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1、Harmonic Balance Simulation August 2005 ii Notice The information contained in this document is subject to change without notice. Agilent Technologies makes no warranty of any kind with regard to this material, including, but not limited to, the implied warranties of merchantability and fi tness for
2、 a particular purpose. Agilent Technologies shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing, performance, or use of this material. Warranty A copy of the specifi c warranty terms that apply to this software product is avail
3、able upon request from your Agilent Technologies representative. Restricted Rights Legend Use, duplication or disclosure by the U. S. Government is subject to restrictions as set forth in subparagraph (c) (1) (ii) of the Rights in Technical Data and Computer Software clause at DFARS 252.227-7013 for
4、 DoD agencies, and subparagraphs (c) (1) and (c) (2) of the Commercial Computer Software Restricted Rights clause at FAR 52.227-19 for other agencies. Agilent Technologies, Inc. 1983-2005 395 Page Mill Road, Palo Alto, CA 94304 U.S.A. Acknowledgments Mentor Graphics is a trademark of Mentor Graphics
5、 Corporation in the U.S. and other countries. Microsoft, Windows, MS Windows, Windows NT, and MS-DOS are U.S. registered trademarks of Microsoft Corporation. Pentium is a U.S. registered trademark of Intel Corporation. PostScript and Acrobat are trademarks of Adobe Systems Incorporated. UNIX is a re
6、gistered trademark of the Open Group. Java is a U.S. trademark of Sun Microsystems, Inc. SystemC is a registered trademark of Open SystemC Initiative, Inc. in the United States and other countries and is used with permission. iii Contents 1Harmonic Balance Basics Overview.1-1 Using Harmonic Balance
7、Simulation1-3 License Requirements1-3 When to Use Harmonic Balance Simulation 1-3 How to Use Harmonic Balance Simulation.1-3 What Happens During Harmonic Balance Simulation1-4 Examples in ADS1-5 Single Tone Harmonic Balance Simulation 1-5 Swept Harmonic Balance Simulation .1-8 Reference Equations1-1
8、2 Limitations 1-12 HB Simulation Parameters .1-13 Setting Fundamental Frequencies1-15 Setting Up a Sweep in ADS1-17 Setting Up a Sweep in RFDE.1-19 Setting Up the Initial Guess1-21 Enabling Oscillator Analysis.1-24 Selecting Nonlinear Noise Analysis in ADS1-25 Setting Up Nonlinear Noise Parameters i
9、n RFDE1-30 Setting Up Small-Signal Simulations in ADS1-37 Setting Up Small-Signal Simulations in RFDE .1-38 Defi ning Simulation Parameters.1-39 Selecting a Harmonic Balance Solver Technique.1-41 Backward Compatibility Exceptions1-47 Theory of Operation .1-48 The Simulation Process1-48 Comparing Har
10、monic Balance and Time Domain Simulators1-50 Harmonics and Maximum Mixing Order.1-51 Selecting a Solver.1-55 Reusing Simulation Solutions.1-57 Troubleshooting a Simulation1-59 Selecting the Number of Harmonics.1-59 Reducing Simulation Time1-60 Solving Convergence Problems .1-61 Oversampling to Preve
11、nt Aliasing.1-65 Linearizing Nonlinear Devices1-68 2Harmonic Balance for Nonlinear Noise Simulation Performing a Nonlinear Noise Simulation.2-2 iv Performing a Noise Simulation with NoiseCons .2-4 Nonlinear Noise Simulation Description.2-5 NoiseCon Component Description.2-6 NoiseCon Component2-7 Set
12、ting Up NoiseCon Frequency2-8 Setting Up NoiseCon Nodes 2-9 Setting Up the NoiseCon Misc. Tab2-10 Setting Up NoiseCon PhaseNoise .2-13 3Harmonic Balance for Oscillator Simulation Performing an Oscillator Simulation .3-3 Using OscPort 3-3 Specifying Oscillator Nodes .3-3 Setting Up an Oscillator Anal
13、ysis .3-4 Other Oscillator Analyses.3-4 Performing an Oscillator Noise Simulation .3-6 Examples (in ADS).3-7 Finding the Frequency of Oscillation 3-8 Calculating Large-Signal, Steady-State Oscillation Conditions3-10 Calculating Oscillator Loop Gain3-14 Using OscPort2 for Oscillator Analysis.3-17 Sim
14、ulating Phase Noise Using OscPort.3-25 Simulating Phase Noise with NoiseCons .3-27 Oscillator Simulation Description3-33 Performing VCO Tuning3-34 Measuring Oscillator Loop Gain.3-34 Phase Noise Simulation Description 3-37 How ADS Simulates Phase Noise3-37 Possible Problems with Phase Noise Analysis
15、.3-38 Basic Phase Noise Theory.3-40 Troubleshooting a Simulation3-45 Solving Convergence and Speed Problems.3-45 Correcting for Search Failures3-46 Additional Potential Oscillation Frequencies.3-47 When You Question the Accuracy of Frequency Results.3-48 Simulation Techniques for Recalcitrant Oscill
16、ators.3-49 Using Transient Assisted Harmonic Balance3-51 Large-Signal Loop Gain Analysis.3-52 4Harmonic Balance for Mixers Performing a Basic Mixer Simulation4-3 Examples (in ADS).4-4 Finding Mixer Output Tones4-4 v Performing a Small-Signal Simulation of a Mixer .4-8 Determining Mixer Conversion Ga
17、in.4-11 Determining Mixer Intermodulation Distortion4-15 Determining Mixer Noise4-18 Simulating Mixer Noise with NoiseCons.4-20 Small-Signal Mode Description 4-28 Small-Signal Noise Simulation .4-29 Nonlinear Spot-Noise Simulation4-29 Swept-Noise Simulation .4-30 5Transient Assisted Harmonic Balance
18、 Setting Additional Transient Parameters.5-2 Using a One-Tone Transient for a Multi-Tone Harmonic Balance.5-3 Using Sweeps and Optimization Simulations.5-4 Outputting the Transient Data to the Dataset .5-4 6Harmonic Balance Assisted Harmonic Balance Modes of HBAHB Operation.6-1 HBAHB, Parameter Swee
19、ps, and Noise.6-2 HBAHB and TAHB6-2 HBAHB and Non-Convergence6-2 Index vi Overview1-1 Chapter 1: Harmonic Balance Basics This is a description of Harmonic Balance simulation, including when to use it, how to set it up, and the data it generates. Examples are provided to show how to use this simulati
20、on. Detailed information describes the parameters, theory of operation, and troubleshooting information. Overview Harmonic balance is a frequency-domain analysis technique for simulating distortion in nonlinear circuits and systems. It is usually the method of choice for simulating analog RF and mic
21、rowave problems, since these are most naturally handled in the frequency domain. Within the context of high-frequency circuit and system simulation, harmonic balance offers several benefi ts over conventional time-domain transient analysis. Harmonic balance simulation obtains frequency-domain voltag
22、es and currents, directly calculating the steady-state spectral content of voltages or currents in the circuit. The frequency integration required for transient analysis is prohibitive in many practical cases. Many linear models are best represented in the frequency domain at high frequencies. Use t
23、he HB simulation to: Determine the spectral content of voltages or currents. Compute quantities such as third-order intercept (TOI) points, total harmonic distortion (THD), and intermodulation distortion components. Perform power amplifi er load-pull contour analyses. Perform nonlinear noise analysi
24、s. Refer to the following topics for details on Harmonic Balance simulation: “Using Harmonic Balance Simulation” on page 1-3 explains when to use Harmonic Balance simulation, describes the minimum setup requirements, and gives a brief explanation of the Harmonic Balance simulation process. “Examples
25、 in ADS” on page 1-5 describes in detail how to set up a basic single-point and a swept harmonic balance simulation, using a power amplifi er. “Reference Equations” on page 1-12 “Limitations” on page 1-12 describes the harmonic balance simulators limitations. 1-2Overview Harmonic Balance Basics “HB
26、Simulation Parameters” on page 1-13 describes the dialog box fi elds for the HB Simulation controller. “Theory of Operation” on page 1-48 is a brief description of the harmonic balance simulator. “Troubleshooting a Simulation” on page 1-59 offers suggestions on how to improve a simulation. Chapter 2
27、, Harmonic Balance for Nonlinear Noise Simulation describes how to use the simulator for calculating noise. Chapter 3, Harmonic Balance for Oscillator Simulation describes how to use the simulator with oscillator designs. Chapter 4, Harmonic Balance for Mixers describes how to use the simulator with
28、 mixer designs. Chapter 5, Transient Assisted Harmonic Balance describes how to use the automated TAHB to generate the transient initial guess for the Harmonic Balance simulation. Chapter 6, Harmonic Balance Assisted Harmonic Balance describes how to use HBAHB when performing a multi-tone harmonic b
29、alance simulation so the simulator automatically selects which tones to use in generating the fi nal HB solution. For the most detailed description about setting up, running, and converging a harmonic balance simulation, see the following documentation: If you are using ADS, see Guide to Harmonic Ba
30、lance Simulation in ADS If you are using RFDE, see Guide to Harmonic Balance Simulation in RFDE Using Harmonic Balance Simulation1-3 Using Harmonic Balance Simulation This section describes when to use Harmonic Balance simulation, how to set it up, and the basic simulation process used to collect da
31、ta. License Requirements The Harmonic Balance simulation uses the Harmonic Balance Simulator license (sim_harmonic) which is included with all Circuit Design suites except RF Designer. You must have this license to run Harmonic Balance simulations. You can work with examples described here and insta
32、lled with the software without the license, but you will not be able to simulate them. When to Use Harmonic Balance Simulation Start by creating your design, then add current probes and identify the nodes from which you want to collect data. How to Use Harmonic Balance Simulation For a successful an
33、alysis: Add the HarmonicBalance simulation component to the schematic and double-click to edit it. Fill in the fi elds under the Freq tab: Enter at least one fundamental frequency and the number (order) of harmonics to be considered in the simulation. Make sure that frequency defi nitions are establ
34、ished for all of the fundamentals of interest in a design. For example, mixers should include defi nitions for RF and LO frequencies. If more than one fundamental is entered, set the maximum mixing order. This limits the number of mixing products to be considered in the simulation. For more informat
35、ion on this parameter, see “Harmonics and Maximum Mixing Order” on page 1-51. Choose Auto Select option for Matrix Solver under the Solver tab in the Harmonic Balance controller. For tips on using this option, see “Selecting a Solver” on page 1-55. 1-4Using Harmonic Balance Simulation Harmonic Balan
36、ce Basics You can use previous simulation solutions to speed the simulation process. For more information, see “Reusing Simulation Solutions” on page 1-57. You can perform budget calculations as part of the simulation. For information on budget analysis, see the chapter “Using Circuit Simulators for
37、 RF System Analysis” in the Using Circuit Simulators documentation. You can perform small-signal analysis. Enable the Small-signal option and fi ll in the fi elds under the Small-Sig tab. For details, see Chapter 4, Harmonic Balance for Mixers. You can perform nonlinear noise analysis. Select the No
38、ise tab, enable the Nonlinear noise option, and fi ll in the fi elds in the Noise(1) and Noise(2) dialog boxes. For details, see Chapter 2, Harmonic Balance for Nonlinear Noise Simulation. If your design includes NoiseCon components, select the Noise tab, enable the NoiseCons option and fi ll in the
39、 fi elds. For more information, see Chapter 2, Harmonic Balance for Nonlinear Noise Simulation. If your design includes an OscPort component, enable Oscillator and fi ll in the fi elds under the Osc tab. Chapter 3, Harmonic Balance for Oscillator Simulation focuses specifi cally on simulating oscill
40、ator designs. For details about each fi eld, click Help from the dialog box. What Happens During Harmonic Balance Simulation To perform a harmonic balance simulation, you only need to specify one or more fundamental frequencies and the order for each fundamental frequency. Agilent EEsof EDA recommen
41、ds that all other parameters remain set to their default values. The simulator will set up the simulation in a proper way so that near optimal performance can be achieved without any additional parameter tweaking. For example, with Auto Select as the default choice for selecting matrix solvers, the
42、simulator will determine whether the Direct Solver or the Krylov Solver is more effective for a particular circuit. For multi-tone HB simulations, the simulator will automatically determine whether to use Harmonic Balance Assisted Harmonic Balance (HBAHB) and how to set it up to achieve the optimal
43、simulation speed. Examples in ADS1-5 Examples in ADS This section gives detailed setups to perform these simulations on a power amplifi er: “Single Tone Harmonic Balance Simulation” on page 1-5 applies a single tone to the power amplifi er. This tone and 7 harmonics are analyzed. “Swept Harmonic Bal
44、ance Simulation” on page 1-8 sweeps the input from 500 to 1500 MHz and analyzes the performance of the amplifi er at points along the sweep. Single Tone Harmonic Balance Simulation Figure 1-1 illustrates the setup for simulating a power amplifi er circuit. Figure 1-1. Example setup for a basic harmo
45、nic balance simulation 1-6Examples in ADS Harmonic Balance Basics NoteThis design, HB1.dsn, is in the Examples directory under Tutorial/SimModels_prj. The results are in HB1.dds. 1. From theSources-Freq Domainpalette, select and place aV_1Tonesource on the schematic. Edit the component to set these
46、values: V =0.01 V Freq =20 MHz . This is the fi rst and only fundamental. 2. Ensure that the inputs and outputs of nodes at which you want data to be reported are appropriately labeled. In this example, the output node has been labeled Vout. 3. From theSimulation-HB palette, select and place theHB c
47、omponent on the schematic, then double-click to edit it. Select theFreqtab and edit these parameters: Frequency =20 MHz Order =7 ClickAdd. If this line appears as the second fundamental frequency in the list, select the one above it and clickCut. Make sure that 1 20 MHz 7 is the only line that appea
48、rs in the list of fundamental frequencies. Note With only a single frequency defi ned, the parameter Maximum mixing order is not available. 4.Simulate . When the simulation is fi nished, a Data Display window opens. The following plot illustrates the results of the simulation, showing the fundamenta
49、l and seven harmonics, declining in voltage (Vout) with increasing frequency. Examples in ADS1-7 1-8Examples in ADS Harmonic Balance Basics Swept Harmonic Balance Simulation In this example, the fundamental is swept from 500 MHz to 1500 MHz in 25 MHz steps. At 41 points along the sweep, data is collected for the value of the fundamental and 8 harmonics. Figure 1-2 illustrates the setup for a swept harmonic-balance simulation of a power amplifi er circuit. Figure 1-2. Setup for a swept harmonic balance simulation Examples