High Resistance measurement

[chand1]

I want to measure high resistance of the order of 10^12 Ohms ( Tera Ohms), with an accuracy around 5%.
Please suggest a circuit, which i can wire myself. Thanks.

 

[FvM]

Hello,

measuring circuit is rather simple in general, see the principle circuit from Keithley 6517A Electrometer for reference. It uses 400 V voltage source in TΩ range, other parameterss may be easily calculated. Additionally, a high ohmic resistor (≈ 1 to 10 GΩ) and a low input current/ high impedance amplifier are needed. Special "electrometer" amplifiers, e. g. TI OPA 129, Analog AD549 would be recommended for best accuracy, however, also simple CMOS amplifiers as CA3140 could be used for basic measurements. Additionally amplifier input protection should be considered, at least by connecting a series resistor at the amps inverting input.

Regards,
Frank

 

[go2tariq]

I tried this method for meausrement of resistance but it didn't work for me :sad:. I am interested to measure 1 Gig ohm but supply voltage less than 15 v.

Hello,

measuring circuit is rather simple in general, see the principle circuit from Keithley 6517A Electrometer for reference. It uses 400 V voltage source in TΩ range, other parameterss may be easily calculated. Additionally, a high ohmic resistor (≈ 1 to 10 GΩ) and a low input current/ high impedance amplifier are needed. Special "electrometer" amplifiers, e. g. TI OPA 129, Analog AD549 would be recommended for best accuracy, however, also simple CMOS amplifiers as CA3140 could be used for basic measurements. Additionally amplifier input protection should be considered, at least by connecting a series resistor at the amps inverting input.

Regards,
Frank

ΩΩΩ