Design of Ultra-Low Phase Noise and High Power Integrated Oscillator in $0.25~\mu{\rm m}$ GaN-on-SiC HEMT Technology

Abstract

A novel ultra-low phase noise and high power integrated oscillator is presented in this letter. The proposed oscillator, based on GaN-on-SiC high electron mobility transistor (HEMT) with 0.25 µm gate length and 800 µm gate width, delivers 21 dBm output power when biased at V GS = -3 V and V DD = 28 V. Phase noise was measured to be -112 dBc/Hz at 100 kHz offset and -135 dBc/Hz at 1 MHz offset from 7.9 GHz carrier, respectively. To the best of our knowledge, it achieves the lowest phase noise compared to other GaN HEMT based integrated oscillators. It is also comparable in performance to the state-of-the-art ultra-low phase noise oscillators designed in InGaP technology, while delivering more than 10 times higher output power. In addition, this oscillator also exhibits a minimum second harmonic suppression of 28.65 dBc and more than 60 dBc third harmonic suppression. The chip size is 1.1 × 0.6 mm 2 . The results show that the proposed oscillator has the potential to be used for both low phase noise and high power microwave source applications.

Design of an oscillator with low phase noise and medium output power in a 0.25 µm GaN‐on‐SiC high electron‐mobility transistors technology

“…As shown in Table 1, most GaN oscillators are designed mainly for low frequency applications because of the device limitation, such as the ones designed for C-band [6,8,10,12,14] and X-band [7,9,11,13], while there are a few designed for…”

“…Although the phase noise of this oscillator still needs to be further improved, it opens up a new examination on the design of oscillators in GaN HEMT technology for low voltage, moderate output power as well as low phase noise. It is also clearly shown in Table 1 that GaN oscillators with large tuning range can only achieve a phase noise of − 123 dBc/Hz [6], whereas those fixed frequency ones can achieve a phase noise as low as − 135 dBc/Hz [14]. In addition, varactors are not available in Cree's process design kit (PDK).…”

“…However, the DRO is usually bulky and costly compared with the monolithic oscillator. Therefore research on design of compact and low-cost monolithic oscillators with low phase noise have attracted extensive attention in the last years [1,[3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. To achieve low phase noise, heterojunction bipolar transistor (HBT) based designs are inherently better than the field effect transistor (FET) based ones because HBT device has inherently lower flicker noise corner frequency than the FET device [3].…”

“…To overcome this problem, gallium nitride (GaN) high electron-mobility transistors (HEMTs) have been recognised as high power and high frequency devices for next generation wireless, space, military and many other applications. The fundamental material properties of GaN HEMT enable a much higher voltage handling and better heat sinking capability compared with GaAs/InP and SiGe [6][7][8][9][10][11][12][13][14][15][16][17][18]. These advantages can enable monolithic oscillators to be realised with significant improvement in output power, thus potentially eliminating the need for additional power amplifiers.…”

“…In addition, simulators may also vary in their accuracy in predicting the phase noise. Although there are some excellent publications on the high power monolithic GaN HEMT oscillators in the literature [6][7][8][9][10][11][12][13][14][15][16][17], the achieved phase noise performance is still inadequate and thus requires further improvement.…”