Keithley 2651A Reference Manual page 131

Section 3: Functions and features
Solving for k and b provides the following formulas:
Where:
= The source value at the end point
V
end
= The source value at the start point
V
start
= The number of points in the sweep
N
= The asymptote value
A
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 1 V to 10 V.
Volts
3-24
Model 2651A High Power System SourceMeter® Instrument Reference Manual
k = V - A
start
(
log10(V
b = 10
Figure 38: Logarithmic staircase sweep (1V to 10V, five steps)
Log
scale
10
5.6234
3.1623
Delay
1.7783
Delay
1
X
Start
Measure
#1
)
- A) - log10(V - A)
end start
N-1
NOTE
Delay
Delay
X
Log points = 5
X
Measure Measure
#2 #3
X = Measurement point
Delay
X
Stop
(10)
X
Measure
Measure
#4 #5
2651A-901-01 Rev. A / March 2011