Multiusing a TVC Toward Development of TVM-Based Phase Measurement System up to 1 MHz

We had previously proposed a wideband phase measurement system based on the three-voltmeter method using a normal thermal voltage converter (TVC) for measuring the differential ac voltage between two ac voltage signals. Several problems were recorded in our previous system, especially for operations in the wideband frequency range. We have investigated their causes and proposed a few solutions. To overcome these problems, we have proposed an additive calibration for the voltmeters by switching the TVC from the differential input mode into a reversible single-ended input mode. The large error peak problem at higher frequencies has been addressed. We compared our proposed system with the new commercial phase standards up to 1 MHz and confirmed the effectiveness of the additive calibration using the TVC for multiple purposes.