed in claim 1, wherein the receiver further comprises at least one low noise amplifier that amplifies the receive signal before it is supplied to the quadrature down converter.

15. A transceiver as claimed in claim 1, wherein the receiver further comprises a baseband gain and filter chain for filtering and amplifying the baseband "I" and "Q" signals generated by the quadrature down converter.

16. A transceiver as claimed in claim 3, wherein the quadrature mixer comprises a phase shifter, and "I" and "Q" modulators, and wherein the phase shifter splits the IF signal into an in-phase signal that is supplied to the "I" modulator and a 90° phase-displaced signal that is supplied to the "Q" modulator.

17. A transceiver as claimed in claim 3, and further comprising another VCO for generating transmit signals in the second frequency band, and a switch for selecting between the two VCOs.

18. A transceiver as claimed in claim 3, and further comprising a charge pump coupled to the phase detector that generates a control current based on the control voltage output by the phase detector, and a loop filter that receives the control current and develops a control signal that is applied to the VCO.

19. A multi-band transceiver for receiving and transmitting signals within a selected one of at least two frequency bands, transmission and reception occurring simultaneously and within the same time slot of a TDMA frame, the transceiver comprising:
a first local oscillator LOl that selectively oscillates within a bandwidth corresponding to the selected frequency band and outputs a signal having a frequency fwi,' a second local oscillator LO2 that selectively oscillates at a frequency corresponding to the selected frequency band and outputs a signal having a frequency f ϊ, a receiver that receives a receive signal having a frequency fa and mixes the signals from the first and second local oscillators to generate a demodulating signal having a frequency fa, wherein fa = fWi ± fW2 ; and
a transmitter having a loop architecture and comprising a VCO that generates a transmit signal having a transmit frequency fa equal to^ minus a comparison frequency fcF, a mixer that mixes the signal from the first local oscillator with the transmit signal to generate an IF signal having a frequency fa = fL02 ± fCF , a quadrature mixer that modulates the IF signal with baseband "I" and "Q" signals, and a phase detector that compares the phases of the IF signal and the signal from the second local oscillator and outputs a control voltage to the VCO.

20. A multi-band transceiver as claimed in claim 19, and further comprising a first divider coupled between the quadrature mixer and phase detector that divides the frequency of the IF signal by an integer M, and a second divider coupled between oscillator LO2 and the phase detector that divides the frequency of the LO2 signal by an integer N.

21. A multi-band transceiver as claimed in claim 20, wherein N=M±I .

22. A method for simultaneously transmitting and receiving signals comprising the following steps:
(a) generating two local oscillation (LO) signals;
(b) receiving a receive signal;
(c) demodulating the receive signal using the LO signals;
(d) generating a transmit signal;
(e) modulating the transmit signal using one of the LO signals;
(f) aligning the phase of the transmit signal using the other of the LO signals; and
(g) transmitting the modulated transmit signal,
wherein receive steps (b)-(c) are performed repetitively and simultaneously with transmit steps (d)-(g).

23. A method as claimed in claim 22, wherein:
in step (a), a first local oscillation signal LOl having a frequency fai and a second local oscillation signal having a frequency fw2 are generated;

in step (b), the receive signal has a frequency fa; and
in step (c), a demodulating signal having a frequency fa = fLOl ± fL02 is generated.

24. A method as claimed in claim 23, wherein:
in step (d), the transmit signal has a frequency fa = fa - fCF , wherein fap is a constant comparison frequency.

25. A method as claimed in claim 24, wherein:
in step (e), an IF signal having a frequency fa = fLm - fa or fa = fa - fW] is generated by mixing the transmit signal and the LOl signal, and the IF signal is modulated with baseband "I" and "Q" modulation.

26. A method as claimed in claim 25, wherein:
in step (f), fa is divided by an integer M to generate a signal at the comparison frequency fa, andfw2 is divided by an integer N=M±I to generate another signal at the comparison frequency fa, and the phases of the two signals at the comparison frequency are compared.

27. A method for simultaneously transmitting and receiving signals comprising the following steps:
(a) generating a first local oscillation signal LOl having a frequency fai;
(b) generating a second local oscillation signal LO2 having a frequency f ϊ,
(c) receiving a receive signal having a frequency fa;

(d) mixing signals LOl and LO2 to generate a demodulating signal having a

(e) mixing the demodulating signal and the receive signal to generate baseband "I" and "Q" signals;
(f) generating a transmit signal having a frequency fa;
(g) mixing the transmit signal and the LOl signal to generate an IF signal having a frequency fa;
(h) modulating the IF signal with baseband "I" and "Q" signals;
(i) dividing the frequency of the IF signal^- down to a comparison frequency fa;
(j) dividing the frequency of the LO2 signal fw2 down to the comparison frequency/cF;
(k) comparing the phases of the divided IF and LO2 signals and adjusting the frequency of the transmit signal if necessary; and
(1) transmitting the modulated transmit signal,
wherein receive steps (c)-(e) and transmit steps (f)-(l) are performed within the same time slot of a TDMA frame.

28. A method as claimed in claim 27, and further comprising the step of selecting a frequency band for transmission and reception.

29. A method as claimed in claim 28, wherein the frequency band is selecting from the group consisting of GSM, having a receive bandwidth of 925-960 MHz and a transmit bandwidth of 880-915 MHz, and DCS, having a receive bandwidth of 1805-1880

MHz and a transmit bandwidth of 1710-1785 MHz.

30. A method as claimed in claim 29, wherein in step (a), if GSM is selected, LOl is within a frequency band of 1375-1410 MHz, and if DCS is selected, LOl is within a frequency band of 1330-1405 MHz.
31. A method as claimed in claim 29, wherein in step (b), if GSM is selected, LO2 has a frequency of 450 MHz, and if DCS is selected, LO2 has a frequency of 475 MHz.

32. A method as claimed in claim 29, wherein in step (d), mixing signals LOl and LO2 creates a difference frequency fa = f - fL02 and a sum frequency

ΛT = Λoi + Λ02 ' an(l wherein if GSM is selected, the demodulating signal is the difference frequency and the sum frequency is suppressed, and if DCS is selected, the demodulating signal is the sum frequency and the difference frequency is suppressed.

33. A method as claimed in claim 29, wherein in step (f), the transmit signal has a frequency fa = fa - fa >
MHz if GSM is selected
MHz if DCS is selected.

34. A method as claimed in claim 29, wherein in step (g), fa = f - fa if GSM is selected and fa = fa - fWi if DCS is selected.

35. A method as claimed in claim 34, wherein fa = fW2 + fCF if GSM is selected and fa = fW2 - fCF if DCS is selected.

36. A method as claimed in claim 29, wherein in step (i), the frequency of the IF signal is divided by 11 if GSM is selected and is divided by 4 if DCS is selected.

37. A method as claimed in claim 29, wherein in step (j), the frequency of the LO2 signal is divided by 10 if GSM is selected and is divided by 5 if DCS is selected.

38. A wireless handset comprising a transceiver as claimed in claim 1.

39. A wireless handset comprising a transceiver as claimed in claim 19.