Cadence Allegro PCB Tips & Tricks

Cadence Allegro is a very powerfull PCB design software. However, it is not very intuitive. Here are some Cadence Allegro PCB Tips & Tricks that I wrote down for myself to remember. I will update them to include new items as soon as I would like to memorize more. Read more

Individual Component Temperature Set/Sweep in LTSPICE simulation

LTSPICE allows to set individual device temperature. However, this possibility is not described in documentation. Read more

Passing Parameters to Hierarchical Block in LTSPICE

There were a couple of questions on how to pass parameters to Hierarchical Blocks from main level schematic in LTSPICE. In fact, until recently, I was having troubles doing this. But solution is very simple and strait forward. Read more

Total Harmonic Distortion tests and results, part 2 – 20 KHz performance

Total Harmonic Distortion performance at 20 KHz.

Next step is to test performance of all stages at higher frequencies.  All tests are performed in the same manner as in previous testing.  Inputs of all 4 stages are connected together and transfer function of every stage is modified to have Gain=1 with corresponding loads and at 20 KHz. Read more

Total Harmonic Distortion tests and results

Test setup for THD measurements.

I will use my Total Harmonic Analyzer for LTSPICE to perform these tests. Control script is slightly modified, to decrease test (simulation) time. It is possible to do so, because all schematics are settling fast and we are not looking into very small THD numbers. Signal amplitudes are also of moderate values. Read more

AC performance, part 2. Input capacitance modulation. Load influence.

Modulation of Input Capacitance.

Changing offset causes some changes in the frequency response. While AC analysis is small signal analysis, offset change will show some differences in big signal performance. One part of this change is modulation of Ccb capacitance. Read more

AC performance of 4 output stages.

AC small signal gain, 8 Ohm load.

Overall gain for all 4 stages was evaluated on the following plots.

We will try to use similar colors for all comparison testing. Read more

Undocumented LTSPICE features-solving some of convergence problems using backward Euler integration method.

LTSPICE is surprisingly flexible simulator but some of important options are not described in documentation. One of them is additional method of integration that you can use to address convergence problems. This method is called backward Euler. Read more

In the search of “Holy Grail” of output stages, evaluating performance of Power Amplifier output stages for High-End applications

Performance of output stage plays a significant role in overall performance of audio power amplifier and, together with VAS output stage, may be considered to be the major source of distortions. Read more

Testing TL431 model performance

A couple of test bench schematics were created in order to evaluate TL431 model performance and make a comparison between suggested model and existing ones. Most of test benches correspond to ones described in the datasheet to take chip measurement data and can be used to tweak model parameters to datasheet numbers. TL431 datasheet was used as a reference. Read more

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