Ericsson
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Ericsson Shortens Design Cycle With VisSim / Comm As a member of Ericsson’s RF Advanced Development Group in Research Triangle Park, NC, my job is to evaluate and implement new technologies that will reduce the cost, size and power consumption in our cellular phones and PCS consumer electronic products. To meet our objective, we use VisSim / Comm, a system-level simulation tool that lets us investigate new design concepts and provides first-order results before committing to hardware prototypes. Why VisSim / Comm? We use VisSim / Comm because of its power, reliability and ease to use. VisSim / Comm offers a full complement of communication blocks that, together with a time-domain simulation engine, provides fast and accurate solutions for analog, digital and mixed-mode communication system designs. Moreover, VisSim / Comm’s intuitive block diagram interface makes it easy for us to build, modify and maintain even the most complex communication models. The Challenge: Investigating New Digital Modulation Synthesizer Architectures A recent engineering effort put VisSim / Comm to the test: our group was designing a new digital modulation synthesizer using a novel approach that employed a modified phase-locked loop (PLL) circuit. The new concept involved generating the desired digital modulation at the output of the synthesizer’s voltage- controlled oscillator (VCO) by appropriately manipulating the phase within the PLL’s feedback loop. This approach would eliminate the need for a subsequent I/Q modulator stage, resulting in board real estate and cost savings. Our challenge was to prove the feasibility of this new synthesizer design without an extensive hardware prototype development cycle. Using VisSim / Comm, we needed to create a block diagram model of the modulation synthesizer and then predict its theoretical performance mathematically through appropriate simulations. The Solution: VisSim / Comm We began the design process by modeling the synthesizer using a standard order PLL. By adding a phase rotation element in the feedback path after the VCO, we were able to make the necessary modifications to the PLL. VisSim / Comm ™ COMMUNICATION SYSTEM DESIGN SOFTWARE By Charles Gore, Research and Development Engineer, Ericsson, Inc. CASE STUDY "If it doesn't work mathematically, it won't work on the bench! Using VisSim/Comm, we designed a new modulation synthesizer much faster than if we had followed the conventional hardware prototype cycle for proof-of-concept. We were able to validate our approach in a matter of days as opposed to the several weeks required to design, assemble, and test a breadboard." – CHARLES GORE, R & D ENGINEER, ERICSSON Ericsson mobile phone. (Continued on back) Synthesizer control loop modeled in VisSim/Comm.
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Ericsson Telecoms Technical Brochure
Transcript of Ericsson
Ericsson Shortens Design Cycle With VisSim/CommAs a member of Ericsson’s RF Advanced Development Group in Research TrianglePark, NC, my job is to evaluate and implement new technologies that will reduce thecost, size and power consumption in our cellular phones and PCS consumer electronicproducts. To meet our objective, we use VisSim/Comm, a system-level simulation toolthat lets us investigate new design concepts and provides first-order results beforecommitting to hardware prototypes.
Why VisSim/Comm?
We use VisSim/Comm because of its power,reliability and ease to use. VisSim/Commoffers a full complement of communicationblocks that, together with a time-domainsimulation engine, provides fast and accurate solutions for analog,digital and mixed-mode communication system designs. Moreover,VisSim/Comm’s intuitive block diagram interface makes it easy for us to build, modify and maintain even the most complexcommunication models.
The Challenge: Investigating New Digital ModulationSynthesizer Architectures
A recent engineering effort put VisSim/Comm to the test: our groupwas designing a new digital modulation synthesizer using a novelapproach that employed a modified phase-locked loop (PLL) circuit.
The new concept involved generating the desired digital modulation at the output of the synthesizer’s voltage-controlled oscillator (VCO) by appropriately manipulating the phase within the PLL’s feedback loop. Thisapproach would eliminate the need for a subsequent I/Q modulator stage, resulting in board real estate and cost savings.
Our challenge was to prove the feasibility of this new synthesizer design without an extensive hardwareprototype development cycle. Using VisSim/Comm, we needed to create a block diagram model of themodulation synthesizer and then predict itstheoretical performance mathematically throughappropriate simulations.
The Solution: VisSim/Comm
We began the design process by modeling thesynthesizer using a standard order PLL. Byadding a phase rotation element in the feedbackpath after the VCO, we were able to make thenecessary modifications to the PLL.
VisSim/Comm™
COMMUNICATION SYSTEM DESIGN SOFTWARE
By Charles Gore,Research andDevelopment
Engineer,Ericsson, Inc.
C A S E S T U D Y
"If it doesn't workmathematically, it won't work onthe bench! Using VisSim/Comm,we designed a new modulationsynthesizer much faster than ifwe had followed the conventionalhardware prototype cycle forproof-of-concept. We were able tovalidate our approach in a matterof days as opposed to the severalweeks required to design,assemble, and test a breadboard."
– CHARLES GORE,R & D ENGINEER, ERICSSON
Ericsson mobile phone.
(Continued on back)
Synthesizer control loop modeled in VisSim/Comm.
For more information or to download a demo version ofVisSim/Comm, contact Visual Solutions at 1 (800) VISSIM-1
or visit our web site at www.vissim.com
487 Groton Road • Westford, Massachusetts 01886 • Tel: (978) 392-0100 • Fax: (978) 692-3102 • Email: [email protected].
Ericsson Shortens Design Cycle With VisSim/Comm (Continued)
Coupled with the suitable control logic, this configuration wouldintroduce either a +90° or -90° phase rotation in the feedback signal toproduce the desired BPSK modulation at the output of the synthesizer.
During simulation, we dynamically tuned all the key PLL parameters toachieve the required transient behavior and produce the preferredmodulated output. A simplified portion of the simulation model isshown on the front page. It includes the synthesizer control loop anddata-driven phase shift logic. The output plot shows the input digitaldata signal and corresponding synthesizer output. For reference, thelocal oscillator output is also shown to illustrate the BPSK modulationeffect at the output of the VCO.
Based on the simulation results, a hardware prototype was successfullybuilt with minimal changes to the actual design.
Future plans now include implementation of this approach in an ASIC,which could potentially be used in millions of digital cellular phones.We have also applied for a patent for this new design.
The Benefits
Much of the success of this project is owed to VisSim/Comm. Using VisSim/Comm, we designed a newmodulation synthesizer much faster than if we had followed the conventional hardware prototype cycle for proof-of-concept. We were able to validate our approach in a matter of days as opposed to the several weeks required todesign, assemble and test a breadboard.
In addition, the task of convincing upper management to pursue this innovative approach would have been muchmore difficult without the results obtained from the VisSim/Comm simulations.
Overall, using VisSim/Comm shortened our design cycle and simplified the development of new and innovativearchitectures for the next generation of Ericsson transceiver products.
General VisSim/Comm Sample Plots
"VisSim/Comm makes it easierfor us to develop innovativearchitectures for the nextgeneration of Ericssontransceiver products. We keepfinding new applications for thisuseful tool. Most recently, wehave been using VisSim/Commto investigate how tocompensate for the effects ofnonlinearities in certain receiverarchitectures."
– CHARLES GORE,R & D ENGINEER, ERICSSON
Chebyshev bandpass filter response obtained by computing the FFT of its impulse response.
VisSim-generated bit error rate curve. Lowpass equivalent power spectrum of a 2 kbps QPSK modulated signal.
COPYRIGHT © 1999 VISUAL SOLUTIONS, INC. ALL RIGHTS RESERVED. VISSIM IS A TRADEMARK OF VISUAL SOLUTIONS, INC. ALL OTHER TRADEMARKS OR REGISTERED TRADEMARKS ARE THE PROPERTY OF THEIR RESPECTIVE OWNERS.
