FOCUS MICROWAVES GROUP

Focus Compact Modeling

The intuitive advanced compact model

V01/19powered by FOCUS MICROWAVESIntroduction
The Focus Compact Model (FCM) utility is a streamlined
software package designed to be used with Focus’ AURIGA
high-end pulse system, that is used to generate Compact
Models for transistors from their Pulsed-IV and wideband
pulsed s-parameter data.

Pulsed IV & S-Parameter Meas. Setup

This is achieved by generating a network of lumped circuit
elements that represent accurately the fundamental linear& non-linear behaviour of the device over a broad range ofbias and power range.
The result of the modelling is a netlist and compatible withthe most common CAD tools used in RF Design such as
AWR Microwave office (MWO) and Keysight Advanced Design Studio (ADS).
Key features of the FCM:
Linear and Non-Linear Compact Transistor Model Extractionof III-V materials (GaN HEMT or similar model).
High frequency FET model parameters from a combinationof DC and S-parameter measurements.
Gate-lag and drain-lag trapping.
Basic thermal model extraction.
Linear Model:
8 Extrinsic parameters (RG, RD, RS, LG, LD, LS, CPG, CPD )8 Bias dependent Intrinsic parameters (RGD, Ri, CGS, CGD,CDS, GM, RDS, & Γ)
Non-Linear Model:
NL Capacitances CGS & CGD
NL Current Sources IDS
NL Diodes DGS & DGD
Export Capability to ADS and MWO.

Simulation2

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Measurements

Equivalent Circuit HemTThe purpose of electrical representation or equivalent circuit of HEMT or any transistor in the form of lumped circuit
elements is to implement and simulate its static and RF behaviour in CAD tools. This technique is particularly usefuland often directly correlated to physical entities within thedevice structure, as illustrated below.

AlGaN/GaN HEMT transistor

This is divided into two parts:i) The Intrinsic part where the region under the gate (modulation occurs here) represented with a set of 8 intrinsic elements (RGD, Ri, CGS, CGD, CDS, GM, RDS, Γ).
ii) The Extrinsic part represented with a set of 8 extrinsic
elements (RG, RD, RS, LG, LD, LS, CPG, CPD). These elements need to be extracted for small signal model implementation. The extraction process will be discussed in thefollowing section.

Keysight ADS Data Display

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3Extraction & Example
Linear Elements Extraction

EDA Example

The linear model extraction is a crucial step as this will be
the basis for the non-linear model development.

The Focus Compact Model portfolio is fully supported in all
major EDS tools including AWR Microwave office and Keysight Advanced Design System.

i) From a set of initial extrinsic values, de-embedding ofS-parameters is done at the intrinsic reference plane of thetransistor.
ii) Using these intrinsic S-parameter measurements, an explicit calculation of the intrinsic elements is achieved foreach frequency. These intrinsic parameters need to be independent of frequency and this condition is checked during
the optimization process.
iii) If the intrinsic elements depend on the frequency, a new
set of extrinsic elements are provided.
iv) An optimization algorithm is used in a loop to generate
iterative steps for the extrinsic parameters that give a correct
set of extrinsic elements. These elements are independentof bias.

Optimisation Process

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