Keithley Series 2600 User Manual

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3-4

SECTION 3

Bipolar Transistor Tests

measures I

. SMUA sets V

to the desired ﬁxed value, and it also

measures I

Due to the low current measurements associated with this type of

testing, the Keithley Model 2636 System SourceMeter instrument

is recommended. Its low level current measurement capabilities

and dual-channel conﬁguration are ideal for producing high

quality Gummel plots of transistors.

3.4.2 Measurement Considerations

As written, the range of V

test values is from 0V to 0.7V in 0.01V

increments. It may be necessary, however, to change these limits

for best results with your particular device. Low currents will be

measured so take the usual low current precautions.

3.4.3 Example Program 5: Gummel Plot

Program 5 demonstrates the basic programming techniques

for generating a Gummel plot. Follow these steps to run this

program:

With the power off, connect a dual-channel System Source-1.

Meter instrument to the computer’s IEEE-488 interface.

Connect the test ﬁxture to both units using appropriate 2.

c a b l e s .

Turn on the instrument and allow the unit to warm up for two 3.

hours for rated accuracy.

Turn on the computer and start Test Script Builder (TSB). Once 4.

the program has started, open a session by connecting to the

instrument. For details on how to use TSB, see the Series 2600

Reference Manual.

You can simply copy and paste the code from Appendix A in 5.

this guide into the TSB script editing window (Program 5),

manually enter the code from the appendix, or import the TSP

ﬁle ‘Gummel.tsp’ after downloading it to your PC.

If your computer is currently connected to the Internet, you

can click on this link to begin downloading: http://www.

keithley.com/data?asset=50918

Install an NPN transistor such as a 2N5089 in the appropriate 6.

transistor socket of the test ﬁxture.

Now, we must send the code to the instrument. The simplest 7.

method is to right-click in the open script window of TSB,

and select ‘Run as TSP ﬁle’. This will compile the code and

place it in the volatile run-time memory of the instrument.

To store the program in non-volatile memory, see the “TSP

Programming Fundamentals” section of the Series 2600 Refer-

ence Manual.

Once the code has been placed in the instrument run-time 8.

memory, we can run it at any time simply by calling the

function ‘Gummel()’. This can be done by typing the text

‘

G u m m e l()

’ after the active prompt in the Instrument Con-

sole line of TSB.

In the program ‘Gummel.tsp’, the function 9.

Gummel

(vbestart, vbestop, vbesteps, vcebias)

created.

vbestart

• represents the sweep start voltage value on

the base of the transistor

vbestop

• represents the sweep stop value

vbesteps

• is the number of steps in the base

voltage sweep

Series 2600

System

SourceMeter

Channel A

Source V

Measure I

Series 2600

System

SourceMeter

Channel B

Sweep V

Measure I

Test

Fixture

Transistor

Under Test

Output HI

Output LO

Figure 3-3. Gummel plot test conﬁguration

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Keithley Series 2600 Specifications

General

Model	Series 2600
Measurement Functions	Voltage, Current, Resistance, Power
Resolution	Up to 6.5 digits
Current Source Range	Up to 10A
Communication Interfaces	GPIB, USB
Applications	Semiconductor testing
Category	Source Measure Unit (SMU)
Channels	Single or Dual Channel (varies by model)