So what have mixed-signal chipmakers been doing as the industry climbs out of the recession? Just look at the product announcements over the past year, and you’ll discover where companies have been investing their non-recurring engineering dollars, as well as features and specifications representing the state of the art.
MAXIMIZING CHOICES
In industrial applications, chipmakers have been leveraging their design platforms to produce large families of data converters that offer a range of price points and combinations of features. For example, in October, Analog Devices announced 26 new, lowpower, high-speed analog-to-digital converters (ADCs).
The chips all have similar properties, but the company says they include three industry firsts for 16-bit ADCs. First, the 16-bit, 80-Msample/s dual-device AD9269 provides quadrature-error correction (QEC). Second, the AD9266 single-channel, 16-bit converter can be clocked from 80 to 125 Msample/s. Third, Analog Devices says its AD9265 is the smallest-footprint, singlechannel, 16-bit ADC spanning 20 to 80 Msamples/s.
The other 23 single-channel, low-power ADCs expand the company’s 2009 low-power data converter portfolio to 44 different part numbers. Low power is a common theme across all of these parts. Analog Devices says some parts in the latest batch use up to 87% less power than equivalent ADCs already on the market.
The AD9269’s QEC is a term that probably isn’t in every designer’s vocabulary. The chip is intended for I/Q downconversion, and its QEC and dc-offset digital processing blocks adaptively match the amplitude and phase of the I and Q paths for maximum image suppression while correcting dc offset of the I and Q paths.
Seeking the current small-footprint record, the single-channel AD9266 compresses the basic 20- to 80-Msample/s data converter, a sample-and-hold, a voltage reference, a programmable clock, data alignment circuitry, and programmable digital test patterns into a 5- by 5-mm package. Besides the built-in deterministic and pseudorandom test patterns, user-defined test patterns can be entered via the serial programmable interface.
Similarly seeking economies of scale by leveraging common design elements, in July, Linear Technology unveiled a family of 24 ultra-low-power 14- and 12-bit, quad and dual ADCs for applications including wireless, portable medical imaging, and non-destructive testers.
The ADCs operate up to 125 Msamples/s, and Linear says they dissipate as little as one-third the power of competing chips. The flagship product is the quad, 14-bit, 125-Msample/s LTC2175- 14, which dissipates only 558 mW (140 mW per channel). Signal- to-noise ratio (SNR) is spec’d at 73.4 dB, and spurious free dynamic range (SFDR) is 88 dB at baseband.
Options on the different chips in the family include a data output randomizer that reduces digital feedback, seven programmable lowvoltage differential signal (LVDS) output current levels, internal 100-O output termination resistors, and digital-output test patterns.
New releases from Maxim Integrated Products also included the launch of large ADC families. In November, the company announced 18 multi-channel converters with internal references. These devices were designed to give engineers working on automotive designs, portable/battery-powered electronics, solar-powered systems, and system-monitoring applications a high degree of flexibility in selecting resolution, channel count (4/8/12), supply voltage (2.7 to 3.6 V/4.5 to 5.5 V), and reference voltage (2.048 V/4.096 V).
Designated the MAX11600 through MAX11617, the ADCs are available in 8-bit, 188-ksample/s versions (MAX11600-05) and 10- and 12-bit, 94.4-ksample/s versions (MAX11606-17). All 18 are software configurable to support either unipolar or bipolar inputs, as well as single-ended or differential operation. Pin compatibility between many of the devices enables designers to change resolution and channel count without redesigning their board or control software.
Like competing chipmakers, Maxim emphasized low power consumption—down to 350 µA at 188 ksamples/s or 8 µA at 10 ksamples/s or less, with automatic shutdown technology that powers down the ADCs between conversions.
TINY PACKAGES, LOW POWER
For low-frequency portable temperature and pressure sensors, compact systems, or power-supply monitoring, Linear’s LTC2463 offers a small footprint. (Earlier, Linear introduced the LTC2460, LTC2462, LTC2450, and LTC2452 variants.)
This 16-bit, delta-sigma ADC with integral precision voltage reference (10 ppm/°C maximum; 2 ppm/°C typical) and oscillator comes in either a 12-lead, 3- by 3-mm dual flat no-lead (DFN) package or a 4- by 5-mm mini small-outline package (MSOP). It communicates via a two-wire I2C interface and operates from a single 2.7- to 5.5-V supply. It will digitize a ±1.25-V differential input range at output rates up to 60 Hz.
Typical 16-bit dc performance specs include 1-LSB (least significant bit) integral nonlinearity, 2.2-µVRMS transition noise, and 0.01% gain error. It draws 2.5 mA (maximum) at its 60-Hz maximum sample rate with the internal reference active. After each conversion, the ADC enters “nap” mode, reducing supply current. A proprietary input sampling network reduces dynamic input current to less than 50 nA.
In October, Texas Instruments introduced three 730-ksample/s simultaneous-sampling, successive approximation register (SAR) ADCs with high-voltage inputs for applications including multiaxis motor control, simultaneous data acquisition, robotics, power- quality management, and power protection. The ADS8556, ADS8557, and ADS8558 (16, 14, and 12 bits, respectively) feature typical SNRs up to 91.5 dB (on the 16-bit ADS8556).