Patent ID: 8552782

Claim:
A quadrature filter network comprising: a differential quadrature all-pass filter defining an input port and a pair of output ports comprising a first output port having an output I+ terminal, and an output I− terminal and a second output port having an output Q+ terminal, and an output Q− terminal, at which nominally mutually quadrature signals are generated; a resistance-reactance filter defining a pair of input ports, comprising a first input port having an input I+ terminal, and an input I− terminal; and a second input port having an input Q+ terminal, and an input Q− terminal and also defining at least an output port, said pair of input ports of said resistance-reactance filter being coupled to said pair of output ports of said differential quadrature all-pass filter, and wherein the input I+ terminal of the resistance reactance filter is connected to the output I+ terminal of the quadrature all-pass filter; the input I− terminal of the resistance reactance filter is connected to the output I− terminal of the quadrature all-pass filter; the input Q+ terminal of the resistance reactance filter is connected to the output Q− terminal of the quadrature all-pass filter; and the input Q− terminal of the resistance reactance filter is connected to the output Q+ terminal of the quadrature all-pass filter.