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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.
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Optimizing the LO Distribution Architecture of mm-Wave Massive MIMO Receivers
Wireless networks at millimeter wavelengths have significant implementation difficulties. The path loss at these frequencies naturally leads us to consider antenna arrays with many elements. In these arrays, local oscillator (LO) generation is particularly challenging since the LO specifications affect the system architecture, signal processing design, and circuit implementation. We thoroughly analyze the effect of LO ar- chitecture design choices on the performance of a mm-wave massive MIMO uplink. This investigation focuses on the tradeoffs involved in centralized and distributed LO generation, correlated and uncorrelated phase noise sources, and the bandwidths of PLLs and carrier recovery loops. We show that, from both a performance and implementation complexity standpoint, the op- timal LO architecture uses several distributed subarrays locked to a single intermediate-frequency reference in the low GHz range. Additionally, we show that the choice of PLL and carrier recovery loop bandwidths strongly affects the performance; for typical system parameters, loop bandwidths on the order of tens of MHz achieve SINRs suitable for high-order constellations. Finally, we present system simulations incorporating a complete model of the LO generation system and consider the case of a 128-element array with 16x-spatial multiplexing and a 2 GHz channel bandwidth at 75 GHz carrier. Using our optimization procedure we show that the system can support 16-way spatial multiplexing with 64-QAM modulation.
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- Award ID(s):
- 1642920
- PAR ID:
- 10211206
- Date Published:
- Journal Name:
- ArXivorg
- Volume:
- https://arxiv.org/abs/1911.01339v1
- ISSN:
- 2331-8422
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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