Analytical method for determining equivalent circuit parameters of GaAs FETs

Abstract

An analytical method has been developed that gives a simple and practical means of extracting small-signal equivalent circuit parameters (ECP's) of GaAs FET's with negligibly small bond-pad capacitances. Only the S-parameter measurement of the pinched-off cold field-effect transistor (FET) is enough to determine the extrinsic FET ECP's. The intrinsic FET ECP's of a medium-power Ku-band GaAs FET chip with a total gate width of 800 Irm have been analytically extracted for two types of eight-element intrinsic FET models; Model 1 (Curtice model) andModel 2 that differ in the control voltage (li:) definition. Model 2 with 17, defined across the gate-source capacitance is found more appropriate judging from the smaller frequency dependence of the ECP's and a better agreement between the calculated and measured S-parameters over 2-20 GHz.

On wafer‐scaled GaAs HEMTs: Direct and robust small signal modeling up to 50 GHz

“…The extrinsic circuit elements are obtained from S-parameter measurements under "cold" pinch-off condition (i.e., V ds ϭ 0 V and V gs ϭ Ϫ1.275 V) [5][6][7][8]. Under this particular bias condition, the intrinsic equivalent circuit can be simplified in a capacitive ⌸ network consisting of C gs , C gd , and C ds .…”

“…Although nowadays GaN-based HEMTs are attracting huge attention, thanks especially to their superior power performance, GaAs HEMTs allow to obtain noise performance which are still difficult to improve significantly. The objective of this article is to investigate the small signal modeling of scaled AlGaAs/GaAs HEMTs, because the modeling of the microwave small signal behavior of the active solid-state devices is still a key issue [3][4][5][6][7][8][9]. This is because an accurate multibias small signal model is essential for evaluating the transistor microwave performance, for designing both power and low noise amplifiers, and for building a reliable large signal model.…”

An improved intrinsic small‐signal equivalent circuit model of delta‐doped AlGaAs/InGaAs/GaAs HEMT for microwave frequency applications

“…Fast and accurate parameter extraction for HEMT modelling is hence needed in order to design, develop, and produce high-yield, lowcost, high performance monolithic circuits. Various methods have been reported for extracting equivalent circuit parameters using numerical optimization [1][2][3][4] or analytical methods [5][6][7][8][9]. The numerical optimization method results in a set of component values that depend on the initial values and at times resulting values may differ considerably from their physical values, while the analytical method allows us to extract the equivalent circuit parameter in a straightforward manner.…”

On the small signal modeling of advanced microwave FETs: A comparative study

“…The advantage of using a forward bias condition for determining these parasitic ECPs is that under this bias condition the influence of the intrinsic RC parallel networks becomes less and, as a consequence, the parasitic ECP extraction resolution increases. However, the inductances and resistances can be respectively determined also from the real and imaginary parts of the Z-parameters of the resistive capacitive inductive T network representing the device at high frequencies under pinch-off condition [2,[11][12][13]. As it will be shown in the following section, we have used measurements at V gs far and close to the pinch-off for extracting the parasitic resistances in the case of GaAs HEMT.…”