Dual-loop transmit noise cancellation

摘要

A transmitter circuit is described. The transmitter circuit includes a first local oscillator that generates a first frequency equal to a duplex frequency. The transmitter circuit also includes a second local oscillator that generates a second frequency equal to a receive frequency. The transmitter circuit further includes a first mixer that combines the first frequency with a first input signal. The transmitter circuit also includes a first feedback loop. The first feedback loop includes a second mixer that combines the second frequency with a transmit signal and a first filter and a first adder that combines an output of the first mixer with an output of the first filter. The transmitter circuit also includes a third local oscillator that generates a third frequency equal to the receive frequency. The transmitter circuit further includes a third mixer that combines the third frequency with an output of the first adder.

主权项

1. A transmitter circuit comprising:
a first local oscillator, wherein the first local oscillator generates a first frequency equal to a duplex frequency; a second local oscillator, wherein the second local oscillator generates a second frequency equal to a receive frequency; a first mixer, wherein the first mixer combines the first frequency with a first input signal; a first feedback loop, wherein the first feedback loop comprises:
a second mixer, wherein the second mixer combines the second frequency with a transmit signal;a first filter; anda first adder, wherein the first adder combines an output of the first mixer with an output of the first filter; a third local oscillator, wherein the third local oscillator generates a third frequency equal to the receive frequency; and a third mixer, wherein the third mixer combines the third frequency with an output of the first adder.