Characterization of the NMOS Transistor for Circuit Simulation

VTO

V_tno, V_tpo

Zero VSB threshold voltage. 24124e49y

KP

Transconductance parameter.

GAMMA

g_n g_p

Threshold voltage parameter.

LAMBDA

l_n l_p

Active-region slope parameter.

Active region transfer characteristic and output characteristic (V_DS > V_effn, V_SB = 0).

Active-region equation solved for V_SG.

Threshold voltage dependence on V_SB.

X variable for V_tn versus X plot in g_n determination.

LabVIEW Computations

Components

Procedure

Set RS value. Run NMOSparsub.vi and adjust VSSinit for a minimum ID mA. Test run NMOSparsub.vi with VDS = 3 V and 10 V. Execution halts at ID mA. The VI runs as a subVI in the next part. Default and save. Saved VSSinit is used in the Top VI in the next part.

Components

LabVIEW Computations

Procedure

Set RS. Run NMOSparam.vi to obtain a set of NMOS parameters. The VI runs NMOSparsub.vi automatically with VDS = 3 V and VDS = 10 V. The sweep stops at ID mA or |Chan0_out| = 10 V. Default and save the VI.

Components

Note: V_GS will be larger with the body effect.

Procedure

Note that PMOS body pin 14 and the NMOS drain terminal are at ground. Set RS and VSSinit from NMOSparsub.vi. Run NMOSgamsub.vi with VSB = 0 V and 3 V to verity that circuit is functioning properly. Note the change in the VGS range for the larger VSB. VSSinit is adjusted automatically for larger values of VSB, to obtain, approximately, a starting ID of about 50 mA. Default and save the Front Panel to save VSSinit.

Components

LabVIEW Computations

Procedure

Set RS. With NMOSgamsub.vi open, run NMOSgamma.vi to obtain Gamma. Adjust 2fF to try to match Vtno (intercept, curve fit) with Vtno (VSB = 0, transfer characteristic, graph on right). Save the results.

Components

Use RS from NMOSgamma.vi.

Procedure

Set RS. Install SPICE parameters from NMOSparam.vi and NMOSgamma.vi. Run NMOS_Cir.vi to obtain ID versus VGS with a sweep of VSS. The iteration solution obtained in SPICEgamma.vi (Diagram below) is compared in the graph of NMOS_Cir.vi. Adjust VSSinit to obtain IDmin of about 50mA. Re-adjust Gamma for best fit. Then save a data file with your data file name. The data file must be in the folder with the Mathcad file. The file name must have a *.prn extension.

A file can be obtained from the graph of the defaulted and saved VI using XY1toDataFile.vi. The VI XY1toDataFile.vi is located in \\LabVIEW 6\User.lib\Dat_Files\Dat.llb.

Note that XY1toDataFile.vi is different from XYtoDataFile2.vi, as used to obtain a data file in the Diagram of NMOS_Cir.vi. The Control Graph of XYtoDataFile2.vi accepts single plots while XY1toDataFile.vi is for graphs with two Y functions (with only one Y function in the data file). For convenience, a copy of XY1toDataFile.vi, GetDataFile.vi, is included in the Project04.llb. For clarification, XY1Y2toDataFile.vi accepts graph data with two Y functions and includes both in the data file.