Patent ID: 8766730

Claim:
A frequency tunable signal source comprising: a first oscillator for outputting a first signal (S1) having a first frequency (F1) and for outputting a second signal (s1′) having a frequency (F1′) that is a harmonic of the first frequency; a second oscillator for outputting a third signal (s2) having a third frequency (F2) and for outputting a fourth signal (s2′) having a frequency (F2′) that is a harmonic of the third frequency; a mixing circuit having a first input port, a second input port, a third input port, and an output port; a plurality of switches comprising: a first switch for switchably connecting s1 with the first input port of the mixing circuit, a second switch for switchably connecting s2 with the second input port of the mixing circuit, a third switch for switchably connecting s1′ with the first input port of the mixing circuit, and a fourth switch for switchably connecting s2′ with the second input port of the mixing circuit; a control unit for controlling said first, second, third and fourth switches; a third oscillator having an output port connected to the third input port of the mixing circuit and for outputting via its output port a fifth signal (s3), wherein at least one of said oscillators is a voltage controlled oscillator (VCO).