GaN based active cancellation circuit for high power simultaneous transmit and receive systems

摘要

A cancellation circuit for a simultaneous transmit and receive system includes a variable attenuator, a variable coarse true time delay a variable fine true time delay, the variable fine true time delay having a cancellation signal output, a circulator coupled to a transmit signal and having a receive signal input and having an output having a sum of the receive signal and a leakage signal, the leakage signal being a portion of the transmit signal leaking through the circulator, a 180° hybrid having a delta output having a difference between the sum of the receive signal and a leakage signal and the cancellation signal, and a control circuit coupled to the delta output and the variable attenuator, the variable coarse true time delay, and the variable fine true time delay to adjust an amplitude and phase of the cancellation signal.

主权项

1. A cancellation circuit for a simultaneous transmit and receive system comprising:
a coupler coupled to a transmitter for providing a portion of a transmit signal; a variable attenuator coupled to the coupler; a variable coarse true time delay coupled to an output of the variable attenuator; a variable fine true time delay coupled to an output of the variable coarse true time delay, the variable fine true time delay having a cancellation signal output; a circulator coupled to the transmit signal and having a receive signal input and having an output having a sum of the receive signal and a leakage signal, the leakage signal being a portion of the transmit signal leaking through the circulator; a 180° hybrid having a first input coupled to the cancellation signal output of the variable fine true time delay, a second input coupled to the output having the sum of the receive signal and the leakage signal, and a delta output having a difference between the first input and the second input, the delta output coupled to a receiver; a power detector coupled to the delta output; and a control circuit coupled to the power detector, the control circuit coupled to the variable attenuator, the variable coarse true time delay, and the variable fine true time delay to adjust an amplitude and phase of the cancellation signal.