# New RF MOSFET Small Signal SPICE Model Part 2

Ickjin Kwon, Minkyu Je, Kwyro Lee, and Hyungcheol Shin Department of Electrical Engineering, Korea Advanced Institute of Science and Technology

Parameter Extraction Procedure

RF MOSFET Small - Signal Model
and Parameters

Small-signal equivalent circuit of MOSFET after de-embedding parasitics
is shown in Figure 1 and small-signal model parameters are listed in Table
1.

Figure 1. Common-source equivalent circuit of a

MOSFET after de-embedding parasitics of

on-wafer pads and interconnection lines.

Parameter Extraction Strategy

Parameter extraction is performed from real and imaginary parts of the
Y-parameters. Each parameter is extracted from the Y-parameter equations
which contain frequency terms.

To fit a straight line to the data plot, linear regression is used.

With the X data, the independent variable, and the Y data, the dependent variable, the estimated linear regression model is stated;

where the parameters, A and B, are estimated by the method of least squares.

A is the intercept :

B is the slope :

The standard deviation is defined as Where (Xi,Yi) are the data points,

N is the number of data points,

Parameters such as *C _{gd}, C_{gs},
R_{g}, C_{dg}, C_{jd}, *and

*C*are extracted as a function of frequency and in these cases the extracted values are determined by their mean value. The mean of parameter is calculated by

_{ds}where Pi are the extracted parameter values as a function of frequency.

Extraction Routine

* Note that, w = 2 <-> <-> .

**Step 1. **

*g _{m}* is obtained from y-intercept of
Re[

*Y*] versus .

_{21}

Figure 2. Extraction results of gm.

**Step2. **

*g _{ds}* is obtained from y-intercept
of Re[

*Y*] versus .

_{22}

Figure 3. Extraction results of *gds*.

**Step 3. **

* Extracted *Cgd* is the mean value
as a function of frequency.

Figure 4. Extraction results of *Cgd*.

**Step 4. **

* Extracted *C _{gs}* is the
mean value as a function of frequency.

Figure 5. Extraction results of *Cgs*.

**Step 5.**

* Extracted Rg is the mean value as a function of frequency.

Figure 6. Extraction results of *Rg*.

**Step 6. **

* Extracted Cdg is the mean value as a function of frequency.

Figure 7. Extraction results of Cdg.

**Step 6. **

* Extracted Cdg is the mean value as a function of frequency. Step 7. Rsubd and Cjd are obtained from linear regression using the following relation.

*R _{subd}* is determined from
slope of

*Y*as a function of .

Figure 8. Extraction results of Rsubd.

**Step 8. **

* Extracted *C _{jd}* is the
mean value as a function of frequency.

Figure 9. Extraction results of *Cjd*.

**Step 9. **

* Extracted *C _{ds}* is the
mean value as a function of frequency

Figure 10. Extraction results of *Cds*.