A Hybrid Bipolar Wideband VCO with Linearized Tuning Behaviour for a New Generation TTC Transponder

This paper presents a wideband voltage-controlled oscillator (VCO) using hybrid technology based on bipolar transistors for a new generation TTC Transponder. The VCO is based on microstrip three-pole combline bandpass filter with just one varactor diode. The bandpass filter is embedded into the feed-back loop to treat as a frequency stabilization element. The VCO delivered 4.63 dBm maximum output power at 3.4 GHz with a current consumption of 17.4 mA for a supply voltage of 3 V and it has a tuning range achieved from 600 MHz being the frequency range from 2.8 GHz to 3.4 GHz. The developed VCO with three pole combline filter is experimentally demonstrated at 3.4 GHz with a phase noise of − 126 dBc/Hz at 1 MHz offset frequency. In addition, over this frequency range, all the phase noises measured at 1 MHz are better than −118 dBc/Hz.