A physical investigation of large-signal dynamic output capacitance and energy loss in GaN-on-Si power HEMTs at high-frequency applications

In this paper, a high-power amplifier integrated circuit (IC) in gallium-nitride (GaN) on silicon (Si) technology is presented at a W-band (75–110 GHz). In order to mitigate the losses caused by relatively high loss tangent of Si substrate compared to silicon carbide (SiC), low-impedance microstrip lines (20–30 Ω) are adopted in the impedance matching networks. They allow for the impedance transformation between 50 Ω and very low impedances of the wide-gate transistors used for high power generation. Each stage is matched to produce enough power to drive the next stage. A Lange coupler is employed to combine two three-stage common source amplifiers, providing high output power and good input/output return loss. The designed power amplifier IC was fabricated in the commercially available 60 nm GaN-on-Si high electron mobility transistor (HEMT) foundry. From on-wafer probe measurements, it exhibits the output power higher than 26.5 dBm and power added efficiency (PAE) higher than 8.5% from 88 to 93 GHz with a large-signal gain > 10.5 dB. Peak output power is measured to be 28.9 dBm with a PAE of 13.3% and a gain of 9.9 dB at 90 GHz, which corresponds to the power density of 1.94 W/mm. To the best of the authors’ knowledge, this result belongs to the highest output power and power density among the reported power amplifier ICs in GaN-on-Si HEMT technologies operating at the W-band.

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Demonstration of Superior Static, Dynamic, and Short-Circuit Performance of 1.2 kV 4H-SiC Split-Gate Octagonal Cell MOSFETs Compared with Linear, Square, and Hexagonal Topologies

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1004.783 ◽

2020 ◽

Vol 1004 ◽

pp. 783-788

Author(s):

Ki Jeong Han ◽

Ajit Kanale ◽

B. Jayant Baliga ◽

Subhashish Bhattacharya

Keyword(s):

Energy Loss ◽

High Frequency ◽

Figure Of Merit ◽

Short Circuit ◽

Electrical Characteristics ◽

Circuit Performance ◽

Switching Performance ◽

Switching Energy ◽

Cell Topology ◽

Linear Cell

The electrical characteristics of the 1.2-kV rated 4H-SiC accumulation-channel split-gate octagonal cell MOSFET (SG-OCTFET) are experimentally compared with linear, square, hexagonal, octagonal, and compact-octagonal cell topologies. The specific on-resistance of the SG-OCTFET is 52% larger than the conventional linear cell topology. However, the SG-OCTFET has: (i) high-frequency figure-of-merit HFFOM[Ron×Cgd] 9.4×, 6.1×, 2.6×, 2.0×, and 1.8× superior to the square, hex, linear, octagonal, and compact-octagonal cells; (ii) fastest switching performance among all cell topologies, with 26% smaller switching energy loss than the conventional linear cell topology; and (iii) short circuit capability 1.5× longer than the conventional linear cell topology. The SG-OCTFET device is therefore an optimum candidate for high frequency applications of SiC MOSFETs.

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