Skills For the Coming Market - Analog Design

For a significant period of time in the 2000s through 2010s, it seemed like analog design was left only for the domain of radio designers, medical equipment designers, and academics. Everything moved to digital and started running much faster as more devices became “smart” and everyone’s attention was focused on computers, Moore’s law, and the cloud. Now the landscape for electronics is changing and the analog design skillset is becoming critical again.

Some of the major application areas where analog design is becoming a critical skillset is in precision motor control, sensing across a huge range of frequencies, and electrification. Of course, other areas like wireless and medical still require analog design skills, but these products are having more aggressive form factors that make noise-free design difficult. For the designer that wants to stay at the forefront of market changes, we’ve compiled some of the essential analog design skills engineers and PCB designers should know.

Essential Analog Design Skills

Just about every analog design application area requires some or all of the front-end skills listed below.

Amplifier and Filter Design

Amplifiers and filters are two of the fundamental types of circuits needed in analog design. They are used for many tasks, ranging from noise reduction to level shifting. Inexperienced analog designers are likely to opt for passive filters to remove noise. While passive circuits are useful and they do provide filtering action, the standard practice in analog circuit design is to use op-amps for filtering.

The prospective analog designer should therefore learn some of the standard types of analog filter and amplifier circuits that can be built with op-amps. This includes an understanding of designing feedback into these circuits to provide the desired gain and filtering in analog designs.

Learn more about designing with op-amps

Op-amps are fundamental components in analog circuits.

Op-amps are available in a range of packages (through-hole and surface mount) and with a wide range of specifications. Some ICs allow dense placement of analog circuits with multiple op-amps in a single package. The advantage of using multi-channel op-amp ICs is their small footprint (available as SMD components), which can be used to make analog circuits very compact. This is especially true in analog circuits that require multiple op-amps as these can be placed in a very compact area in a PCB layout.

Simulation Skills

Once a design has been created and built in a schematic editor tool, it needs to be simulated. Analog designers need to know several important skills that can help them evaluate the reliability of their analog systems, especially when precision measurements are needed. Some of the main analog simulation skills needed include:

• Monte Carlo analysis
• Sensitivity analysis
• Smoke analysis
• Pole-zero analysis

The goal in these simulations is to evaluate sensitivity to noise, component tolerances, and temperature, as well as reliability. Pole-zero analysis is also important for analog circuits as excitation of poles is not always obvious from time-domain simulations. This gives you a nice summative metric for determining resonances and antiresonances in an analog circuit, which might need to be suppressed in the design.

Measurement of Analog Signals

Several pieces of equipment are needed to take measurements of analog signals in the time domain and in the frequency domain. As part of debugging prototypes, it’s important to understand how to use these pieces of equipment, as well as how to interpret the measurements. Some important equipment and the electrical quantities they can measure are listed in the table below.

Selection and Placement of ADCs

The border between the digital and analog world is defined by analog to digital converters (ADCs). These components have a simple job: collect an analog signal and convert it into its digital representation. After being output over a digital interface, the translated signal is given to another processor where some DSP steps will be needed to interpret the signal.

Because most analog systems are really mixed-signal systems, it’s important to understand how to floorplan a PCB to ensure an ADC will have noise-free operation. Some of the basic skills involved in ADC usage are as follows:

• Selection of an appropriate ADC for acquisition of the intended signal
• Design of an analog front-end to filter, amplify, or otherwise condition the signal
• Placement of an ADC in a PCB layout with appropriate stackup design to suppress noise
• Routing the digital interface on the output to prevent crosstalk into the analog front-end
• Selection of DSP algorithms and a processor that can run these with low latency

Many systems that have multiple analog interfaces requiring diverse digital interfaces are implementing all the digital processing in FPGAs. These components are useful because they can be used to interface with standard lower-speed digital serial protocols (usually SPI) or the much more powerful JESD204C interface.

Read our complete guide to selecting and using ADCs

Anyone that wants to stay at the cutting edge of analog design needs the best set of design and simulation features to help them reach success. Professional digital and analog engineers trust the complete set of system analysis tools from Cadence for evaluating and simulating their system functionality. Only Cadence offers a comprehensive set of circuit, IC, and PCB design tools for any application and any level of complexity.

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