- Charge the capacitor with constant current source and then see how the voltage changes across the capacitor. Assuming ideal capacitor we can find capacitance equal to current / (time rate of change of voltage ). Well this method is simple but not accurate and many multimeter uses this method and there are very cheap so I am not going to this method.
- Apply an AC signal across the RC circuit. Measure the voltage across the resistor or capacitor. The phase shift , amplitude difference between these signals will give as value of the capacitance. This is the method which is widely used in the more sophisticated instruments which cost lakhs. So I am going to use this method.
Friday, January 29, 2010
Home made C-V measurment system
My dual degree project is fixed and I am going to work on Nano devices. So surely I will be doing some HEMT fabrication and there characterization. Most common of electrical characterization is C-V measurement at different frequencies. So first challenge is measuring Capacitance (C) of the device. We had C-V measurement system in our lab but unfortunately it is shifted to electrical department and I am not in mood to go to EE department every time I want to do my measurements. Setting up a new CV setup is costly, A LCR meter from Agilent itself cost Rs 9 Lakh and we are not in mood of spending money on it. So I decided to make our own C-V measurement setup. Now I know some of methods which are used to measure capacitance.
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