An AC/DC active attenuator for comparison of TVC with different input voltages

The paper describes a system for generating a voltage in a well-established ratio to the input to be used for direct comparison of thermal voltage converters having different nominal voltages. The output voltage is generated by a resistive attenuator followed by a buffer. A feedback control system, driven by the difference between the buffer and the suitable ratio standard outputs, adjusts the voltage to the desired value. The feedback system can easily reduce the difference between the buffered and the reference outputs under 1 μV, both in dc and in ac enabling the direct comparison of converters of any nominal voltage with a multijunction or single junction thermal converter, at an uncertainty level of a few parts in 10⁶