Bringing digital to analog interface

Article By : Don Dingee

The biggest force in analog transformation today is digital integration—a broader concept than mixed-signal fab processes.

Lately, many electronics observers rave over massive digital chips, and for a good reason. Incredible things happen when billions of tiny transistors, each a few nanometers wide, work together. These processors enable the widely touted digital transformation with digitization reshaping entire industries. But where does the data fueling this change come from? A less obvious yet profound analog transformation is happening, as we’ll see in this state of analog overview.

Analog technology takes readings, connects wireless devices, and directs sounds and movements. Analog also manages the electrical power flowing through our digital devices. At so many points, where our digital devices touch the real world, analog is there.

A sizeable chunk of the analog market is at steady state. General-purpose transistors like the 2N2222 that introduced many of us to analog are still around today. There are innovation highlights in discretes, for sure, and more reliable IGBTs still play a critical role in power switching. RF transistors use advanced materials like gallium nitride (GaN) for higher frequencies. But discrete transistor design still requires in-depth knowledge, even with analog EDA tools.

Moving to optimized, integrated functions

In the op-amp category, general-purpose is still a thing. The venerable LM741 is heading into its seventh decade. On the other hand, specialty op-amps have become a bigger thing. There are many choices: high precision, low power consumption, higher current output, and more. A rail-to-rail breakthrough produces lower voltage operation, such as 3.3 VDC, instead of ±12 VDC once required.

There are even more advanced op-amps targeting specific applications. Audio is an ideal use case because of its narrow frequency range for performance optimization. Several manufacturers focus on audio op-amps with ultra-low noise and total harmonic distortion (THD).

RF power amplifiers are also a growing category. These parts need few external components and come in small packages. They often optimize standby power and transmit power consumption. Wireless designs are much easier with already-done analog optimization.

Figure 1 The linearizer IC uses the PA output and input signals to adaptively generate an optimized correction function. Maxim Integrated

Higher levels of integration reveal more sweeping changes in analog. Start with analog-to-digital (A/D) and digital-to-analog (D/A) conversion that delivers benefits from tighter integration. Motion control is one area seeing results. Specialized devices provide current feedback, position feedback, resolver to digital conversion, and more. Instead of reinventing control from generic parts, designers can combine proven integrated chips.

Power management is another major focus of integration, especially where size, weight, power and cost (SWaP-C) is important. Switch-mode conversion efficiency enables smaller designs with longer battery life. Moreover, integrated power management ICs handle the sequencing of many supply voltages in complex system designs.

Bringing digital right up to analog interface

By far the biggest force in analog transformation today is digital integration—a broader concept than mixed-signal fab processes. A sure way to combat analog noise and variation is working in digital where possible. Digital integration is driving dramatic changes in analog system design.

More and more, MEMS sensors have a microcontroller in-package. Instead of an analog stream needing external A/D conversion, these sensors deliver data on I2C or SPI. Digital calibration and compensation in the sensor make readings ready for use. Sampling and filtering are controlled digitally as well. Sensor fusion can increase accuracy, for example, by merging readings from accelerometers and gyros.

A trend toward MIMO antennas and phased arrays is also driving change. Analog front ends (AFEs) enable equalization, beamforming, and more RF processing for array elements. This approach can enhance channel estimation and optimize power, and enable dynamic spectrum use.

Figure 2 RF data converters combine high-performance analog and digital signal processing for a range of wireless designs. Source: Analog Devices Inc.

Sensor systems are also using AFEs for configuration. Another change coming to sensor systems is machine learning (ML). In large sensor networks, sending all that data somewhere for processing can chew up network bandwidth. Here, the ML-enabled sensors can refine a control model, then send raw data only if asked for or when out-of-bounds conditions arise.

Digital-first designers coming in

Recently, Global Industry Analysts sized the 2020 analog IC market at $56.3 billion, growing at 4.8% CAGR through 2027. Yet, digital integration is just getting rolling in this sweeping analog transformation. Digital-first designers see they can use these integrated parts without being analog experts. This trend should expand the market in new and exciting ways.

Without analog, there is no digital transformation. Here at Planet Analog, I’ll focus on helping makers, IoT designers, and system engineers discover, add, and use analog capability. That might help some analog engineers, too. I look forward to hearing from you as we learn together.

After spending a decade in missile guidance systems at General Dynamics, Don Dingee became an evangelist for VMEbus and single-board computer technology at Motorola. He writes about sensors, ADCs/DACs, and signal processing for Planet Analog.

This article was originally published on Planet Analog.

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