Focus on A/D converters: Parts boost ac performance, tap less power

The latest analog-to-digital converters from Analog Devices, Atmel, Linear Technology, Maxim Integrated Products, National Semiconductor and Texas
Instruments provide stronger ac performance, lower power consumption and smaller packages, all while operating at faster rates.

Most designers look at ac performance and power consumption when considering an A/D converter. Generally, one spec is more important than the other, depending on the application. Typically, if a converter touts strong ac performance, power consumption will be high, and vice versa.

Linear Technology Corp. (Milpitas, Calif.) has expanded its low-power, high-speed A/D converter offering with six new devices. The showstopper of the pack, aimed at cellular basestations, is a 125-megasample/second 14-bitter, the LTC2255, that boasts strong ac performance (72.1-dB signal-to-noise ratio and 85-dB spurious-free dynamic range at 70 MHz) and extremely low power (395 mW). While there may be competing devices with stronger ac performance, LTC says the LTC2255 offers the lowest power (about half of competing devices) at its performance level.

Click here too see more details on LTC’s LTC2255 at eeProductCenter.

Texas Instruments Inc's. 13-bit A/D converters feature 68-dB SNR and 79-dB SFDR at 210 Msamples/s and an input frequency of 230 MHz. The dynamic performance, achieved via TI's high-speed BiCom-III complementary
bipolar silicon germanium process, improves receiver performance in software-defined radios as well as basestation power amplifier linearization systems, according to TI (Dallas).

Click here too see more details on TI’s 13-bit A/D converters at eeProductCenter.

See related TI diagram

Maxim Integrated Products Inc. (Sunnyvale, Calif.) has introduced one of the fastest 250-Msamples/s 12-bit A/D converters. The device achieves a 74-dBc SFDR
and a signal-to-noise ratio of 66 dB at 10 MHz. SNR is said to remain flat (within 2 dB) for input tones up to 300 MHz.

The MAX1215 is intended for designers who need to implement higher-order power amplifier predistortion; the 250-Msample/s update rate allows them to sample
wider bandwidths with greater dynamic range than could have been sampled before, the company said.

Click here too see more details on Maxim’s MAX1215 at eeProductCenter.

 See related Maxim image

Analog Devices Inc. (Norwood, Mass.) launched a 12-bit monolithic A/D converter that is said to consume 40 percent less power than comparable devices —
190 mW at 65 Msamples/s, 135 mW at 40 Msamples/s and 90 mW at 20 Msamples/s — allowing for a higher channel count and simplified signal path to portable 12-bit systems.

Click here too see more details on ADI’s 12-bit A/D converter at eeProductCenter.

Atmel Corp. (San Jose, Calif.) has developed a fast 10-bit A/D converter with a clock frequency of 2.2 Gsamples/s. The AT84AS008GL, the latest in Atmel's family of gigahertz 10-bit data converters, provides a new level of linear performance over first and second Nyquist zones while reducing power consumption and
improving frequency spectral response, according to the company. This device provides a full 8 effective number of bits at 1.7 Gsamples/s in first Nyquist for high-speed digitization applications such as broadband test and measurement equipment, high-speed data acquisition, telecommunications and defense.

Click here too see more details on Atmel’s AT84AS008GL converter at eeProductCenter.

National Semiconductor Corp. has 10- and 12-bit A/D converters that are said to offer guaranteed performance across three speed ranges between 50 ksamples/s and 1 Msample/s.

The 12-bit, two- and four-channel A/D converters, for example, are said to provide no missing codes to 12 bits, ±1-least-significant-bit maximum integral
nonlinearity, ±1-LSB maximum differential nonlinearity and 71-dB minimum SNR. Power consumption is as low as 1.9 mW at 3 V, the company said.

Click here too see more details on National’s converters at eeProductCenter.

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