Active polyphase inverter filter for quadrature signal generation

A quadrature signal generator, comprising:

• a coarse stage capable of generating quadrature output signals that have substantially a 90-degree phase relationship based on a differential input signal;
• and
• at least one refinement stage for refining said 90 degree phase relationship of said output signals from said coarse stage, said refinement stage having,
• a plurality of 0/180 delay circuits each receiving a corresponding quadrature output signal and having a 0-degree output and a 180-degree output, wherein a 0-degree output of a first 0/180 delay circuit is coupled to a 180 degree output of a second 0/180 delay circuit, and
• a plurality of 90/180 delay circuits having inputs coupled to corresponding 0-degree outputs of said plurality of 0/180 delay circuits, wherein a 90-degree output of a first 90/180 delay circuit is coupled to a 180 degree output of a second 90/180 delay circuit.

A quadrature signal generator, comprising:

• a coarse stage capable generating quadrature output signals that have substantially a 90 degree phase relationship;
• and
• at least one refinement stage for refining said 90 degree phase relationship of said output signals, said at least one refinement stage including,
• a first 0/180 delay circuit having an input that receives a first output signal of said quadrature output signals, and having a 0 degree output and an 180 degree output,
• a second 0/180 delay circuit having an input that receives a second output signal of said quadrature output signals, and having a 0 degree output and an 180 degree output,
• a third 0/180 delay circuit having an input that receives a third output signal of said quadrature output signals, and having a 0 degree output and an 180 degree output,
• a fourth 0/180 delay circuit having an input that receives a fourth output signal of said quadrature output signals, and having a 0 degree output and an 180 degree output,
• a first 90/180 delay circuit having an input coupled to said 0 degree output of said first 0/180 delay circuit, and having a 90 degree output and a 180 degree output,
• a second 90/180 delay circuit having an input coupled to said 0 degree output of said second 0/180 delay circuit, and having a 90 degree output and a 180 degree output,
• a third 90/180 delay circuit having an input coupled to said 0 degree output of said third 0/180 delay circuit, and having a 90 degree output and a 180 degree output,
• a fourth 90/180 delay circuit having an input coupled to said 0 degree output of said fourth 0/180 delay circuit, and having a 90 degree output and a 180 degree output,
• wherein said 0 degree output of said first 0/180 delay circuit is coupled to said 180 degree output of said third 0/180 delay circuit,
• wherein said 180 degree output of said first 0/180 delay circuit is coupled to a 0 degree output of said third 0/180 delay circuit,
• wherein said 0 degree output of said second 0/180 delay circuit is coupled to said 180 output of said fourth 0/180 delay circuit,
• wherein a 180 degree output of said second 0/180 delay circuit is coupled to a 0 degree output of said fourth 0/180 delay circuit,
• wherein said 90 degree output of said first 90/180 delay circuit is coupled to said 180 degree output of said fourth 0/180 delay circuit,
• wherein said 180 degree output of said first 90/180 delay circuit is coupled to said 90 degree output of said second 90/180 delay circuit,
• wherein a 180 degree output of said second 90/180 delay circuit is coupled to said 90 degree output of said third 0/180 delay circuit, and
• wherein a 180 degree output of said third 90/180 delay circuit is coupled to said 90 degree output of said fourth 0/180 delay circuit.

A quadrature signal generator, comprising:

• a coarse stage capable of generating quadrature output signals that have substantially a 90-degree phase relationship based on a differential input signal;
• and
• at least one refinement stage for refining said quadrature phase relationship of said output signals from said coarse stage, said refinement stage having,
• a plurality of 0/180 delay circuits each receiving a corresponding quadrature output signal and having a O-degree output and a 180-degree output, wherein a 0-degree output of a first 0/180 delay circuit is averaged with a 180 degree output of a second 0/180 delay circuit, said first 0/180 delay circuit and said second 0/180 delay circuit separated by a third 0/180 delay circuit,
• a plurality of 90/180 delay circuits having inputs coupled to corresponding 0-degree outputs of said plurality of 0/180 delay circuits, wherein a 90-degree output of a first 90/180 delay circuit is averaged with a 180 degree output of a second 90/180 delay circuit, said first 90/180 delay circuit adjacent to said second 90/180 delay circuit.

A method of quadrature signal generation, comprising:

• receiving a differential input signal;
• delaying first and second components of said differential input signal to produce a first set of quadrature signals;
• and
• refining said first set of quadrature signals to reduce phase errors, including
• generating second and third sets of quadrature signals based on said first set of quadrature signals, said second set of quadrature signals substantially in-phase with said first set of quadrature signals, said third set of quadrature signals substantially delayed by 180 degrees relative to said first set of quadrature signals,
• averaging said second set of quadrature signals with corresponding signals in said third set of quadrature signals, so as to produce a fourth set of quadrature signals,
• generating fifth and six sets of quadrature signals based on said fourth set of quadrature signals, said fifth set of quadrature signals delayed by approximately 90 degrees relative to said fourth set of quadrature signals, and said six set of quadrature signals delayed by approximately 180 degrees relative to said first set of quadrature signals,
• averaging said fifth set of quadrature signals with corresponding signals in said six set of quadrature signals, so as to produce a seventh set of quadrature signals, whereby said seventh set of quadrature signals has less phase error than said first set of quadrature signals.

A quadrature signal generator, comprising:

• a differential input having a first and second terminals;
• a coarse stage including a first 90/180 delay circuit coupled to said first terminal of said differential input, and a second 90/180 degree delay circuit coupled to said second terminal of said differential input;
• and
• a refinement stage coupled to an output of said coarse stage including,
• a plurality of 0/180 delay circuits having inputs coupled to corresponding outputs of said first and second 90/180 delay circuits, each 0/180 delay circuit having a 0 degree output and a 180 degree output, said 0 degree output of each delay circuit connected with said 180 degree output of another 0/180 delay circuit that is substantially in-phase with said 0 degree output, and
• a plurality of 90/180 delay circuits having inputs coupled to corresponding outputs of said 0/180 delay circuits, each 90/180 degree delay circuit having a 90 degree output and a 180 degree output, said 90 degree output of each delay circuit connected with said 180 degree output of another 0/180 delay circuit that is substantially in-phase with said 90 degree output.