Abstract
An integrated reconfigurable CMOS quasi-circulator operating at 2.4 GHz is presented. A passive structure delivers transmit power amplifier (PA) output signal to the differential low-noise amplifier (LNA) input as a common-mode signal and simultaneously delivers received signal as a differential-mode signal at the LNA input. The leakage of the PA output signal at the LNA input is reduced in two steps. First, the use of a reconfigurable impedance matching circuit, instead of a fixed 50-Ω resistance reduces the leakage by compensating the antenna impedance mismatch, and improves transmitter-receiver isolation. Second, a reconfigurable summing stage adds amplitude and phase adjusted PA output signal to LNA output to cancel the residual PA output leakage. Measurement results show that the receiver achieves a reduction of 90 dB for a single tone and more than 50 dB for a QPSK modulated 40-MHz bandwidth transmit signal. The receiver gain is more than 10 dB and the noise figure in the receiver path is 4.5 dB. The reconfigurable quasi-circulator along with the receiver LNA is designed and fabricated on a 130-nm CMOS technology. The cancellation circuitry occupies 0.27 mm2 and consumes 30-mW quiescent power, while the total active area of the chip is 1 mm2, and it consumes 65-mW power.
Original language | English (US) |
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Pages (from-to) | 1421-1430 |
Number of pages | 10 |
Journal | IEEE Transactions on Microwave Theory and Techniques |
Volume | 66 |
Issue number | 3 |
DOIs | |
State | Published - Mar 2018 |
Keywords
- Full-duplex wireless
- impedance tuner
- on-chip circulator
- reconfigurable circuit
- self-interference cancellation
- transmit leakage cancellation
ASJC Scopus subject areas
- Radiation
- Condensed Matter Physics
- Electrical and Electronic Engineering