A multifrequency quadrature bridge for realization of the capacitance standard at ETL

A quadrature bridge which will be used in the chain of measurements from the QHR to the standard of capacitance at ETL has been developed. The bridge may be balanced at several frequencies including the conventional 10/2π kHz (i.e., ω=10⁴ rad/s). At its present stage of development the bridge achieves a relative standard uncertainty of 2×10^-7 in comparing 1 nF capacitors and 100 kΩ resistors at frequencies from 3/8×10/2π kHz to 10/2π kHz. With further development it is expected that a relative standard uncertainty of about 5×10^-8 will be achieved