One of the challenges in direct conversion Doppler radar lies in the dc offset resulted from antenna coupling. The dc offset may saturate the baseband amplifiers, preventing sufficient amplification of the received signal. In this work, a Coupling-Cancellation-Antenna (CCA) was implemented in the radar front end to enhance radar detection accuracy by minimizing the TX-RX antenna coupling. The idea is to have two transmitting antennas fed by signals with 180° phase difference such that the two signals cancel at the RX antenna. As a result, a larger receiver gain can be used to improve the signal to noise ratio without saturating the baseband output. Experimental validations of the CCA concept demonstrate 37-dB reduction in the TX-RX coupling. Furthermore, the CCA method reduces the detection error from 15.8% to 2.4%.
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An FDD/FD Capable, Single Antenna RF Front End from 800MHz to 1.2GHz w/ Baseband Harmonic Predistortion
A highly-integrated dual technology (28nm and 130nm SOI) widely tunable software-defined RF duplexing front-end for FDD, FD, and TDD applications is presented. Predistortion and harmonic upconversion are used to cancel second and third harmonics generated by PA nonlinearity by up to 30 dB. A novel form of non-reciprocal, distributed degeneration is used to suppress TX noise that desensitizes the RX for full duplex operation. The distributed degeneration network improves RX noise figure by 7dB over baseline TX operation for same channel TX-RX. The transceiver achieves a 23dBm output power while maintaining more than 30dB of TX-RX isolation over the 0.8-1.2GHz band.
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- Award ID(s):
- 1641100
- PAR ID:
- 10075237
- Date Published:
- Journal Name:
- 2018 IEEE Radio Frequency Integrated Circuits Symposium (RFIC)
- Page Range / eLocation ID:
- 120 to 123
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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