Rcsat - Keithley S530 User Manual

Section 3: Test subroutine library reference

rcsat

This subroutine estimates the collector resistance (R
current (I ) are swept at a constant beta ().
B
Usage
double rcsat(int e, int b, int c, int sub, double ice1, double ice2, double beta,
double vsub, int npts, double *r, int *iflag)
e
b
c
sub
ice1
ice2
beta
vsub
npts
r
iflag
Returns
Details
This subroutine estimates the modeling parameter RC in the saturation region of a transistor using
Getreu's method (Ian Getreu, Modeling the Bipolar Transistor, Tektronix, 1976). Current is stepped
into the base and collector at a specified  (normally 10). The developed collector-emitter voltage
(V ) is measured. V
CE
linear least-squares (LLSQ) line is fit to the data. The inverse of the slope of this line gives R
device is in the common-emitter configuration.
For high-speed or microwave bipolar devices, best results are obtained by starting at the maximum
current and sweeping the current to a lower value.
An incorrect value of  can result in a large excursion of V
Because of this, the collector voltage is limited to 16 V.
To measure R
smaller than actual value for  (overdriving the base).
3-50
Input The emitter pin of the device
Input The base pin of the device
Input The collector pin of the device
Input The substrate pin of the device
Input
The start of the collector-emitter current (I
Input
The end of the I
Input
The current ratio, I
Input The forced substrate bias, in volts
Input The number of points in the sweep
Output The correlation coefficient
Output The status flag:

0 = Normal completion

1 = Insufficient points for LLSQ analysis

2 = Calculated LLSQ slope is 0.0
Output The collector resistance modeling parameter
and I data is extracted from the positive slope portion of the curve, and a
CE CE
correctly, make sure the transistor is saturated. You can do this by entering a
C SAT
S530 Parametric Test System Test Subroutine Library User's Manual
) modeling parameter when collector current (I
C
sweep, in amperes
CE
/I
C B
, which may break down the device.
CE
) and base
C
) sweep, in amperes
CE
S530-907-01 Rev. A / September 2015
. The
CSAT