Method and circuit for deriving a second clock signal from a first clock signal

1. A clock generation circuit for a dual communications technology system radio frequency (RF) station, including:

a digital clock synthesis circuit clocked by a first clock signal for a first communications technology RF system and adapted to generate an analog base clock signal of a predetermined frequency; and

means for deriving a second clock signal for a second communications technology RF system from an output of said digital clock synthesis circuit as a Nyquist image derived from said first clock signal.

2. A clock generation circuit for a dual communications technology system radio frequency (RF) station, including:

a digital clock synthesis circuit clocked by a first clock signal for a first communications technology RF system and adapted to generate an analog base clock signal of a predetermined frequency; and

means for deriving a Nyquist image derived from said first clock signal, said Nyquist image having the frequency of a second clack signal for a second communications technology RF system.

3. A method for deriving a second clock signal for a second communications technology system from a first clock signal of a first communications technology system, where a frequency of said second clock signal is greater than half of a frequency of said first clock signal, including:

clocking a direct digital clock synthesis circuit with said first clock signal of a first communications technology system to generate an analog base clock signal;

applying a phase step in said synthesis circuit such that a sum of a frequency of said analog base clock signal and the frequency of said first clock signal has the frequency of said second clock signal for a second communications technology system; and

deriving said second clock signal from an output of said digital clock synthesis circuit.

4. A method for deriving a second clock signal from a first clock signal according to claim 3 , wherein the frequency of said second clock signal is greater than the frequency of said first clock signal.

5. A method for deriving a second clock signal from a first clock signal according to claim 3 , wherein the frequencies of said clock signals are those used by different radio frequency communications systems.

6. A method for deriving a second clock signal from a first clock signal according to claim 3 , wherein said phase step is such that said base clock signal frequency represents a difference in frequency between said first clock signal and said second clock signal.