Automatic Verification Modeling (AVM) -
Power Amplifier Example

MMIC PA Verification Using ADS Wireless Test Benches

Jack Sifri, Agilent Technologies

Verification to Wireless Standards plays an important role in the MMIC Design flow using ADS. Verification to Wireless Standards of large MMIC / RFIC chips prior to manufacturing has been a major barrier in the design flow process. "Results Accuracy" and "Simulation Speed" are the two main factors responsible for this barrier, but now, with ADS Wireless Verification solution and Automatic Verification Modeling (AVM) technology, this barrier has been eliminated.

For efficient simulation the "AVM or Fast Cosim" option of Circuit Envelope simulator can be activated. This option generates a model for the circuit that can be simulated much more efficiently and with very high accuracy.

AVM is a circuit/system co-simulation feature which builds upon the P2D modeling and circuit envelope simulation capability in ADS. This new AVM Co-simulation capability offers a more automated methodology to build an additional level of model abstraction within Agilent Ptolemy to do fast wireless system verification.

ADS is the only EDA design software with the most accurate set of wireless verification tools that provides True Circuit verification to all wireless standards prior to and post fabrication.

ADS Wireless Verification solution:

• Uses Realistic Input Signals and test Benches for all Wireless Standards
• Helps Designers not only test and verify their designs, but also get the most performance out of their circuits.

Example

Here is an example of a WIMAX PA that has been designed in ADS. This Power Amp was inserted into the WIMAX test bench and evaluated for EVM and transmitted waveform spectrum.

The two output plots below show the PA EVM results, once using Agilent's advanced Automatic Verification Model (AVM) technology, and the other one without using the AVM technology.

The case that uses the AVM technology clearly offers high accuracy and speed in the verification process. Using the AVM technology allowed the verification process to run 100 times faster and with high accuracy.

The plot below shows the simulated transmitted output spectrum with respect to the WIMAX Specification Mask, overlaid on top of it. This shows that the spectral re-growth is a minimum and meets the WIMAX Wireless Standards Spec.

Transmitted Spectrum (3525 MHz)

The picture below shows the test bench. It is very easy to use. Designers will only need to insert their PA into the slot as shown below and click on "Simulate".

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Simulation Setup Using Wireless Test Bench

The figure below shows the actual circuit level PA. This PA is simulated using the Circuit Envelope simulator which is embedded inside our Ptolemy System level simulator. All Ptolemy simulation and Co-Simulation with Circuit Envelope are done seamlessly and simultaneously.

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Power Amplifier Schematic

To recap, this demo example has shown the following features on the MMIC PA Verification Solution in ADS:

• Accuracy of our WIMAX verification test bench
• Ease of use of the verification process. Just insert the amp and simulate.
• Speed of our verification using our advanced AVM / Fast Co-simulation capability.
• The transmitted spectrum with respect to the Wireless Standards Specifications Mask.

AVM is shown to increase verification speed by 100 xs in this example. Verification of large chips has been a major obstacle in their successful design and manufacturing. AVM technology is shown here to be one nice solution for the verification of big RFICs. Without AVM from EEsof, you can't efficiently verify a large MMIC or RFIC against wireless standards.

For more information on ADS Wireless Test Benches and AVM technology, click on the following links:

• Wireless Test Benches
• Automatic Verification Modeling (AVM)

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