Antenna-coupling group delay limits the cancellation bandwidth of conventional self-interference cancellers (SICs), making it difficult to ensure isolation in both transmit (TX) and receive (RX) bands. Isolation over both bands is achieved in the dual-path receiver architecture proposed in this paper. The main path consists of a highly linear current-mode RX with a passive RF SIC. The auxiliary path implements a notch in the TX band followed by an adaptive digital equalizer whose output is used to suppress the TX noise leakage in the RX band. The main and auxiliary receiver prototypes, implemented in 28-nm CMOS technology, operate between 1 and 2 GHz, occupy an area of 0.51 and 0.12 mm 2 , and have a power dissipation of 32-40 and 26-64 mW, respectively. The stand-alone RX has a noise figure (NF) of 4-5 dB and an out-of-band IIP3 of 18 dBm. Turning on the passive canceller results in an effective IIP3 of 25-29 dBm and a degradation of the NF of less than 0.8 dB. Thanks to its high dynamic range, the auxiliary path suppresses the TX noise by >29 dB while degrading the RX NF by only 1 dB at 23-dBm TX output power.

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An active self-interference (SI) cancellation technique for SAW-less receiver linearity improvement is proposed. The active canceler combines programmable gain and phase in a single stage and is co-designed with a highly-linear LNA, achieving low noise and low power. A cross-modulation mechanism of the SI canceler is identified and strongly suppressed thanks to the introduction of an internal resistive feedback, enabling high effective receiver IIP3. TX leakage of up to −4 dBm of power is suppressed by over 30 dB at the input of the LNA, with benefits for the entire receiver in terms of IIP3, IIP2, and reciprocal mixing. The design was done in a 40 nm CMOS technology. The system, including receiver and active SI canceler, consumes less than 25 mW of power. When the canceler is enabled, it has an NF of 3.9-4.6 dB between 1.7 and 2.4 GHz and an effective IIP3 greater than 35 dBm.

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