Unified dual-mode GSM/UMTS clock

1. A unified dual-mode global standard for mobile communication (GSM)/universal mobile telecommunication systems (UMTS) clock comprising:

a reference clock configured to generate a reference clock signal;

a local oscillator (LO) configured to generate a single LO signal based on the reference clock signal;

at least one frequency divider configured to selectively generate either (1) a GSM clock signal by converting a frequency of the LO signal by a predetermined integer factor or (2) a UMTS clock signal by converting the frequency of the LO signal by a predetermined integer factor, wherein both the GSM clock signal and the UMTS clock signal are generated based on the reference clock signal;

wherein the LO is configured to generate the LO signal at a frequency of 312 MHz and a frequency divider comprises a rate matching unit configured to convert the LO signal to a frequency that is an integer multiple of 3.84 MHz;

wherein the rate matching unit comprises:

a 6-bit counter configured to count pulses of the LO signal and to generate a 6-bit binary number;

a NAND gate configured to generate an output based on the 6-bit binary number; and

a D flip-flop configured such that an enable port is driven by an output of the NAND gate, the LO signal clocks the D flip-flop and a Q output of the D flip-flop, which is used as a clock signal for a UMTS timing manager, is fed back to an input of the D flip-flop.

2. The dual-mode GSM/UMTS clock of claim 1 wherein the reference clock is configured to generate the reference clock signal having a frequency of one of 13 MHz, 15.36 MHz, 19.2 MHz, 26 MHz and 38.4 MHz.

3. The dual-mode GSM/UMTS clock of claim 1 wherein the at least one frequency divider comprises a first frequency divider configured to clock an analog-to-digital converter (ADC) and a second frequency divider configured to clock a digital-to-analog converter (DAC).

4. The dual-mode GSM/UMTS clock of claim 3 wherein the frequency divider further comprises a third frequency divider configured to generate a clock signal for a GSM timing manager.

5. The dual-mode GSM/UMTS clock of claim 3 wherein the frequency divider further comprises a fourth frequency divider configured to generate the clock signal for the UMTS timing manager.

6. The dual-mode GSM/UMTS clock of claim 1 wherein the LO is configured to generate the LO signal at a frequency of 312 MHz.

7. A dual-mode transceiver for global standard for mobile communication (GSM) and universal mobile telecommunication (UMTS), the transceiver comprising:

a unified dual-mode GSM/UMTS clock configured to generate a GSM clock signal and a UMTS clock signal based on a common reference clock signal;

a transmitter configured to process GSM baseband data and UMTS baseband data to be transmitted based on the GSM clock signal and the UMTS clock signal, respectively; and

a receiver configured to process received GSM baseband data and UMTS baseband data based on the GSM clock signal and the UMTS clock signal, respectively,

wherein the unified dual-mode GSM/UMTS clock comprises:

a reference clock configured to generate the common reference clock signal;

a local oscillator (LO) configured to generate a single LO signal based on the common reference clock signal; and

at least one frequency divider configured to selectively generate either (1) the GSM clock signal by converting a frequency of the LO signal by a predetermined integer factor or (2) the UMTS clock signal by converting a the frequency of the LO signal by a predetermined integer factor;

wherein the LO is configured to generate the LO signal at a frequency of 312 MHz and the fourth frequency divider comprises:

a rate matching unit configured to convert the LO signal to a frequency that is integer multiple of 3.84 MHz; and

a divider configured to divide an output of the rate matching unit by a second predetermined factor

wherein the rate matching unit comprises:

a 6-bit counter configured to count pulses of the LO signal and to generate a 6-bit binary number;

a NAND gate configured to generate an output based on the 6-bit binary number; and

a D flip-flop configured such that an enable port is driven by an output of the NAND gate, the LO signal clocks the D flip-flop and a Q output of the D flip-flop, which is used as the clock signal for the UMTS timing manager, is fed back to an input of the D flip-flop.

8. The dual-mode transceiver of claim 7 , wherein the reference clock is configured to generate the common reference clock signal having a frequency of at least one of 13 MHz, 15.36 MHz, 19.2 MHz, 26 MHz and 38.4 MHz.

9. The dual-mode transceiver of claim 7 , wherein the frequency divider comprises a first frequency divider configured to clock an analog-to-digital converter (ADC) in the receiver and a second frequency divider configured to clock a digital-to-analog converter (DAC) in the transmitter.

10. The dual-mode transceiver of claim 9 further comprising:

a GSM timing manager; and

a third frequency divider configured to generate a clock signal for the GSM timing manager.

11. The dual-mode transceiver of claim 9 further comprising:

a UMTS timing manager; and

a fourth frequency divider configured to generate a clock signal for the UMTS timing manager.

12. The dual-mode transceiver of claim 7 , wherein the LO is configured to generate the LO signal at a frequency of 312 MHz.

13. The dual-mode transceiver of claim 7 further comprising an interpolator and a decimator configured to match frequencies of the UMTS baseband signal and the UMTS clock signal.

14. The dual-mode transceiver of claim 7 further comprising an interpolator and a decimator configured to match frequencies of GSM baseband signal and the GSM clock signal.