Dependence of GaN HEMT Millimeter-Wave Performance on Temperature

This paper presents extensive thermal characterization of recently fabricated high-performance millimeter-wave GaN/SiC devices from four sources across temperature (-25°C to + 125°C). The changes with temperature for: output power at millimeter-wave frequencies (P
_out
), pinchoff voltage (V
_p
), knee-voltage (V
_k
), onresistance (R
_on
), power-added efficiency (PAE), saturated drain current (I
_dss
), power gain (G), and transconductance (g
_m
) are measured, statistics studied, and correlations investigated. Temperature-coefficients are established for P
_out
, V
_p
, V
_k
, R
_on
, PAE, I
_dss
, G, and g
_m
in GaN technology. The main findings are: 1) P
_out
's temperature dependence can be negative or positive, opposite of G's and I
_dss
's strong negative temperature dependence, and 2) the pinchoff voltage's dependence on temperature is very weak. The results obtained provide monolithic microwave integrated circuit designers with key information required for meeting performance over a wide temperature range.