Comparative Investigation of Single and Double Channel AlGaN/GaN HEMTs for LNAs

This work presents a detailed comparative study of LNA, designed using Double Channel (DC) HEMTs and Single Channel (SC) HEMTs. The dc characteristics of both the HEMT structures were calibrated with published simulated models, using Silvaco Atlas TCAD and Keysight ADS. The structures have been compared in terms of dc characteristics, as well as frequency performance, which were further implemented in Keysight ADS software. In DC HEMT, as two channels are acting in parallel, a peak in noise parameter could be observed when the upper channel starts conducting (i.e. moving from off to on state) which further corresponds to the kink in the Gm curve of the DC HEMT. A lower value of \(G_{m}^{^{\prime\prime}}\) and higher value of VIP3 for DC HEMT compared to SC HEMT results in lower IMD3 for DC HEMT, implying more linearity. For SC HEMT, operating in X-band, the amount of amplification decreases with operating frequency, thus inhibiting its usage for wideband applications. However, marginal reduction in a steady gain (about 13.6 dB) has been observed from DC HEMT. The minimum noise reported for DC HEMT-based LNA is 0.306 dB at 8 GHz operating frequency, compared to 0.348 dB for SC HEMT-based LNA. Thus, due to steady gain across the X-band of microwave frequencies, the LNA circuit with DC HEMT can be a suitable candidate for multimode trans-receivers, RADAR applications, and terrestrial and space communications.