Sites:
Home > Technical Library

6.1: THE SPICE GUMMEL-POON MODEL

By Matthias Rudolph
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
Products & Services
Bipolar RF Transistors
Bipolar RF transistors consist of an N-type or P-type layer sandwiched between two layers of the opposite type. They are designed to handle high-power radio frequency (RF) signals in devices such as stereo amplifiers, radio transmitters, and television monitors.
General Purpose Diodes
General-purpose diodes are electric components that conduct electric current in only one direction, functioning similarly to a one-way valve.
High Voltage Diodes
High voltage diodes are designed for use in high-voltage applications.
Rectifiers
Rectifier diodes are designed for use in rectification circuits. Rectifiers are used to convert AC to DC.
Varactor Diodes
Varactor diodes are p-n junction diodes that are designed to act as a voltage controlled capacitance when operated under reverse bias.
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]...

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...