A 2.4 GHz-Band 250 W, 60% Feedback-Type GaN-HFET Oscillator Using Imbalanced Coupling Resonator for Use in the Microwave Oven

Abstract

Circuit design techniques for enhancing an efficiency of the high power feedback-type GaN-HFET (Gallium Nitride Heterojunction Field Effect Transistor) oscillator for use in the microwave oven are shown in this paper, focusing primarily on the harmonic terminations for high efficiency of power amplifiers, the coupling factor to feedback circuits and the insertion phase adjustment of feedback loops. With the use of these circuit design techniques, an output power of 263 W and an efficiency of 61.3% have been successfully achieved at 2.44 GHz.

Design of ISM-Band High Power and High Efficiency Solid-State VCOs for Use in Next Generation Microwave Oven

“…Since Gain_osc differs depending on the device used, the optimal C1 and C2 were determined by analysis. As a result, C1 = 0.1pF and C2 = 0.3pF were obtained for the 200W_LD-MOSFET [12], and C1 =0.05pF and C2 = 0.3pF were obtained for the 50W_GaN-HFET [14].…”

“…The configuration of the feedback oscillator is shown in Fig. 1 [12]- [15]. It consists of (A) feedback circuit and (B) power amplifier.…”

“…We focus on the coupling capacitors of the resonator in the feedback circuit [13], [14]. There are a coupling capacitor (C1a) that picks up a part of the output signal of the amplifier, the filter that composed of coupling capacitors (C1b) and (C2) at both ends of the resonator that passes only the oscillation frequency, and the transmission line that adjust the feedback phase in the feedback circuit.…”

“…In the case of a 200W LD-MOSFET [12], the gain obtained by subtracting 3dB from the linear gain is defined as Gain_osc because the efficiency is high at P3dB (3dB gain compression). In the case of a 50W GaN-HFET [14], the gain obtained by subtracting 2dB from the linear gain is defined as Gain_osc because the efficiency is high at P2dB (2dB gain compression). Since Gain_osc differs depending on the device used, the optimal C1 and C2 were determined by analysis.…”

Study of high efficiency, low noise sputtered magnetron's cathode using GaN and SiC semiconductors for modulated microwave power transmission

“…A comparative analysis is summarized in Table 4 [25][26][27][28][29][30][31][32][33]. The proposed solution improves the efficiency significantly by 50% with the GaN and SiC plasma layers compared to the conventional counterpart.…”