Toward Solving Multichannel RF-SoC Integration Issues Through Digital Fractional Division

Files in This Item:
File Description SizeFormat 
2016-03_tvlsi_mehr_coupling.pdf3.78 MBAdobe PDFDownload
Title: Toward Solving Multichannel RF-SoC Integration Issues Through Digital Fractional Division
Authors: Mehr, Seyed Amir Reza AhmadiTohidian, MassoudStaszewski, Robert Bogdan
Permanent link:
Date: 12-Jun-2015
Online since: 2017-05-10T10:16:49Z
Abstract: In modern RF system on chips (SoCs), the digital content consumes up to 85% of the IC chip area. The recent push to integrate multiple RF-SoC cores is met with heavy resistance by the remaining RF/analog circuitry, which creates numerous strong aggressors and weak victims leading to RF performance degradation. A key such mechanism is injection pulling through parasitic coupling between various LC-tank oscillators as well as between them and strong transmitter (TX) outputs. Any static or dynamic frequency proximity between aggressors (i.e., oscillators and TX outputs) and victims (i.e., oscillators) that share the same die causes injection pulling, which produces unwanted spurs and/or modulation distortion. In this paper, we propose and demonstrate a new frequency planning technique of a multicore TX where each LC -tank oscillator is separated from other aggressors beyond its pulling range. This is done by breaking the integer harmonic frequency relationship of victims/aggressors within and between the RF transmission channels using digital fractional divider based on a phase rotation. Each oscillator's center frequency can be fractionally separated by ~28% but, at the same time, both producing closely spaced frequencies at the phase rotator outputs. The injection-pulling spurs are so far away that they are insignificantly small (-80 dBc) and coincide with the second harmonic of the carrier. This method is experimentally verified in a two-channel system in 65-nm digital CMOS, each channel comprising a high-swing class-C oscillator, frequency divider, and phase rotator.
Funding Details: European Research Council
Type of material: Journal Article
Publisher: IEEE
Journal: IEEE Transactions on Very Large Scale Integration (VLSI) Systems
Volume: 24
Issue: 3
Start page: 1071
End page: 1082
Copyright (published version): 2015 IEEE
Keywords: Frequency modulationOscillatorsCouplingsHarmonic analysisRadio frequencyFrequency conversionSubstrates
DOI: 10.1109/TVLSI.2015.2436979
Language: en
Status of Item: Peer reviewed
Appears in Collections:Electrical and Electronic Engineering Research Collection

Show full item record

Citations 50

Last Week
Last month
checked on Jul 2, 2020

Page view(s)

Last Week
Last month
checked on Jul 6, 2020


checked on Jul 6, 2020

Google ScholarTM



This item is available under the Attribution-NonCommercial-NoDerivs 3.0 Ireland. No item may be reproduced for commercial purposes. For other possible restrictions on use please refer to the publisher's URL where this is made available, or to notes contained in the item itself. Other terms may apply.