Page 62 - CITS - Electronic Mechanic - TT - 2024

ELECTRONICS MECHANIC - CITS

Benefits of Electronics Circuit Simulation
Circuit simulation provides a critical view into the behavior of electronic circuits. Given the expense and time
involved in fabricating electronic circuits, especially ICs, it’s much more practical to validate circuit behavior and
performance via circuit simulation prior to manufacturing.

Some of the specific area of validation include
Memory Performance: The read and write access times and latency of memory devices are built from analog
circuit simulation of the bit cells and read/write paths inside these memories.
Overall Digital Simulation Accuracy: Digital circuit simulators model the propagation of voltage for logic level 1
and logic level 0. Analog circuit simulation is used to determine the time it takes for a circuit to transition between
these voltage levels. This forms the basis for the overall accuracy of the digital circuit simulator.
Noise and Crosstalk: Higher level models for noise and crosstalk are developed based on the detailed circuit
level analysis of these parasitic effects from analog circuit simulations.
Optimization of High-Frequency and High-Power Circuits: These types of circuits must undergo detailed
continuous time analysis to determine their behavior and performance criteria. Analog circuit simulation delivers
these important analyses.

The overall performance and behavior of complex digital circuits (core processors and AI accelerators are examples)
are verified with digital circuit simulation.
Introduction
So far, we have designed all our circuits by studying basic electronic subcircuit building blocks and then constructing
larger circuits from these. We have designed our circuits by calculating their steady state behavior, as well as their
response to small AC (sine wave) signal deviations from the quiescent state. While this method is useful for coming
up with the overall design of a circuit, it is a slow and limited method for predicting the ideal theoretical behavior
of a circuit under all experimental conditions.

Computer based analog circuit simulator
Computer software circuit simulators are very good at calculating ideal theoretical behavior from Kirchhoff’s Laws.
While circuit simulators will not help you come up with the insight or the creativity to design a good circuit, they are
very useful for helping to elucidate quickly the benefits and disadvantages of one circuit design against another.
Generally, you can simulate a circuit much more quickly than you can build and test it on a breadboard (after a little
practice, of course). The circuit simulator also allows you to try out many variations on a circuit relatively quickly.
The industry standard analog circuit simulation software is SPICE (Simulation Program with Integrated Circuit
Emphasis), which was originally developed at UC Berkeley during the 1970’s and early 1980’s. SPICE (v2G.6) is
the basis for many commercial computer software programs. These programs provide the GUI (Graphical User
Interface) but use the SPICE (or Win SPICE) simulation engine to perform all the circuit calculations.
SPICE does not simulate the electromagnetic fields in a circuit since these depend explicitly on the layout of the
circuit. The results of SPICE can be trusted up to the low MHz range but should be treated with suspicion for
higher frequencies.
B Computer-based circuit layout editor
In the electronics labs, you have designed the layout of your breadboard circuits on the fly. In a professional
setting, the layout of a circuit determines its compactness, ease of use (and debugging), cost, longevity, and its
performance (especially at high frequencies). Several programs exist to help with circuit layout. In fact, in industry,
most electronics engineers will design an abstract circuit with a circuit simulator and then use a software package
to layout the actual circuit on a PCB (Printed Circuit Board). The PCB layout design is then turned into an industry
standard Gerber file which is sent to a PCB production company. A prototype will be assembled and tested at the
engineering company from a PCB board and electronics components, and once it is tested the entire production
is usually contracted out to a third company.
In a physics research lab, the production is done in house, generally. The use of professionally made PCBs is
relatively common, since it generally results in a reproducible circuit, which is likely to work better at high frequencies
than one put together with wires or prototyping boards.

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CITS : E & H - Electronics Mechanic - Lesson 30 - 33