Variable frequency oscillator having wide tuning range and low phase noise

Variable frequency oscillator comprising a first transistor and a second transistor;

• wherein said first transistor has a first terminal—collector—which is connected to a reference voltage, and a second terminal—emitter—which is connected to a first terminal of a first current source which second terminal is connected to ground, and a third terminal—base—connected to a first terminal of a first inductor and to a top terminal of a first capacitor, wherein said first capacitor has a bottom terminal which is connected to said second terminal—emitter—of said first transistor but also to a top terminal of a second capacitor having a bottom terminal being connected to ground;
• wherein said second transistor has a first terminal—collector—which is connected to a reference voltage, and a second terminal—emitter—which is connected to a first terminal of a second current source which second terminal) is connected to ground, and a third terminal—base—connected to a first terminal of a second inductor and to a top terminal of a third capacitor, wherein said third capacitor has a bottom terminal which is connected to said second terminal—emitter—of said second transistor and also to a top terminal of a fourth capacitor having a bottom terminal being connected to ground;
• wherein said first and second inductors have a second terminal which are connected via a circuit achieving variable capacitance, so as to form a circuit connecting in series all passive components composing the LC tank,
• so as to achieve a variable capacitance which can be used for performing a tuning of the oscillator;
• and
• wherein said second capacitor and said fourth capacitor are both connected to the physical ground thereby avoiding a 2nd harmonic common mode oscillation that might dominate over the differential fundamental one and might increase the phase noise.