Four terminal pair digital sampling impedance bridge

This paper describes digital sampling bridge for impedance measurement up to few tens of kHz in four terminal pair definition. It is primarily dedicated for low impedance measurements with comparison currents over 10 A however it can be used at least up to few tens of kΩ as well. Achieved uncertainty for near unity impedance ratio is few μΩ/Ω and the phase angle uncertainty at 1 kHz is few μrad (coverage factor k = 2). Due to the used signal processing method the bridge can be used even for sub-10mV voltage drops on the standards.