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3706 and 2602A Setup: Read Values go up to compliance

Models 2601, 2602, 2611, 2612, 2635, 2636
Models 2601A, 2602A, 2611A, 2612A, 2635A, 2636A
Models 2601B, 2602B, 2604B, 2611B, 2612B, 2614B, 2634B, 2635B, 2636B
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[email protected]
Posts: 4
Joined: June 18th, 2018, 4:59 am
Country: Singapore

3706 and 2602A Setup: Read Values go up to compliance

Post by [email protected] » November 26th, 2018, 12:13 am


this is the setup that I have ->


the DUT represents the devices that I want to measure, Channel 1 - 12 represent the channels in a keithley 3724 dual 1x30 switch card that is attached to the keithley 3706A. channels 1-9 in the switch card are connected to units, whereas channel 10 is connected to the source of node[2].smua and channel 12 is connected to the sense of node[2].smua.

this is my code:

Code: Select all

number_of_channels = 9
smu_source_channel = 10
smu_sense_channel = 12
nodechannel = node[2].smua
ddelay = 0.020
-- Keithley Setup
nodechannel.nvbuffer2.appendmode = 1
nodechannel.nvbuffer1.appendmode = 1
nodechannel.sense = nodechannel.SENSE_REMOTE
nodechannel.measure.autozero = nodechannel.AUTOZERO_OFF
nodechannel.source.func = nodechannel.OUTPUT_DCAMPS
nodechannel.source.rangei = 0.060
nodechannel.source.limitv = 5.000
nodechannel.measure.rangev = 5.000
nodechannel.measure.nplc = 0.01
nodechannel.source.leveli = 0.050
nodechannel.source.output = nodechannel.OUTPUT_ON
-- Set Source Channel String
channel_number = 1000 + smu_source_channel;
Source_Channel_String = "" .. channel_number
-- Set Sense Channel String
channel_number = 1000 + smu_sense_channel;
Sense_Channel_String = "" .. channel_number

-- Close Source Channel
for i=1,number_of_channels do
	channel_number = 1000 + i
	Channel_String = "" .. channel_number
	-- Close Device Channel
	-- Close Sense Channel
	-- Open Sense Channel
	-- Open Device Channel
nodechannel.source.leveli = 0.001
nodechannel.source.output = nodechannel.OUTPUT_OFF

-- Open Source Channel
for i=1,node[2].smua.nvbuffer2.n do
	print("Read Value:   " .. node[2].smua.nvbuffer2[i] .. "   "..node[2].smua.nvbuffer1[i])

my results are the following:

Code: Select all

Read Value:   5.0018424987793   0.043180655688047
Read Value:   5.0024914741516   0.044660020619631
Read Value:   5.0022573471069   0.043565846979618
Read Value:   5.0026206970215   0.044426143169403
Read Value:   5.0021538734436   0.043837334960699
Read Value:   5.0023880004883   0.044823873788118
Read Value:   5.0022573471069   0.044470239430666
Read Value:   5.0025172233582   0.044711470603943
Read Value:   5.0025949478149   0.04504693672061

It seems that the measured voltage is going up to compliance, the real value for the DUTs should be 2.2V. Please advise.

Andrea C
Keithley Applications
Keithley Applications
Posts: 1271
Joined: October 15th, 2010, 10:35 am
Country: United States

Re: 3706 and 2602A Setup: Read Values go up to compliance

Post by Andrea C » December 4th, 2018, 5:04 pm


I cannot see the images you tried to post.

You are asking to source 50mA at 5V compliance limit.
You are hitting compliance. Also you are successfully sourcing about 45mA.
So this is not an open circuit issue.

The connections as described sound fine.

Seems you have larger resistance than you think and need to permit higher voltage limit to achieve the 50mA. Or you need to get lower resistance in the pathway.

The SMU is programmed for 4-wire remote sensing. Can you clarify about how the force and sense lines are connected through the switching?

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