| 摘要 |
A wireless communication unit (100) comprises a voltage controlled oscillator (123) having an active device (450) operably coupled to a first variable capacitance (425) to provide a variable capacitance value based on an applied steering line voltage, and a feedback network comprising a resonator (475), operably coupled to an output of the active device, for feeding power back to an input of the active device to sustain oscillations (123). Notably, a second variable capacitance is operably coupled to receive a control voltage from the steering line (405) and located between the resonator (475) and the active device (450). <??>The provision of a second variable capacitance located as described enables a VCO circuit to operate over a wider bandwidth with the same tuning voltages, say around 15% of the VCO's centre frequency. This is achieved due to gain margin tuning applied to the resonator and second variable capacitor of the VCO circuit. <IMAGE> |
