Keithley 2657A - Page 138

Section 3: Functions and features Model 2657A High Power System SourceMeter® Instrument Reference Manual
3-24 2657A-901-01 Rev. B/December 2012
Solving for k and b provides the following formulas:
Where:
V
end
= The source value at the end point
V
start
= The source value at the start point
N
= The number of points in the sweep
A
= The asymptote value
The number of points in a sweep is one greater than the number of steps in the sweep.
The following figure is an example of a five-point logarithmic sweep from 100 V to 1000 V.
Figure 36: Logarithmic staircase sweep (100 V to 1000 V, five steps)
( )
log10(V
end
- A) - log10(V
start
- A)
N-1
k = V
start
- A
b = 10
NOTE
Delay
Delay
Delay
Delay
Stop
(1000)
Measure
#1
Measure
#2
Measure
#3
Measure
#5
X = Measurement point
X
X
X
X
Delay
X
Measure
#4
100
1000
562.34
316.23
177.83
Log
scale
Start
Log points = 5
Volts