A parallel phase shift circuit is configured to perform a phase shift process in parallel on an input signal pair including a first I signal orthogonal to a first Q signal, in accordance with a phase difference among a set of n multi-phase separation frequency signal pairs including a set of second I signals orthogonal to a set of second Q signals, to generate a set of n phase-shifted orthogonal signal pairs including a set of third I signals orthogonal to a set of third Q signals; and a phase discrete continuous measurement circuit configured to, based on the n phase-shifted orthogonal signal pairs from the parallel phase shift circuit, generate a set of discrete signals being n discrete values and generate a set of continuous tangent signals being a set of a desired number of signals interpolating the set of discrete signals.