Abstract: A frequency synthesizer is described that includes: a voltage controlled oscillator, VCO; a VCO bias circuit, operably coupled to the VCO and configured to provide a controllable bias current of the VCO; a temperature sensor, located in the frequency synthesizer, configured to determine an operating temperature of the frequency synthesizer; an analog-to-digital converter, ADC, operably coupled to the temperature sensor and configured to provide a digital representation of the determined operating temperature; and a bias control circuit operably coupled and configured to provide a bias control signal to the VCO bias circuit based on the determined operating temperature of the frequency synthesizer. The VCO bias circuit is configured to adjust the controllable bias current applied to the VCO based on the bias control signal.

Abstract: A frequency synthesizer (230) is described that includes: a voltage controlled oscillator, VCO (330); a VCO bias circuit (370), operably coupled to the VCO (330) and configured to provide a controllable bias current (384) of the VCO (330); a temperature sensor (372) located in the frequency synthesizer (230) and configured to determine an operating temperature of the frequency synthesizer (230); an analog-to-digital converter, ADC (376), operably coupled to the temperature sensor (372) and configured to provide a digital representation (378) of the determined operating temperature; and a bias control circuit (380) operably coupled to the ADC (376) and the VCO bias circuit (370) and configured to provide a bias control signal (382) to the VCO bias circuit (370) based on the determined operating temperature of the frequency synthesizer (230). The VCO bias circuit (370) is configured to adjust the controllable bias current (384) applied to the VCO based on the bias control signal (382).

Abstract: The present application relates to a differential Colpitts voltage-controlled oscillator (VCO) circuit, which comprises a pair of transistors with control terminals biased by a common biasing voltage and a pair of couplers arranged to cross-couple corrector/drain of the transistors and the base/gate of the differential transistors. The pair of couplers have a coupling factor kc, which used to enhance the transconductance of the transistor pair, therefore can be used for power consumption reduction and phase noise minimalization.

Abstract: The present application relates to a differential oscillator circuit. The differential oscillator circuit comprises a pair of transistors with control terminals biased by a common biasing voltage. The differential oscillator circuit further comprises a transformer having a primary coil coupled between first current terminals of the transistors and a secondary coil coupled in a closed series circuit with two varactors, which are arranged for being tuned by a first common tuning voltage. The differential oscillator circuit further comprises a series circuit comprising two further varactors coupled in series to second current terminals of the transistors. The two further varactors are arranged for being tuned by a second common tuning voltage.