AC-DC current transfer standards suitable for use below 1 mA and up to 1 MHz

Traceability for AC currents below 1 mA is needed to calibrate calibrators and multimeters at frequencies up to at least 100 kHz. Since the sensitivity of thermal convertors is not sufficient, only transfer standards using amplifiers are suitable. A newly designed combination of an amplifier and a shunt works at higher frequencies up to 1 MHz as well.