RF Oscillator Circuits with Low Phase Noise and Wide Frequency Tuning Range Performances in GaN-On-Si HEMT Technology

The GaN HEMT-based oscillator MMICs have being developed and designed in this project for S band and C band wireless communication based on the experiences of development of high-frequency and high-power semiconductor devices and the technique for microwave circuit design in Department of Electronics, Chang Gung University. To achieve the integrated transmitter and receiver chips for mobile communication systems, the performances of the oscillator circuits are investigated with wide frequency tuning range, high DC-to-RF conversion efficiency, low output phase noise, and high output power level. The 2.4 GHz and 5.2 GHz high-efficiency oscillators will be designed by using a high efficiency power amplifier with a proper on-chip or an external feedback network. The circuits will achieve an output power of 30 dBm and conversion efficiency over 40 %. The wide tuning range oscillator will be implemented based on a broadband amplifier. The frequency tuning range should be covering from 1 GHz to 5 GHz with an output power of 25 dBm. A 5.7 GHz ring oscillator MMIC with I/Q quadrature phase performance has been designed and fabricated by using GaN-on-Si HEMT process. The measured output power is 10 dBm without using output buffers. The free-running phase noise is -116 dBc/Hz@1 MHz. With using the injection locking technique, the phase noise can be improved to be -131 dBc/Hz@1 MHz. In order to accomplish the concept in this project, the relative performances of the high-efficiency and broadband power amplifiers have been also established. The design of 3.5 GHz high-efficiency power amplifier is based cascode circuit topology. The maximum output power of 4 W can be achieved with a power-added efficiency of 47 %. The broadband amplifier using Darlington circuit has a bandwidth ranging from 1 GHz to 5 GHz. The measured maximum output power approximates to 1 W.

Project ID:PB10207-1792
External Project ID:NSC102-2221-E182-070