Have you been a situation where you have been invited to a design review for a fellow co-worker? I guarantee a yes to this question, especially for anyone working in design engineering teams. Alright so now you need to re-prioritize and learn everything you can as fast possible about your co-worker’s design. Now that you are going through the numerous pages of the complex hierarchical schematic with your own custom schematic spreadsheet and design checklist you realize there are a few analog circuits, designs, output stages, data rates, digital circuits, power distribution networks that require a second pair of eyes in terms of analysis. From the designer’s toolbox let’s select OrCAD Capture with PSpice Advanced Analysis Simulation. You can validate the following items efficiently Digital Designs: Validate the design trade-offs for the various termination schemes for high speed communication links Communication links ranging from TTL, LVDS, LVCMOS and PCI Generation links have different termination methodologies. Design decisions are based on power supplies, data rates, power dissipation specifications of the resistors, current draw requirements, source and termination impedance on the printed circuit board. This can be modeled in OrCAD capture utilizing passive components and a digital stimulus to emulate the communication link with DC power supplies. Sensitivity analysis and optimizer curve fitter can be utilized to determine the accuracy and value of the termination scheme including DC blocking capacitors. You can also validate mixed-signal designs see the example of a data acquisition system Mixed-Signal Designs: Data Acquisition System s The front-end input stage to an analog to digital converter can be optimized with PSpice advanced analysis. The output stage of a digital to analog converter is shown below in PSpice. The waveform results executed utilizing the PSpice simulation engine provides details on the output of the amplifier and the digital to analog converter. The goal of the simulation is to validate: Current draw requirements of the design including the output drive strength of the op-amp The power dissipation values for the resistors Bias analysis on the feedback circuits for the digital to analog converter Basic functionality analysis with the digital inputs pulled up to 3.3v Sensitivity Analysis and Optimizer You can utilize the sensitivity analysis to validate/select the resistor values in the feedback circuit of the differential amplifier. Modify the passive and active components in the design to modify the output drive strength of the op-amp. For an analog to digital converter the front end analog input stage can be emulated utilizing the sensitivity analysis and optimizer. For more information go to PSpice.com![]()
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