Patent ID: 7003049

Claim:
A method for modulating a fractional-N synthesizer (F-N synthesizer) in response to applied sequences of in-phase (I) and quadrature (Q) analog modulation signals, said F-N synthesizer comprising a loop divider having a variable fractional divisor, the method comprising: comparing said sequence of I analog modulation signals with a first plurality of threshold values at successive time intervals, thereby to generate a sequence of I digital output signals, said sequence of I digital output signals corresponding to respective relationships between said sequence of I analog modulation signals and said first plurality of threshold values at said successive time intervals; comparing said sequence of Q analog modulation signals with a second plurality of threshold values at successive time intervals, thereby to generate a sequence of Q digital output signals, said sequence of Q digital output signals corresponding to respective relationships between said sequence of Q analog modulation signals and said second plurality of threshold values at said successive time intervals; transforming said sequences of I and Q digital output signals into a sequence of digital modulation signals in accordance with a predetermined relationship between values of said sequences of I and Q digital output signals over consecutive time intervals; and modifying said variable fractional divisor in accordance with said sequence of digital modulation signals.