Equivalent‐circuit–based modeling of the scattering and noise parameters for multi‐finger GaAs pHEMTs

Abstract

This study is focused on the experimental characterization of the highfrequency linear behavior of interdigitated gallium arsenide (GaAs) pseudomorphic high-electron-mobility transistors (pHEMTs) in terms of scattering and noise parameters. A measurement-based model is developed by using the equivalent-circuit representation. The values of the extrinsic bias-independent elements are obtained by means of the "cold" approach and then subtracted from the scattering parameter measurements at the bias point of interest, thereby enabling calculation of the intrinsic bias-dependent elements. Next, the extracted small-signal equivalent circuit is expanded by assigning an equivalent noise temperature to each resistor, thus obtaining the noise model.The validity of the extracted equivalent-based model is fully confirmed by the good agreement between measurements and model simulations over a broad frequency range for devices having different number of gate fingers. In addition, the scaling of the achieved performance versus the total gate width is analyzed and discussed. FIGURE 1 Photo of the studied GaAs pHEMTs with different gate width: A, 2 × 50 μm; B, 4 × 50 μm; C, 6 × 50 μm; and D, 8 × 50 μm 2 of 7 CADDEMI ET AL. 2 of 7 CADDEMI ET AL. FIGURE 5 Measured (red lines) and simulated (blue lines) S-parameters from 0.1 to 50 GHz at V DS = 2 V and I D = 200 mA/mm for two GaAs pHEMTs with different gate width: (A, B) 2 × 50 μm and (C, D) 8 × 50 μm. The maximum radius for the two polar plots is 15 FIGURE 4 Measured S-parameters from 0.1 to 50 GHz at V DS = 2 V and I D = 200 mA/mm for four GaAs pHEMTs with different gate width: (blue lines) 2 × 50 μm, (red lines) 4 × 50 μm, (green lines) 6 × 50 μm, and (purple lines) 8 × 50 μm. The maximum radius for the polar plot is 15 4 of 7 CADDEMI ET AL. 4 of 7 CADDEMI ET AL.

MINLP‐based hybrid strategy for operating mode selection of TES‐backed‐up refrigeration systems

“…46 The BONMIN uses the Interior Point OPTimizer (IPOPT) for solving relaxed problems and Coin-OR Branch and Cut (CBC) as the mixed-integer solver. 47,48 The optimal operating mode scheduling given by the mixed-integer nonlinear optimization is represented in Figure 8, computed from the binary variable set { e,sec , TES , TES,sec } defining whether the corresponding cooling power is active or not, according to Section 2.3.…”

Dual-Conversion Microwave Down Converter for Nanosatellite Electronic Warfare Systems

“…As a consequence, it was not possible to simulate the noise behavior of the system, which was instead analytically estimated. In detail, the noise factor, 𝐹 𝑐𝑎𝑠 , of all the cascaded components in the path from the signal input up to the IF was computed by using the wellknown Friis formula [24,[26][27][28][29]. (1) where 𝐹 𝐿𝑁𝐴 , 𝐹 𝑀𝐼𝑋 , 𝐹 𝐴𝑀𝑃𝐿 , 𝐹 𝐹𝐼𝐿𝑇1 and 𝐹 𝐹𝐼𝐿𝑇2 are the noise factors of the CMD240C4 LNA, MM1-1467H mixer, AMM-6702 amplifier, PB1182WB filter and VLF-1500+ filter, respectively, whereas 𝐺 𝐿𝑁𝐴 , 𝐺 𝑀𝐼𝑋 , 𝐺 𝐴𝑀𝑃𝐿 𝑎𝑛𝑑 𝐺 𝐹𝐼𝐿𝑇1 are the related gains.…”

Measurement‐based analysis of GaAs HEMT technologies: Multilayer D‐H pseudomorphic HEMT versus conventional S‐H HEMT

“…These DUTs were experimentally investigated in order to access their capability for microwave applications. The importance of this crucial task can be seen in the fact that, over the years, many studies have been focused on the characterization of DC, 23‐26 small‐signal, 25‐31 and nonlinear characteristics 32‐37 of the GaAs HEMT technology. The DC output characteristics of the DUTs have been modeled using the well‐known FET's Curtice model 38,39 .…”