An X-band InGaP/GaAs Hetero-junction Bipolar Transistor Based Microwave Integrated Circuit Differential Voltage Controlled Oscillator for Satellite Communications

Abstract

This paper mainly focuses on the InGaP/GaAs hetero-junction bipolar transistor (HBT) which is fully based on integrated X-band monolithic microwave integrated circuit (MMIC) differential voltage controlled oscillator (VCO). This VCO is designed and fabricated with HBT tripler circuit techniques for triple multiplication of frequency component of core VCO output. The HBT-based differential VCO circuitry consists of a differential VCO and two triplers. The VCO design is concentrated in high oscillation frequency with the low phase noise by using the tripler circuit. The tripler is the smallest in size, with the lowest power consumption and X-band application frequency. The lowest frequency characteristic enables MMIC tripler differential VCO to be implemented in phase locked loop (PLL) circuit. This approach solves the problem of stable local oscillator (LO) signal. The differential VCO is based on the capacitive cross-coupled differential topology. The core differential VCO achieves the oscillation frequency of 3.583 GHz with the output power of 3.65 dBm, the phase noise of −96.7 dBc at 100 kHz offset and −118.85 dBc at 1 MHz offset at 2.9 V and 30 mA bias condition. At 5 dBm input power, the tripler’s conversion loss is less than 30 dB with bias condition as 3 V and 26 mA. The tripler diferential VCO generates the oscillation frequency of 10.75 GHz with the output power of −25 dBm. The total size of fabricated MMIC tripler differential VCO is 995 × 850 ¼m2 area.