Quadrature detector using a double balanced differential circuit and a constant current circuit

摘要

A quadrature detector comprising a double balanced differential circuit including a constant current circuit, and a phase shifter circuit. The constant current circuit comprises a plurality of transistors having their collectors connected together, their bases connected together and their emitters connected to a reference potential level through respective resistors. By the arrangement of the constant current circuit, a current density in the transistors is reduced, a noise generated by the constant current circuit is reduced and hence the S/N ratio of the quadrature detector is improved.