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In this paper, we considered four different interference suppression algorithms in a single-input multiple-output receiver, where channel diversity is intentionally introduced to improve interference tolerance. Matched filter (MF), zero forcing (ZF), blind interference estimation and suppression (BIES) which we had previously proposed, and minimum variance distortionless response (MVDR) are considered. Each algorithm is introduced, and the recombining weight vectors are derived. A loss function is defined to compare the performance of the algorithms, showing superior performance of MVDR, and confirming that the proposed BIES algorithm achieves a comparable performance to MVDR. The four algorithms are then applied on measured data from a chip that was designed and fabricated in \qty{45}{\nm} RF SOI process for the frequency range of 1.2-2.4GHz. Measurement results are compared for the four algorithms, confirming significant improvement by using MVDR, BIES, and ZF compared to MF for large interference, as predicted by the derived equations, and showing adaptability of MVDR and BIES to small levels of interference as opposed to ZF. 

This paper presents a novel system architecture to suppress in-band artifacts (IBAs) generated from out-of-band (OOB) interferers, including reciprocal mixing by the local oscillator's (LO) spurs and phase noise (PN), third-order intermodulation (IM3) artifacts, and harmonic down-conversion (HDC) artifacts. Theory and design procedure are explained, and measurement results from a prototype taped out in 45nm RF SOI process are presented. The receiver was designed for the frequency range of 1.2-2.4GHz and achieved a noise figure (NF) of 3.1-6.2dB, blocker -1dB compression point (B1dB) of -10.3Bm, and OOB third-order input-referred intercept point (IIP3) of 9.3dBm on average, before artifact suppression. Measurements were performed on 16-quadrature amplitude modulated (16QAM) signals with modulated and unmodulated OOB interferers to show artifact suppression for various kinds of IBA. For each IBA, artifact suppression performance was assessed across frequency and interferer power. Interference tolerance improvement of up to 38dB was achieved. Additionally, reconstruction of the artifacts for the cases of spur and HDC was demonstrated, showing simultaneous recovery of two signals, providing a form of carrier aggregation. 

Dynamic spectrum access relies fundamentally on the ability to tune radio transceivers to frequencies that are deemed to be available. Consequently, radio hardware must support tuning over a wide range of frequencies. For the receiver, this precludes the use of fixed frontend filters to reject out-of-band interfering signals. Instead, widely tunable receivers rely on filtering after down-conversion either at IF or baseband. This approach relies on linearity and an ideal mixer to keep the desired signal and interfering signals separated. However, practical receivers exhibit non-linearity, phase noise, and oscillator spurs that cause mixing of the signal of interest and interfering signals. As a result, portions of the interfering signals may appear in the band of the desired signal; this causes interference that cannot be mitigated by filtering. Synthetic diversity mitigates this problem by combining analog and digital processing techniques. In the analog domain, the wide-band RF signal is passed through a passive, lossless multi-port diversity network. Each output from this network is then down-converted and digitized so that multiple versions of the signal are available at digital baseband. As the desired signal and the interfering signals experience different frequency response as they pass through the diversity network, it is possible to employ beam forming methods in digital baseband processing to mitigate the interfering signals while preserving the desired signal. The performance of the proposed synthetic diversity receiver is analyzed and it is shown that excellent interference rejection can be achieved. Rejection performance can be increased even further when the circuit elements in the diversity network can be adapted.