N-path filter sections with biquadratic transfer functions

Explicit design formulas are given for elementary N-path sections, with biquadratic transfer functions Tr(p), which consist of first-order RC path networks and multiplier-type modulators actuated by sinusoidal carrier oscillations [higher-degree transfer functions being realisable by cascading elementary sections]. By varying the phase angle between input and output carriers, the transmission zeros of Tr(p), and therefore its character, can be varied over wide ranges.