Sample-quantity pricing at introduction (late June) was $34. ADI also introduced a 6-Msample/s companion, the AD7625. The PulSAR family comprises 15 devices with speed options ranging from 1 to 10 Msamples/s and a dynamic range of 16 to 18 bits.
UP THE SPECTRUM Developed for a new generation of wireless and radar receivers that will require high channel density with high performance, Texas Instruments’ 14-bit, 250-Msample/s ADS6149 and the buffered-input ADS61B49 were introduced in October. The ADS6149 provides more than 70-dB SNR and 80-dB SFDR for input frequencies from dc to 250 MHz. Yet at 250 Msamples/s, the ADS6149 consumes only 687 mW. At 150 Msamples/s, with dynamic power scaling, the device consumes as little as 490 mW.
The new ADCs are part of a family of 12- and 14-bit devices that operate at 210 and 250 Msamples/s and share a number of customizable features. A 1- to 6-dB programmable gain option allows system designers to optimize SNR, SFDR, and input swing based on the needs of their application.
For instance, designers can maximize SNR to enhance linearization effectiveness in digital pre-distortion solutions, while SFDR can be increased and input drive reduced to improve small-signal analysis in defense and radio receiver applications. To further enhance flexibility, the ADS61B49 and ADS61B29 ease analog front-end (AFE) design by incorporating a fully differential input buffer.
This buffer provides constant input impedance over input frequency and eliminates kickback from the ADC’s track-and-hold circuit to ensure consistent linearity of the signal. To provide a flexible digital interface, the ADS61xx family also features userselectable parallel CMOS or differential double-data-rate (DDR) low-voltage differential signaling (LVDS) output options.
FRESH FACES ON OLD STANDBYS Earlier in the year, Analog Devices took a new look at the venerable voltage-feedback op amp and fine-tuned it for lowpower consumption. With a –3-dB bandwidth of 850 MHz and a 2800-V/µs slew rate, the ADA4857 high-speed op amp consumes 5 mA at 10 V (with an operating voltage range of 5 to 10 V), less than half the power of similar voltage-feedback amps (Fig. 3).
It also offers a top-notch combination of performance specifications, 4.4-nV/vHz input noise, and –91-dBc distortion at 10 MHz, which are both substantially better than amps with the same bandwidth that use more power. There are single- and dual-channel versions in chip-scale and small-outline IC (SOIC) packaging. Sample-quantity pricing starts at $0.85 for the singles and $1.39 for the duals.
In instrumentation amplifiers, TI raised—or lowered—the power bar in July. Its INA333 zero-drift instrumentation amplifier not only offers lower quiescent current (75 µA) and input bias current (200 pA) than its competition, it also provides an excellent power-to-noise ratio and offset voltage/drift specs (25 µV and offset drift of 0.1 µV/°C). Operating at 1.8 V, it’s appealing in handheld applications as well.
TI’s zero-drift technology, used in the INA333, is based on a switched-capacitor notch filter that eliminates chopping noise. The result is an input voltage noise spec of 50 nV/vHz. Special filters have been integrated in series with the inputs of the INA333 to reduce radio-frequency (RF) interference. This can dramatically reduce susceptibility to RF-induced offset voltage variations, useful in applications that require dc stability, such as weigh scales. Pricing starts at $1.80.
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