APPLICATION NOTE
Ensuring Accurate Broadband EM Analysis
with Allegro PCB Designer
This application note outlines the electromagnetic (EM) simulation and verification flow
between the Cadence
®
Allegro
®
PCB Designer and Cadence AWR Design Environment
®
platform, specifically AWR
®
Microwave Office
®
circuit design software and the AWR AXIEM
®
EM simulator for a PCB design. The example uses a simple transmission line with known
response to validate the approach and demonstrate interoperability between design and
analysis tools. Following the export/import steps, the creation of an EM simulation structure
is shown and the tradeoffs between design complexity and simulation time are discussed.
Lastly, an introduction to basic EM port configuration and simulation settings is provided and
a comparison of the AWR AXIEM EM simulation against measured results is shown.
Design Overview
One of the less complex PCB structures for RF applications is the two-port, 50 Ω transmission line, also known as a "thru
line". The thru line is often used to calibrate test equipment, such as a vector network analyzer, supporting calibration of a
reference measurement plane at the middle of the PCB when combined with other PCB-based calibration standards. The
structure used in this application note varies from a simple thru line by including two narrower, slightly higher impedance
transmission line sections to address the impedance mismatch introduced by the coax-to-microstrip transition, as well as a
pair of transmission line discontinuities separated by small section of 50 Ω line. The supporting coax-to-PCB transitions
and discontinuities can be replicated and modeled with a combination of planar and 3DEM simulation tools. The PCB
consists of a transmission line, two discontinuities, and ground via arrays. Step-by-step instructions are provided for how
to export a PCB design created in Allegro PCB Designer via an IPC-2581 compatible file and then import the file into AWR
Design Environment platform through the PCB import wizard.
