Patent ID: 7812679

Claim:
A method of generating an output signal in a Multi-band frequency Generation Unit, the method comprising the steps of: operating the Multi-band frequency Generation Unit within an Association of Public-safety Communications Officials project 25 (APCO25) radio, selecting an intermediate frequency (IF) and a frequency divider value (M); providing a plurality of selectable VCOs based on the selected IF and the frequency divider value (M) to cover multiple spectrum ranges having narrow channel spacing, the plurality of selectable VCOs having VCO phase noise meeting the APCO25 radio requirements; selecting a VCO frequency band output from the plurality of selectable VCOs; generating a reference frequency; dividing a VCO output frequency using a programmable feedback frequency divider operating at a loop divider value (N) to generate a divided VCO feedback frequency and dividing the reference frequency using a programmable reference divider to generate a divided reference frequency; applying the divided reference frequency and the divided VCO feedback frequency to a phase detector to optimize phase noise in the output signal; generating sink/source control output signals at the phase detector; applying the sink/source control output signals to a programmable charge pump; generating a charge pump output current, wherein the charge pump output current is selected in conjunction with the divided reference frequency and the loop divider value (N) to optimize phase noise in the output signal; filtering the charge pump output current using a loop filter having the maximum allowable loop filter bandwidth based on fixed elements to produce a control voltage; applying the control voltage to the plurality of selectable VCOs thereby steering selected desired VCO frequency band output to generate a phase locked VCO output signal; and generating an output signal based on the phase locked VCO output signal.