By Majeed Ahmad, contributing editor

The exponential
rise in data consumption and the growing use of mobile data and high-speed internet
continue to drive the demand for analog-to-digital converters (ADCs) and
digital-to-analog converters (DACs). According to Research and Markets, the
demand for data converters will grow at a CAGR of 8.9% from 2017 to 2021.

Here are some key
patterns for employing ADC and DAC devices into next-generation electronic designs.

1. RF innovation for 5G
The wireless
industry is steadily moving from 4G to 5G infrastructure, and here, the need
for wide input bandwidth, higher sampling rates, and greater spectral
efficiency is driving innovation in the data converter realm. The 4G and 5G wireless
networks encompass a large number of signal bands, and that makes data
converters a crucial part of the overall RF signal chain.

For a start, a
new breed of data converters now offers direct-to-RF signal synthesis, which simplifies
radio design and lowers overall system cost. Take, for instance, the AD9208
analog-to-digital converter from Analog Devices Inc. (ADI), which features
direct RF signal processing and thus eliminates mixer stages.

ADI is targeting
its new ADCs built on the 28-nm process at multi-band
wireless backhaul designs for 4G and 5G networks. AD9208 facilitates
direct RF sampling of wideband signals beyond 6 GHz, which allows RF engineers
to simplify the front-end filtering.

Fig. 1: The block diagram of ADI’s AD9208 analog-to-digital
converter.

ADI has also made
available a DAC for 4G and 5G multi-band
wireless base stations. It offers direct-to-RF synthesis for up to 6 GHz,
eliminating the need for IF-to-RF up-conversion stage and local oscillation (LO)
generation. AD9172, built on the 28-nm process, can also serve defense electronics and instrumentation use cases
involving gigahertz bandwidth applications.

2. FPGAs with data converters
Another
design venue involving data converters and 5G base stations converges around
FPGAs. The 5G base stations encompass an extensive use of multiple-input
multiple-output (MIMO) radios, and here, FPGAs incorporating the ADC and DAC
circuitry can reduce the design footprint and bill-of-materials (BOM)
complexity.

These
FPGAs can eliminate a wide array of off-chip data converters as well as analog
front-end components like mixers commonly used in base
station designs and can perform direct down-conversion from RF to
digital. The integrated ADCs and DACs also reduce power consumption and remove
the need to support off-chip JESD204 serial links between FPGAs and discrete
data converters.

0518_Trends_Fig-2

Fig. 2: A view of the RF subsystem with integrated ADC and DAC
circuitry in Xilinx’s Zynq SoC device.

The current 4 x 4
and 8 x 8 MIMO radios are struggling with power consumption and board space, so
FPGA suppliers like Xilinx are toying with the idea of deploying data
converters as blocks. Moreover, Xilinx is building these devices around a
FinFET process, which will further boost the energy-efficiency advantage
compared to discrete data converters.

The FPGA
developer is planning to run the 12-bit ADC at up to 4 Gsample/s and the 14-bit
DAC at up to 6.4 Gsample/s in its new FPGA that will also include DSP blocks
tuned for digital mixing and filtering. Engineers at Xilinx are confident that
they can effectively manage the isolation between the analog and digital
sections of the FPGA.

3. MCUs boast intelligent analog
If
FPGAs are becoming a key enabler in 5G base station designs by integrating data
converters, at the lower end of the design value chain, microcontrollers are
doing the same to enable smaller and more energy-efficient IoT designs.

The humble 8-bit
microcontrollers are incorporating analog-to-digital
converters with computation (ADC2)
to provide more accurate analog sensor readings and, ultimately, higher-quality
end-user data. The integrated ADC also facilitates the faster conversion of
analog signals, which, in turn, results in more deterministic system responses.

Microchip’s
new family of microcontrollers, PIC16F18446,
specially designed for sensor nodes, employs 12-bit ADC2 circuitry to carry out
filtering autonomously. But more importantly, the ADC2 features the ability to wake the
MCU core only when needed, which lowers power consumption and allows sensor
nodes to run on small batteries.

0518_Trends_Fig-3

Fig. 3: Microchip has streamlined its PIC16F18446 microcontrollers for enhanced analog
functionality.

Next,
microcontrollers like Microchip’s ATmega4809 are incorporating functions such
as core independent peripheral (CIP) in hardware rather than software. That reduces
the amount of code and lowers the bar on software work. The intelligent analog peripherals
like CIPs can also execute command and control tasks in the microcontroller.

This lowers the
risk of delayed response and facilitates a better end-user experience. The integration of ADCs, and, subsequently,
technologies like CIP, also shows how intelligent analog features are allowing 8-bit
microcontrollers to create more efficient IoT designs.

4. Studio-quality audio
Data
converters are also playing a critical role in enabling the high-resolution
audio content for ultra-high-quality music playback. They help filter the unwanted
noise and provide immunity against high jitter. Secondly, they ensure low power
consumption to maximize the battery life of music playback devices like
headphones.

The
CS43130 digital-to-analog converter from Cirrus Logic is a case in
point. It consumes 23 milliwatts of power, which, according to the audio
chipmaker, is four times less than other high-fidelity DACs available in the
market. And it offers up to 32-bit resolution and 384-kHz sampling rate to
deliver superior audio quality.

0518_Trends_Fig-4

Fig. 4: The DAC chip features non-oversampling emulation mode to
ensure natural sound for consumer devices.

Audio
designers are using such data converters in an analog/digital
filter array to deliver the highest-grade reproduction of digital audio sources
— in other words, music or audio close enough to the originally recorded sound in
the studio.

Summary
The
above highlights show how the growth story in data converters mostly revolves
around the IoT, 5G, and smartphone markets, though military and defense
applications also mark a significant growth venue for data converters. Then
there are telecom and data center segments that continue to drive the ADC and
DAC demand.

Within the data converter
technology realm, parameters such as accuracy, linearity, power efficiency,
repeatability, and sampling rate decide the suitability for specific designs. A
diverse array of data converters can address a matrix of possibilities.