Final Circuit & System Simulation - with Optional Co-Simulation Slide 9-1
What is the final topic in this class? Simulation of your amp_1900 and filters in the receiver system to verify analog performance. Gain (S-21), HB with swept LO, and CE with a CDMA source OPTIONAL: co-simulation if you have time - otherwise, take the CommSys class. Co-simulation: simulation of the entire system using digital circuits and analog circuits together. Constellation, spectrum, etc... Next, a co-simulation overview before starting the lab... Slide 9-2
Co-simulation = digital + analog It is your amp_1900 and filters in the receiver system at the bottom level. On the top level is a Data Flow simulation. Co-simulation is digital & RF/analog circuits simulating together. This is your rf_system with amp_1900. Agilent Ptolemy is a bridge between the DSP and RF/ Analog worlds! What is Ptolemy? Slide 9-3
What is Ptolemy? Agilent Ptolemy is a Timed Synchronous Data Flow Simulator TSDF is a unique Agilent EEsof Innovation Agilent Ptolemy adds timed elements - parameters on signals are t, I, Q, Fc (rf carrier) Benefits: - easy to add real RF effects on signals - more efficient simulations - more accurate modeling of RF effects Slide 9-4
What is Data Flow? Tokens (current or numbers) NODE (or component) Token arc (or wire) NODE (or component) Tokens can also be time stamped - then they become samples. Now you can simulate time and frequency domain impairments such as multi-path and fading... How does it all work? Slide 9-5
Bits can flow into A/RF and out! Co-simulation is simulating an A/RF schematic design with a DSP schematic design. Top Level System Design: DSP network IN A/RF network OUT DSP network A/RF SIMULATORS: The simulator in the A/RF design must use either Transient or Circuit Envelope DSP Schematic Window The A/RF schematic can be any kind of design: amplifier, mixer, PLL, etc... Next, DSP components... Slide 9-6
The DSP components library Many palette selections and additional libraries: The use of these tools is covered in the DSP course and also in part of the CommSys course. 3GPP and WLAN courses are also available. In this class, DSP is only briefly introduced! LAB Slide 9-7
Lab 9: Final System Simulation with amp_1900 and filters Slide 9-8
Steps in the Design Process You are here: Design the RF sys behavioral model receiver Test conversion gain, spectrum, etc. Start amp_1900 design subckt parasitics Simulate amp DC conditions & bias network Simulate amp AC response - verify gain Test amp noise contributions tune parameters Simulate amp S-parameter response Create a matching topology Optimize the amp in & out matching networks Filter design lumped 200MHz LPF Filter design microstrip 1900 MHz BPF Transient and Momentum filter analysis Amp spectrum, delivered power, Zin - HB Test amp comp, distortion, two-tone, TOI CE basics for spectrum and baseband CE for amp_1900 with GSM source Replace amp and filters in rf_sys receiver Test conversion gain, NF, swept LO power Final CDMA system test CE with fancy DDS Co-simulation of behavioral system Slide 9-9
First, set up the sub-circuits & system Use port connectors and the File > Design Parameters Later on, replace the behavioral models with the circuits you built. Slide 9-10
Next, use the Smart Simulation Wizard 1 2 3 Click the icon in schematic and follow the step-by-step dialogs to test AMP_1900 in a 1 Tone HB simulation. 4 Data display of all plots and lists is automatic! 5 6 Slide 9-11
Next, set up and run HB with swept LO power Turn on Display NF and conversion gain appear if status level = 4. Plot: dbm_out vs LO_pwr. Write and list the IF_gain. Final simulation... Slide 9-12
Final system CE simulation with CDMA data Set up envelope simulation with t_step and t_stop variables for CDMA. IF_out equation will be the only data output - save DDS memory! Slide 9-13
ACPR and Power calculations: example DDS 1. Copy an example DDS file. 2. Save it in your system_prj. 3. Pass your data into the display. YOU GET TWO PAGES OF DATA! Change the default dataset name and the equation. All of your data will pass into the plots and equations! Vfund = IF_out Slide 9-14
Marker Slider for CDMA spectrum Set up a marker slider using equations: marker slides to a frequency and the spectrum of that carrier frequency is displayed: RF, LO, IF, etc. Marker value is at the IF: 100 MHz. One more step Slide 9-15
Envelope with Frequency Sweep RF sweep with LO adjusting = same IF (100 MHz) Vout[1] = IF at 3 RF tones harmindex: 1 = 100 MHz FINISHED!!! Optional co-simulation NOTE: If you finish this step in the lab, you have achieved all the goals for this class! Slide 9-16
OPTIONAL - Co-simulation of rf_sys This process requires several steps: First step: Modify the system to become a sub-circuit (bottom CE simulation level) as shown here. Co-simulation requires a Transient or CE simulation setup. In this class, it is easier and faster to set up and run co-simulation using the behavioral system. The Extra exercise shows even more cosimulations you can try after the course! Slide 9-17
Co-simulation continued... Next step: Open a top level DSP network to access the Ptolemy / DSP palettes in schematic. Then build the system shown here: All the steps are in the lab, including the settings for the data components, filters, etc. The t_step and t_stop are now set for symbol rate and time. Bottom level system. Data flow controller runs showing filtered bits and IF signal: TkXY plots Slide 9-18
Data Flow simulation - TK plots are active! Quit the DF simulation and connect a SpectrumAnalyzer sink to collect the data. Results of this co-simulation show spectrum of the behavioral system. To use amp_1900 and your filters, replace them in the system and setup a new simulation (requires more time). Start the lab now! Spectrum Analyzer sink: Slide 9-19
End of the Course Goodbye and see you next time! www.agilent.com Agilent EEsof EDA - Customer Education Slide 9-20