High precision, low phase noise synthesizer with vector modulator

An apparatus for generating a modulated signal comprising:

• a modulator operative for receiving a first signal and input data signals, and modulating said first signal in accordance with said input data signals so as to p roduce a modulated reference signal;
• a first frequency divider coupled to an output of said modulator, said frequency divider operative to reduce the frequency of said modulated reference signal by a predetermined factor;
• a signal generator operative to produce a second signal;
• a first mixer having a first and second input, said first input coupled to an output of said first frequency divider and said second input coupled to an output of said signal generator, said first mixer operative to frequency translate said modulated reference signal by an amount equal to the frequency of said second signal to generate said modulated signal;
• a local oscillator for generating an rf signal;
• and
• a first phase lock loop for multiplying the frequency of said rf signal by a predetermined amount so as to generate said first signal, said first phase lock loop having an input for receiving said rf signal, and a feedback network comprising a second and third frequency divider coupled in series;
• and
• wherein said signal generator comprises:
• a direct digital synthesizer for generating a tunable signal, said synthesizer having a first and second input, said first input operative to receive a tuning frequency signal, said second input operative to receive a first reference signal;
• and
• a second phase lock loon for multiplying the frequency of said tunable signal by a predetermined amount so as to generate said second signal;
• and
• wherein said second phase lock loop comprises a feedback network including a second mixer having a first and second input, said first input coupled to an output of said first phase lock loop and said second input coupled to a second reference signal, said second mixer operative to frequency translate said second reference signal by an amount equal to the frequency of said output of said first phase lock loop.