ANALYSIS OF EFFECTIVE CAPACITANCE OF ONE-PORT S-BAND GaN HEMT NON-FOSTER NEGATIVE-REACTANCE CIRCUIT

This paper presents an analysis of the effective capacitance of one-port S-band gallium nitride high electron mobility transistor (GaN HEMT) non-Foster negative-reactance circuit. The analysis was carried out at S-band frequency ranges of 4.08 GHz to 4.11 GHz and 4.13 GHz to 4.17 GHz. The chosen frequency ranges are consistent with the frequency at which the simulated and fabricated non-Foster negative reactance circuit has negative reactance to frequency slope. The one-port non-Foster negative-reactance circuit was designed with Keysight Advanced Design System (ADS) Software and fabricated with FR_4 Microstrip substrate on printed circuit board with Copper conductor thickness of 1.5mm and measured with vector network analyzer (VNA). The circuit was designed with Cree CGHV4003F GaN HEMT biased with drain supply voltage of 20 V at quiescent drain-to-source (IDSq) current of 19 mA. The one-port S-band non-Foster negative-reactance circuit has measured effective capacitance of -5 pF to -26 pF and simulated effective capacitance of -0.16 pF to -0.17 pF from 4.08 GHz to 4.11 GHz. The measured effective capacitance from 4.13 GHz to 4.17 GHz ranges from -20 pF to -53 pF as the simulated effective capacitance ranges from -0.18 pF to -0.21 pF. This one-port non-Foster negative reactance circuit showed effective negative capacitance at the chosen frequency ranges at measurement and simulation.