Patent ID: 7579916

Claim:
A frequency synthesizer comprising: an input large step frequency source suitable for generating a large step frequency; a variable frequency source suitable for generating a small step frequency; a first phase detector; a first voltage controlled oscillator; a first mixer mixing the large step frequency and the small step frequency to generate a difference mix including non-uniform frequency steps and coherent spurious content; a second phase detector; a feedback loop, the feedback loop including; a second voltage controlled oscillator suitable for receiving an output of the second phase detector; and at least two frequency divide circuits, further including a first frequency divide circuit and a second frequency divide circuit coupled to the second phase detector to selectively produce one of a plurality of offset frequencies; a second mixer including a first input operably coupled to an input of the second phase detector, a second input coupled to an output of the first frequency divide circuit, and a third input suitable for receiving an input from the second frequency divide circuit; and wherein said input large step frequency and said small step frequency are suitable for combining to form an output frequency, second voltage controlled oscillator is in said feedback loop and said feedback loop is suitable for receiving the difference mix of the small step variable frequency and the large step frequency.