A low cost capacitive bridge based on voltage drop balance

Abstract The proposed bridge has a simple analog design featuring few components and may be implemented inexpensively at any laboratory. Yet, it is characterized by a low input stray capacitance (1 pF in the prototype with margin for improvement) and a very good accuracy, in terms of measurement uncertainty and repeatability: the method of balancing successive readings of the voltage drops across the “capacitor under test” and a reference resistor uses at best the external voltmeter in terms of measurement accuracy and avoid the need for a voltage reference and related stability issues.