NMOS Parameter Extraction
The NMOS Parameter Extraction is composed of two experiments, the NMOS Id-Vd characteristics and the NMOS Id-Vg characteristics. Afterwards, the parameters are extracted using the experimental data. The NMOS Id-Vd characteristics are measured by applying a staircase sweep voltage to the drain (Vd) of the NMOS and monitoring the drain current. A constant voltage is applied to the gate (Vg) during each sweep, and a group of Id-Vd data curves can be acquired by varying the gate voltage between sweeps. The NMOS Id-Vg characteristics are measured by applying staircase sweep voltage to the gate (Vg) of the NMOS and monitoring the drain current. A constant voltage is applied to the drain (Vd) during each sweep, and a group of Id-Vd data curves can be acquired by varying the gate voltage between sweeps. A bias voltage can also be applied to the substrate contact,(Vb) but to get better extraction results, it is recommend that the bias voltages be set to zero, or at least remain the same in both experiments. The source is grounded in both experiments.(Fig.10)
The experimental parameters are entered using two Source Setup pop-up panels, one for each of the two experiments. The Id-Vd experimental parameters include the start, stop, and step voltages for the sweep, the start voltage, step voltage and the number of steps for the group of gate voltages, as well as the bias voltage for the substrate. You may also select the compliance current for protection. Both the drain voltage and gate voltage are limited to (-5.0V, 5.0V), and the substrate bias is limited to (-0.3V, 3.0V). When this selection is done, you may click the button "Next Source Setup Panel", which will lead to the Source Setup panel for the Id-Vg characteristics experiment. Set the parameters similarly as described above. The drain voltage and gate voltages are limited to (-5.0V, 5.0V), and the substrate bias is limited to (-0.3V, 3.0V).
The server will treat this as two experiments, and will send the results back consecutively. The client page will then use the data from the two experiments to extract the device parameters. The parameters are extracted by a program similar to the beta-version of the AIM-Spice. These are parameters of the AIM-Spice MOS model, Level 7,which is described in detail in the AIM-Spice online reference manual and also in the following book:
T. A. FJELDLY, T. YTTERDAL and M. S. SHUR, "Introduction to Device Modeling and Circuit Simulation", John Wiley & Sons, New York (1998), ISBN 0-471-15778-3.
The extracted parameters include:
VTO--the threshold voltage
ETA--the subthreshold slope
UO--the Surface mobility
LAMBDA--the output parameter
M--the knee parameter
Other model parameters can be divided into two groups:
1. The gate width and gate length must be specified by the manufacturer. For this device,
Device width=25
mmDevice length=2 mm
2. Other parameters that might have default values specified in the AIM-Spice online reference manual
The NMOSFET under test is one of the devices integrated on a chip named
AIM-Spice Test Chip.To run the experiment, go back to
Remote Lab Homepage.