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

Page 2EE 461 – Digital System Design Spring 2010 Momentum Objectives 1) Create a Microstrip Layout in ADS with a custom substrate stackup 2) View the layout using the 3D Preview 3) Run a Field Simulation and view the S-parameters 4) Run a transient SPICE Simulation using the field-simulation data

Page 3EE 461 – Digital System Design Spring 2010 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

Page 4EE 461 – Digital System Design Spring 2010 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

Page 5EE 461 – Digital System Design Spring 2010 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:

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

Page 7EE 461 – Digital System Design Spring 2010 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”

Page 8EE 461 – Digital System Design Spring 2010 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

Page 9EE 461 – Digital System Design Spring 2010 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)

Page 10EE 461 – Digital System Design Spring 2010 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)