BOOK_CONTENT
From Introduction to Modeling HBTs

6.1 THE SPICE GUMMEL-POON MODEL

The SPICE Gummel-Poon (SGP) model was for a very long time de facto the standard bipolar model. It was introduced by Gummel and Poon [4, 5], and is described in various textbooks [6, 7]. It is available in virtually every circuit simulator, and modern models can be understood as either extensions or refinements of it. It includes the following effects and features:

  • Early effect;

  • Webster effect;

  • Excess transit time due to base pushout;

  • Partition of the base-collector capacitance into intrinsic and extrinsic part;

  • Temperature scaling (impact of ambient temperature on electrical performance).

Since it does not account for dynamic self-heating and collector-charge dependence on current, its capability to describe HBTs is rather limited.

The equivalent circuit of the Gummel-Poon model is shown in Figure 6.1 and its parameters are listed in Table 6.1.

Table 6.1: SGP Model Parameters

Parameter

Meaning

Units

Ideal DC Parameters

Is

transport saturation current

A

Bf

ideal forward current gain

Nf

forward emission coefficient

Br

ideal reverse current gain

Mr

reverse emission coefficient

Parameters of Base Charge q b

Vaf

forward Early voltage

V

Var

reverse Early voltage

V

Ikf

forward base high-current injection

A

Ikr

reverse base high-current injection

A

Nonideal Base Currents

Ise

BE leakage saturation current

A

Ne

BE leakage emission coefficient

Isc

BC leakage saturation current

A

Nc

BC leakage emission coefficient

Depletion Capacitances

Cje

BE zero-bias capacitance

F

Vje

BE diffusion voltage

Copyright Artech House, Inc. 2006 under license agreement with Books24x7

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Topics of Interest

6.2 THE VBIC MODEL This model is the result of the joint efforts of various semiconductor and EDA companies to develop a new industry standard model for silicon bipolar transistors as a replacement...

6.5 THE FBH HBT MODEL The FBH Model [18] was developed by the author at the Ferdinand-Braun-Institut fur H chstfrequenztechnik, in Berlin, Germany. Its primarily goal was to facilitate the design of...

REFERENCES [1] L.H. Camnitz, S. Kofol, T. Low, and S.R. Bahl, "An Accurate, Large Signal, High Frequency Model for GaAs HBTs," Dig. GaAs IC Symp., 1996, pp. 303 306. [2] Philips Semiconductor,...

A complete and rigorous description of biasing techniques, including all temperature and leakage effects, for bipolar, JFET, dual-gate FET, and hybrid devices, is beyond the scope of this chapter.

6.4 THE AGILENT HBT MODEL The Agilent model [15, 16] has similar roots as the UCSD model, as it is based on L. Camnitz' model [1]. It was developed at Agilent Technologies in order to overcome the...