Development of a high-power and high-efficiency HBT MMIC VCO

We present the design, implementation and measurement of a high power and high efficiency AlGaAs/GaAs HBT MMIC VCO. This VCO design represents the first demonstration of a VCO MMIC based on a systematic efficiency optimization technique. The fabricated 2.0 GHz VCO MMIC achieves a measured maximum efficiency of 34% and an maximum output power of 22.2 dBm, as well as a 200 MHz of frequency tuning range applicable for MMDS fixed wireless applications. In addition, a second harmonic suppression of 37 dBc or more is obtained across the entire frequency tuning range. The maximum output power of this VCO is comparable to that of the best reported VCO in the same frequency range (Prigent et al. 1995). However, the design presented in Prigent et al. is a VCO module with a high-Q cavity, unlike the MMIC implementation reported in this paper which is considerably more compact. Our VCO MMIC also offers a better efficiency compared to other state-of-the-art MMIC implementations with various processes and better output power without the use of any buffer amplifier.