Abstract
This paper presents an electronic circuit capable of measuring a small resistance and capacitance change of high and low loss materials as well as its absolute resistance and capacitance. The measuring capability has been obtained by the use of 180° vector method.
The 180° vector method has a advantage that small changes of circuit constants due to a temperature change are cancelled each other because of its completely symmetrical circuit construction, and then the circuit shows very stable and highly sensitive characteristics.
In using the circuit as a capacitance meter, the observed stability was within less than ±0.25mV in terms of zero drift during 6 hours continuous operation at temperature in the range from 5°C to 20°C when the sensitivity was 7mV/10-3pF. When used as a resistance meter, the circuit's stability is superior to that observed when used as a capacitance meter. The measuring frequency ranging from 1MHz to 30MHz can be used.
