# Connecting HP 4140B pA Meter for VI Curve Measurement

• seang
In summary, the voltage source is coax out, and the current in is via triax. I think I know what connections to make here but could someone help me anyway? The manual for the 4140B is available on the web, and it has some figures that I think are useful.
seang
Hi, I'm trying to make connections with a pA meter / V source. It is a HP 4140B. Let's just say I'm going to try to find the VI curve for a resistor.

The voltage source is coax out. I think I know what connections to make here but could someone help me anyway?

The current in is via triax. I've never worked with one of these. What connections do I make?

I don't know if it helps, but here are some Agilent Application Notes about the 4140B.

http://www.home.agilent.com/agilent/facet.jspx?kt=1&cc=US&lc=eng&k=4140B

It was discontinued in 2000, and I didn't see the manual at the Agilent website, but I only took a quick look. Do you have the manual? You can probably find it on the web somewhere.

BTW, what does pA stand for?

pA=picoamp, 10^-12 A

f95toli said:
pA=picoamp, 10^-12 A

Oooohhhh. Thanks.

But why in the world use a picoAmmeter for making a VI trace of a resistor? Sounds like a square peg headed for a round hole... ?

berkeman said:
Oooohhhh. Thanks.

But why in the world use a picoAmmeter for making a VI trace of a resistor? Sounds like a square peg headed for a round hole... ?

Hes probably measuring a high impedance component.

berkeman said:
Oooohhhh. Thanks.

But why in the world use a picoAmmeter for making a VI trace of a resistor? Sounds like a square peg headed for a round hole... ?

Ha, not actually going to perform that experiment. Just needed an example. In reality I will be measuring VI curves of some films, CNT samples, etc.

btw, if you google HP 4140b, the first link is the manual. There are some figures in there that I suspect are useful, but I can't quite make sense of them.

on page 3-42, the setup shows the triax connected to GND, LOW, and HIGH (I think). If I'm measuring a two terminal device, what do these mean?

seang said:
on page 3-42, the setup shows the triax connected to GND, LOW, and HIGH (I think). If I'm measuring a two terminal device, what do these mean?

Interesting. It looks like they are guarding the high line with the "low" shield to try to have as little voltage difference between the high line and the surrounding shield, to minimize leakage currents. If they just had coax, then there would be the full voltage drop from high to ground between the two conductors, so that full voltage drop will drive a larger leakage current.

This technique is often called "bootstrapping", and is usually done to reduce the effective capacitance between a sensitive line and its surrounding shield. The shield is driven with an opamp buffered version of the inner conductor voltage, so the shield is always at about the same voltage. That way, there is no effective capacitive loading between the inner conductor and the shield -- the opamp is taking care of "bootstrapping" out the effective capacitance.

So make your connections to your 2-lead device as shown on page 3-43, depending on whether you DUT is grounded or floating. Does that make more sense now?

Yeah, I think I get it. Sometimes you just have to talk it out I guess.

Thanks a lot for your help.

## 1. How do I connect the HP 4140B pA Meter for VI Curve Measurement to my device?

To connect the HP 4140B pA Meter for VI Curve Measurement, you will need to use a GPIB (General Purpose Interface Bus) cable. This cable will connect the meter to your device using the GPIB ports on both devices. Make sure to follow the proper connection instructions in the meter's manual.

## 2. What is the purpose of using the HP 4140B pA Meter for VI Curve Measurement?

The HP 4140B pA Meter is used for measuring current and voltage values for a specific device or circuit. With its high accuracy and sensitivity, it is commonly used in research and development settings to analyze the behavior of electronic components and circuits.

## 3. Can I use the HP 4140B pA Meter for VI Curve Measurement with any type of device?

Yes, the HP 4140B pA Meter is compatible with a wide range of devices such as transistors, diodes, and integrated circuits. However, it is important to make sure that the device you are testing is within the meter's measurement range and specifications.

## 4. How do I interpret the VI curve data obtained from the HP 4140B pA Meter?

The VI curve data obtained from the HP 4140B pA Meter is typically displayed on a graph, with current (I) plotted on the y-axis and voltage (V) on the x-axis. The shape of the curve can provide insights into the behavior and characteristics of the device under test. The slope of the curve at a certain point can also indicate the resistance or conductance of the device at that point.

## 5. Can I save and export the VI curve data from the HP 4140B pA Meter for further analysis?

Yes, the HP 4140B pA Meter has a built-in storage function that allows you to save the VI curve data for later analysis. You can also export the data to a computer using the GPIB connection and specialized software. This allows for further analysis and comparison between different measurements.

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