In-deep insight into the extrinsic capacitance impact on GaN HEMT modeling at millimeter-wave band

Abstract

The extrinsic input and output capacitances of the field effect transistor small-signal equivalent circuit are typically extracted from the low frequency admittance parameters under ''cold'' pinch-off condition. Despite that, these two capacitances play a significant role also at high frequencies. Intuitively, a first hint of explanation stems from the high frequency reduction of their admittance values connected in parallel to the input and the output of the rest of the equivalent circuit. In particular, the extrinsic capacitances can cause an increase of the real parts of the impedance parameters at high frequencies. This article is aimed at developing an extensive experimental and mathematical analysis based on a comparative study of this behavior for GaN high electron mobility transistor (HEMT) devices up to the millimeter-wave range. The results of this analysis can be applied for estimating the extrinsic capacitances. The main benefit of this modeling technique is that the extrinsic output capacitance can be separated from the intrinsic output capacitance, which can play a significant role especially in case of large devices. V C 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 00:000-000, 2012.

A broadband hybrid GaN cascode low noise amplifier for WiMax applications

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“…Minimizing S 11 requires that Z in = Z 0 . Using simplified HEMT equivalent circuit model, 25 the AC equivalent circuit for the proposed LNA is shown in Figure 2. In this circuit, L is = L 3 ||L 4 and the simplified input impedance Z in can be formulated as: 26…”

GaN HEMT noise modeling based on 50‐Ω noise factor

“…As illustrated in Figure , the tested device exhibits a positive derivative of Re( Z ij ) versus the frequency (PDRZ) under “cold” pinch‐off condition , due to the extrinsic capacitance contributions. Therefore, the extrinsic capacitances have been obtained by increasing their values from zero until the PDRZ effect disappeared from the de‐embedded data, as proposed in . After removing the extrinsic capacitance contributions, the extrinsic resistances and inductances have been obtained from the slopes of the straight lines approximating ω 2 Re( Z ij ) and ω Im( Z ij ) versus ω 2 , respectively (see Fig.…”

“…After removing the extrinsic capacitance contributions, the extrinsic resistances and inductances have been obtained from the slopes of the straight lines approximating ω 2 Re( Z ij ) and ω Im( Z ij ) versus ω 2 , respectively (see Fig. ) . Subsequently, the intrinsic elements have been calculated from the intrinsic admittance ( Y ‐) parameters at the bias point of interest.…”

Direct extraction method for stripline packaged field effect transistor small signal equivalent circuit model

“…The rapid advance in the performance of gallium arsenide (GaAs) field effect transistor's (FET's) highlights the need for the accurate characterization and improvement of packages and mountings suitable for hybrid microwave integrated circuits. The parasitic reactance associated with the package or mounting can seriously limit the performance of a microwave semiconductor device and need to be accurately estimated for good circuit and device modeling [1][2][3][4][5][6][7][8][9]. At high frequencies, the package parasitics affect the transistor.…”