Keithley 6220 User Manual

5-52 Delta, Pulse Delta, and Differential Conductance Model 6220/6221 Reference Manual
Return to Section 5 topics
Figure 5-14
Differential Conductance measurement process
10µA
[(A-B)/2] + [(C-B)/2]
2
Start
Stop
Step
dV #1
(-1)
0
= 
·
Step
Step
Step
Step
Step
dV Calc
#1
dV Calc
#4
Start = 0µA
Step = 10µA
Stop = 50µA
Delta (dI) = 20µA
[(B-C)/2] + [(D-C)/2]
2
dV #2
(-1)
1
= 
·
[(C-D)/2] + [(E-D)/2]
2
dV #3
(-1)
2
= 
·
[(D-E)/2] + [(F-E)/2]
2
dV #4
(-1)
3
= 
·
[(E-F)/2] + [(G-F)/2]
2
dV #5
(-1)
4
= 
·
[(F-G)/2] + [(H-G)/2]
2
dV #6
(-1)
5
= 
·
= Sweep with 20µA Delta (dI)
= Sweep with 0µA Delta (dI)
time
0µA
20µA
30µA
40µA
50µA
60µA
70µA
-10µA
Step
Delta
Delta
Delta
Delta
Delta
Delta
Delta
Delta
dV Calc
#3
dV Calc
#5
dV Calc
#2
dV Calc
#6
-20µA
dV Calc #2 B to D
dV Calc #3 C to E
dV Calc #4 D to F
dV Calc #5 E to G
dV Calc #6 F to H
dV Calc #1 A to C
dV Calculations  The following equations are used by the 622x to calculate differential voltage (dV).
To calculate dV, points A through H are 2182/2182A voltage measurements (A/D readings).
A/D Rdg
A
A/D Rdg C
A/D Rdg E
A/D Rdg H
A/D Rdg F
A/D Rdg D
A/D Rdg = 2182/2182A voltage measurement conversion.
dG and dR Calculations  With dI known (dI = Delta) and dV calculated, the 622x can then calculate
differential conductance (dG) or differential resistance (dR).
With G units selected, readings are calculated as follows: dG = dI/dV.
With R units selected, readings are calculated as follows: dR = dV/dI.
dV Calc = Calculate differential voltage (dV) using
last three A/D Rdgs.
A/D Rdg G
A/D Rdg B
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Keithley 6220 Specifications

General

Brand	Keithley
Model	6220
Category	Measuring Instruments
Language	English