Nonlinear Steady-State III–V FET Model for Microwave Antenna Switch Applications

et al. 2018

It has been found that the analytical extraction methods cannot be applied to the usual test structure of the switch high electron-mobility transistor (HEMT) with a large-value gate grounded resistor. The significant effect of the precise multicapacitive current path on switch model precision has also been found. The multicapacitive current path here is different from the seemingly similar hypothesis proposed for the distributed parasitic effects at high frequencies (eg, D-band). In fact, for switch based HEMT, it is important to distinguish between the capacitive current paths accurately even at relatively low frequencies. Due to the existing of the large gate resistance, the usual capacitance mix decreases the accuracy of the switch model significantly. Thus an analytical method has been developed to calculate parasitic capacitances (the capacitance to ground and the interelectrode capacitance) through full-wave electromagnetic analysis. For practical applications and further verification, the whole HEMT switch small-signal models and the direct extraction methods are presented. The simulated results fit well with the measurements up to 40 GHz. K E Y W O R D S electromagnetic analysis, high electron-mobility transistor, interelectrode parasitic capacitance, microwave switches, small-signal model 1 | INTRODUCTION In 1988, Dambrine et al.proposed an analytical way to extract FET small-signal equivalent circuit parameters. 1 All the parasitic parameters were analytically extracted by using cold-FET method. After de-embedding all the parasitic effects from the whole S parameters, the intrinsic parameters were calculated by analytical equations. 2 De-embedding methods, cold-FET techniques, and analytical equations 3 are used by lots of FET small-signal model extraction methods today. Note that Reference 1 also has some limitations, for example, the pinch-off intrinsic model used to determine the parasitic capacitance parameters tends to overestimate the value of the drain to ground capacitance (C pd ). The high positive gate bias condition used to determine the parasitic inductances and resistances have the potential to destroy the gate Schottky diode. 4 In addition, for high electron-mobility transistors (HEMTs), it is difficult to apply enough high gate bias to ignore the gate capacitance effect. 5,6 Many works are making improvements to meet the needs of new semiconductor technologies and new applications like high frequency applications. 7-11 The small-signal modeling is also the basis of the large-signal and noise modeling. [12][13][14] As stated above, lots of articles and effort has been dedicated to common-source FET small-signal modeling, but high-frequency switch FET small-signal modeling is still difficult. Very few works concern switch FET small-signal modeling. [15][16][17][18][19][20][21] Numerical solutions concern intrinsic effects only and are difficult to meet measured behavior. [15][16][17] The simplified equivalent circuits cannot capture full feature of the switch HEMT at high frequencies. 18,19...

Section: Introductionmentioning

confidence: 99%

Direct extraction method of HEMT switch small‐signal model with multiparasitic capacitive current path

et al. 2018

“…The single‐gate and dual‐gate switch‐HEMTs share the same intrinsic parameters since they share the same gate process. R ig is the inter‐gate parasitic resistance . R G represents the large gate‐resistor, which was modeled by a simple R‐C parallel network .…”

Section: Complete Parasitic Capacitance Shell Extractionmentioning

confidence: 99%

“…The extracted intrinsic model of the single‐gate HEMT is directly embedded into the parasitic shell of the dual‐gate HEMT. The inter‐gate parasitic‐resistance R ig is fitted with the on‐state channel‐resistance . By modeling several 4‐finger GaAs HEMTs with different gate‐widths ( W g ), linear scalability of the models are found, Figures and illustrate the scalability of the capacitances of single‐gate and dual‐gate model, respectively.…”

Section: Switch Small Signal Model Verificationsmentioning

confidence: 99%

“…However, the distributed model is too complicated, and the scalability of the model is difficult to get. Several papers concerning switch‐HEMT large‐signal modeling not only provide solutions to switch‐HEMT model at microwave low frequencies (L‐band), but also raise some special modeling requirements of the intrinsic model of switch‐HEMT . Since capacitances are almost the only parameters of off‐state switch model, these papers draw much attention to capacitance modeling.…”

Section: Introductionmentioning

confidence: 99%

“…Since capacitances are almost the only parameters of off‐state switch model, these papers draw much attention to capacitance modeling. For example, the effect of charge‐trapping on intrinsic‐capacitance was found very important to harmonic simulations . In Reference , symmetrical large‐signal intrinsic‐capacitance model was studied in detail.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Complete parasitic‐capacitance‐shell extraction of high‐frequency switch‐HEMT equivalent‐circuit model

Hu²,

2020

This paper presents a new solution to a particular problem of high electron‐mobility transistor (HEMT) equivalent‐circuit modeling, that is, complete parasitic‐capacitance‐shell extraction of high‐frequency single‐gate and dual‐gate switch‐based HEMTs, which is very important to the accuracy of high‐frequency HEMT switch models, but not important in the conventional common‐source HEMT modeling for amplifier‐applications. A full‐wave electromagnetic (EM) analysis based method is proposed to analytically extract the complete parasitic‐capacitance‐shell of single‐gate and dual‐gate switch‐based HEMTs. All the 6 parasitic capacitances of the single‐gate switch‐based HEMT and all the 10 parasitic capacitances of the dual‐gate switch‐based HEMT are extracted by linear equations. No resistance parameter is needed to calculate the capacitance‐to‐ground and the interelectrode‐capacitance, and for the first time, all the 10 parasitic capacitances of the dual‐gate switch‐based HEMT are completely considered and analytically extracted. Then, a consistent and systematic modeling procedure of single‐gate and dual‐gate switch‐based HEMT is verified. With the complete parasitic‐capacitance‐shells extracted, the accurate intrinsic model of the single‐gate HEMT can be directly embedded into the parasitic‐shell of the dual‐gate HEMT. The predicted scattering parameters of the single‐gate and dual‐gate series switches fit well with the measurements up to 40 GHz, and accurate linear scalability are also found.

A HEMT large‐signal model for use in the design of microwave switching circuits

2019

The nonlinear sources of switch-HEMTs have been well analyzed by using the measured data. The small signal intrinsic capacitances (under both positive and negative V ds operation) have been extracted by an extended small signal model. one-dimension capacitance model has been effectively applied to model the small signal incremental capacitances directly extracted from the key operation region, which has also automatically taken into account the surface trapping effects. A new capacitance model has been effectively proposed to well fit the key nonlinear source (the deep subthreshold capacitance) of switch-HEMTs. Simple switching function and additional voltage dependence have been applied to model the wide linear-region (from high-V gs region to deep subthreshold region) of channel current. On/off state small signal insertion loss, small signal isolation, weak harmonics, and power carrying capabilities are accurately predicted by the large signal model. The model shows very good convergence of circuit simulation. Meanwhile, the simple equations and distinguishing among the capacitances accurately make the scaling rules simple and accurate. K E Y W O R D Sharmonic, high electron-mobility transistor (HEMT) switch, large signal model, microwave switch, monolithic microwave integrated circuit (MMIC), small signal model