Large signal linearity enhancement of AlGaN/GaN high electron mobility transistors by device-level V<inf>t</inf> engineering for transconductance compensation

AlGaN/GaN-Based Laterally Gated High-Electron-Mobility Transistors With Optimized Linearity

“…) are also used to evaluate device linearity, as shown in [29] and [30]. Smaller g m and g m indicate a better second-order voltage intercept point, VIP 2 (i.e., extrapolated gate voltage amplitudes at which the second harmonic becomes equal to the fundamental tone in the device's drain current), third-order voltage intercept point, VIP 3 (i.e., extrapolated gate voltage for third-order harmonic) and IMD 3 (i.e., third-order intermodulation distortion), performances [29].…”

Influence of fin width and gate structure on the performance of AlGaN/GaN fin‐shaped HEMTs

“…Compared with GaN‐based trigate fin‐shaped HEMTs, the absence of the top gate contact in GaN‐based dual‐gate fin‐shaped HEMTs makes it more important for the gate on the sidewalls to control the channel. Moreover, for the fabrication of high linearity GaN‐based HEMTs based on the principle of transconductance compensation, the control of threshold voltage is very important. The influence of fin width on the threshold voltage for AlGaN/GaN Fin‐HEMTs with dual‐gate structure is meaningful but until now lack of investigation, which is important for the realization of high linearity devices.…”

Intrinsically Linear Transistor for Millimeter-Wave Low Noise Amplifiers

“…Transistors with vertically stacked multiple quantum well channels were hypothesized to lower g m nonlinearities, , but these were not practically utilized. Innovative material approaches including the use of nitrogen-polar surfaces on gallium nitride (GaN) and source regrowth advanced the linearity figure of merit, the ratio of output third-order intermodulation intercept point (OIP3) to DC power ( P DC ), OIP3/ P DC , to 13.3 dB. − The limited transistor linearity is often addressed with circuit linearization techniques employing derivative superposition (DS) − and cancellation that can extend transistor linearity at low frequencies but become difficult to implement at high frequencies and cannot handle signals with sufficiently large power …”

“…Linear GaN FETs should be capable of resolving transconductance degradation due to an increase in the source resistance ( R s ) at higher V G , known as an increase in the dynamic source access resistance. , At higher gate voltages where carriers transverse the channel with a saturation velocity, the channel current continues to increase by populating more carriers at the channel surface but the ungated source region of the device cannot keep up with required carrier density, and with the saturated carrier velocity, the source resistance increases. This compromise between the channel current and the source resistance has been recently mitigated by introducing Fin-like channels that decrease the channel current and delay the impact of the source resistance on g m roll-off further extending the voltage ranges over which g m is constant. ,,, Notably, Joglekar et al utilized Fins with different widths yet with the same channel width for planar and for each set of Fin widths in a single high electron mobility transistor (HEMT) channel for g m -compensation. However, in that work, the residual currents for each set of previously turned on Fins degrade the overall device current at higher gate voltages and lead to nonlinearities in the current–voltage characteristics.…”

“…This compromise between the channel current and the source resistance has been recently mitigated by introducing Fin-like channels that decrease the channel current and delay the impact of the source resistance on g m roll-off further extending the voltage ranges over which g m is constant. 12,18,27,28 Notably, Joglekar et al 18 utilized Fins with different widths yet with the same channel width for planar and for each set of Fin widths in a single high electron mobility transistor (HEMT) channel for g m -compensation. However, in that work, the residual currents for each set of previously turned on Fins degrade the overall device current at higher gate voltages and lead to nonlinearities in the current−voltage characteristics.…”