Compounds of the following formula are provided: . A measurement method may include transmitting a first signal from an originator device to a transponder device, the first signal having a first carrier frequency; and determining a carrier phase of the first signal at the transponder device. The inputs of the comparator may comprise a pair of differential inputs at respective source terminals of gate-coupled metal oxide semiconductor devices configured in the input stage of the common-gate amplifier. A disc screen comprising the multi-disc assembly and method of using the multi-disc assembly are also provided.