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14-bit, 125-MSPS A/D converter Opens Up Path to Advanced Signal Processing

Utilizing its leading-edge high-performance analog design expertise, Texas Instruments Incorporated (TI) today announced a technology advancement with a 14-bit, 125-MSPS (mega samples per second) analog-to-digital converter (ADC). The unmatched performance at 125 MSPS allows increased system capabilities in advanced communications, test and measurement, medical, video and imaging applications, while the low total power dissipation (750 mW) improves system reliability and allows higher channel density.

The ADS5500, operating at 125 MSPS, features 70-dB SNR (signal-to-noise ratio) and 82-dB SFDR (spurious-free dynamic range) at 100-MHz input frequency. Equipment manufacturers can capitalize on the performance of the ADS5500 to achieve a wide range of benefits, such as improved receiver performance in wireless communications, higher quality imaging in video systems, extended signal analysis capabilities for test equipment, and more precise scans and lower magnetic field energy in medical Magnetic Resonance Imaging (MRI) equipment.

The low power dissipation reduces power supply requirements and the need for thermal management (cooling), resulting in smaller footprint and equipment size, and higher circuit density. The power savings also enables next-generation, high-performance portable wireless, test and measurement and video imaging systems.

“The ADS5500 combines speed, performance and power attributes unmatched in the data converter market and extends TI's technology leadership in the high-performance analog industry,” said Gregg Lowe, senior vice president of TI's high-performance analog business. “The device builds upon many recent data converter breakthroughs and is further evidence of the collaborative technology advancements TI has achieved through the Burr-Brown acquisition. The ADS5500 is one of several significant high-performance data converter announcements that TI will make over the next year.”

The performance of the ADS5500 allows wireless communications systems, such as base stations, to achieve higher receiver performance and handle more voice channels, thus allowing accurate reception of weaker, distant signals and reducing the number of analog signal chain components needed per base station. When combined with TI's GC5016 digital up/down converter, the ADS5500 allows oversampling and undersampling of the input IF signal to improve signal quality and reduce circuit complexity. The ADS5500 excels at processing high input frequencies, such as 190 MHz, for undersampling applications.

Test and measurement applications benefit from high SNR and high sampling rate to deliver more accurate signal analysis over a broader signal range. Examples of precision test and measurement applications are integrated circuit test equipment, production test equipment and laboratory instruments.

The high SNR and sample rate of the ADS5500 can enable medical equipment manufacturers to increase image quality of their MRI scans with lower magnetic fields, thus reducing shielding requirements. The higher sampling rate can also simplify the filter requirements of MRI systems.

Video and imaging applications, such as broadcast cameras, high-end professional scanners and video inspection, leverage high SNR for more precise images, while 125 MSPS simplifies analog filter design, reduces scan time and lowers system complexity.

The ADS5500 is sampling now, with volume production scheduled for 1Q 2004. The device comes in a 64-TQFP PowerPad package and is priced at $95.00 in 1,000 piece quantities (suggested resale pricing). Evaluation modules (EVMs) are also available.

Texas Instruments Incorporated, Semiconductor Group, SC-03242, Literature Response Center, P.O. Box 954, Santa Clara, CA 91380. Tel: 1-800-477-8924
TI web site

This ADS5500 pipeline A/D converter is a part that TI has been working on for a couple years. It will definitely make some competitors sit up and take notice. For starters, it's a CMOS converter and it has good performance with a signal-to-noise ratio (SNR) at 70 dB and a spurious-free dynamic range (SFDR) at 82 dB, and probably most significantly the power dissipation is a mere 750 mW.

Why CMOS? TI says its customers wanted a converter in CMOS, but only if it could provide the appropriate signal-to-noise performance and power dissipation levels to enable them to pack as many channels in their base stations as possible. Using CMOS also enabled TI to get the high-speed A/D and D/A converters, and even the digital down and digital up converters all on the same CMOS platform. The result is a triple threat product offering speed, performance and low power on one chip.

The 5500 uses a single 3.3-V supply and an internal reference with an option to use an external reference for the high-precision applications. The analog input is 2 V p-p, with a data ready output clock and has an input bandwidth of 700 MHz; so it supports high input frequencies for under sampling used in wireless applications.

Compared to the competition, this converter has about one-half the power dissipation as its nearest rival (as of today). It's also specified to run from -40C to +85C, which is important to the telecom users who need to pack more into the same space and not increase the power. TI achieved such a low power dissipation using its 180 nm CMOS process, even though conventional wisdom said you couldn't attain the right trade off between performance and speed in such a small process size in an analog device. TI says it was through aggressive design techniques that it overcame the shortcomings of higher leakage at 3.3V. Amazingly, TI says the limit for power and speed has not yet been attained for this process.

The TI converter hits the market at a good time since the world wide demand for pipelined converters is increasing. It's important because several markets will be enabled by the performance and low power of these pipelined converters. For example, the new wireless standards for cell phone base station applications and its need for increased system performance and higher processing speeds is driving the need for high-speed converters. These converters will also help capture the data that can be fed into digital signal processors.

Other applications include high-end imaging that requires high resolution and speed and leading edge test and measurement systems that need wide dynamic range, the highest level of resolution, and low power. Test companies want the low power because they have to cram more channels in less space, which means power and heat are a problem.

The medical applications include MRIs. TI says that as they introduce better A/D converters it directly impacts the medical equipment end user because they can get better image quality and maybe just as importantly they don't need as strong a magnetic field, so it's not as invasive to the patient. MRI equipment uses a very high magnetic field with RF coils and sends a magnetic waveform through your body so it's a safe way to scan. The magnetic waveform outputs very low level RF signals that are detected, amplified, and then converted to digital signals. The speed of the converter is used to over-sample and that helps improve the SNR. It's the SNR improvement that enables the user to reduce the magnetic field.

The 5500 will support multi carrier systems, with more voice channels through one A/D converter. That's great because many customers are looking for that as they push to design more cost-effective base stations. This converter also allows designers to remove mixer stages and that will give a higher dynamic range and sampling rate, and enable the combining of signals.

TI will have sample boards on Dec 1 as well as the EVM boards. This will help the customer take a valid look at the part. Production will take place in first quarter 2004.

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