EELE 461/561 – Digital System Design

1. EELE 461/561 – Digital System Design ADS MoMentum EE 461 – Digital System Design Spring 2010

2. Momentum • Objectives1) Create a Microstrip Layout in ADS with a custom substrate stackup2) View the layout using the 3D Preview3) Run a Field Simulation and view the S-parameters4) Run a transient SPICE Simulation using the field-simulation data EE 461 – Digital System Design Spring 2010

3. Momentum • Part 1: Create a Microstrip transmission line layout- create a new design- enter the MLIN and MSUB components from the T-lines – Microstrip library- enter the desired parameters for the substrate and microstrip EE 461 – Digital System Design Spring 2010

4. Momentum • Part 1: Create a Microstrip transmission line layout- Using the pull-down menu in the schematic, perform: - Layout – Update/Generate Layout - In the layout, use the pull-down menus to perform: - Momentum - Substrate –Update from Schematic EE 461 – Digital System Design Spring 2010

5. Momentum • Part 1: Create a Microstrip transmission line layout- Enter two ports to your microstrip structure using the pull-down menus: - Insert – Port (accept defaults) - Rotate and attach to the microstrip as in the following figure: EE 461 – Digital System Design Spring 2010

6. Momentum • Part 2: View the structure using the 3D Previewer- Using the pull-down menus, perform: - EMDS – 3D EM Preview EE 461 – Digital System Design Spring 2010

7. Momentum • Part 3: Run a field simulation- Using the pull-down menus, perform: - Momentum – Substrate – Precompute - Set the frequency range to (100 MHz to 10GHz) and click OK- Using the pull-down menus, perform: - Momentum – Simulation – S-parameters - On the right of the screen, enter: - Sweep Type = Log - Start = 100 MHz - Stop = 10 GHz - Points/Decade = 5 - Click “Update” to add to Frequency Plan - Click “Simulate” EE 461 – Digital System Design Spring 2010

8. Momentum • Part 3: View the S-parameter Results- The S-parameters for all ports will automatically appear when the field simulation completes.- You should change the frequency axis to LOG EE 461 – Digital System Design Spring 2010

9. Momentum • Part 4: Run a transient simulation using the field-solver data- Back in the schematic, enter a full schematic using your Gaussian 35ps step (the figure below shows an ideal step) EE 461 – Digital System Design Spring 2010

10. Momentum • Part 4: Run a transient simulation using the field-solver data- Run the transient simulation and observe the performance of the microstrip line - notice the impedance discontinuity on the TDR - notice the frequency dependant loss on the TDT (i.e., the slow tail) EE 461 – Digital System Design Spring 2010