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National Semiconductor Introduces Two New Low-Power High-Speed Analog to Digital Converters

Nationalıs 8-Bit 60MSPS ADC08L060 and 12-Bit Dual 40MSPS ADC12D040 are the Lowest-Power 8- and 12-Bit ADCs in the Industry

The manufacturer says . . .

ChipCenter's Paul O'Shea says . . .

National Semiconductor Corporation today announced the industryıs lowest-power 8-bit 60MSPS ADC and the lowest-power 5V dual 12-bit 40MSPS ADC. The ADC08L060 consumes only 39mW at 60MSPS while the 40MSPS two-channel ADC12D040 consumes only 650mW. Nationalıs ADC08L060 is well suited for digital communications, portable test equipment, camcorders and portable ultrasound imaging. The ADC12D040 is designed for medical ultrasound imaging, television broadcast cameras, wireless local loops and digital communications. ıNational provides the lowest-power high-speed ADCs on the market today to address the needs of portable ultrasound imaging, broadcast, and test equipment,ı said Suresh Ram, marketing manager for Nationalıs data conversion systems product group. ıNational is well-positioned to continue its growth in the high-speed market by meeting and exceeding customer expectations with innovative solutions.ı ADC08L060 National Semiconductorıs ADC08L060 consumes only 0.65mW/MSPS, while delivering the highest dynamic performance out to Nyquist, enabling its applicability in battery-powered, portable applications. The ADC08L060 features power consumption that scales with sample rate, providing the flexibility to use the part at any conversion rate between 10MSPS and 60MSPS while consuming power proportional to the speed of operation. The ADC08L060 has no clock duty cycle dependence from 5% - 91%, allowing it to be used in applications such as ultrasound imaging where beam-forming techniques may force the duty cycle of the ADCıs conversion clock to deviate substantially from 50%. ADC12D040 The ADC12D040 provides best-in-class dynamic specifications with 68dB signal-to-noise ratio (SNR) and 80dB spurious free dynamic range (SFDR). The ADC12D040ıs high SNR provides superior image quality in imaging applications. With an internal reference and selectable parallel 2ıs complement or binary outputs, the ADC12D040 provides a seamless interface to ASICs in ultrasound imaging systems. The dual feature of the ADC12D040 reduces board space and system power dissipation, particularly in ultrasound applications using 128 channels. Additionally, this device features close channel matching and virtually no cross talk. National also offers an evaluation board and software that facilitates quick bench trials and simplifies final circuit design. Using National's WaveVision software running under Microsoft Windows, designers can capture and display multiple waveform data from the ADC in graphical form from a menu-driven environment. The software can also perform Fast Fourier Transform (FFT) calculations on the data to measure the dynamic performance of the ADC, displaying Signal to Noise Ratio (SNR), Signal to Noise and Distortion (SINAD), Total Harmonic Distortion (THD), and Spurious Free Dynamic Range (SFDR) in addition to the spectral plot from the FFT. For more information on National Semiconductorıs data conversion products, visit http://www.national.com/appinfo/adc/.

National Semiconductor positioned these two analog-to-digital converters (ADCs) primarily for the ultrasound imaging market, but they will work well in other applications. For example, you could use them in a communications application like IQ baseband sampling for a wireless basestation. This is a good fit for an application such as ultrasound imaging because it doesnıt use the standard 50% duty cycle clock. Ultrasound users need to vary the clock in order to recreate an image and get better image quality so they need to move the clock edges around. Therefore, they need an ADC whose performance is not affected by clock edges moving around. Additionally, because it is a low power device it fits into portable ultrasound systems and works well with camcorder applications, as well as those that require an 8-bit operation and low power consumption. The ADC08L060 is an 8-bit 60MSPS ADC. It works from 10MHz to 60MHz sampling rates. The ADC12D040 is a dual, 12-bit 40MSPS ADC. The 12-bit ADC12D040 is a 5V part, the 8-bit ADC08L060 works from 2.7V to 3.6V. The 12-bit part offers a high signal-to-noise ratio (SNR) of about 68dB, which makes the image quality very good in high-end ultrasound imaging equipment. It typically goes into imaging systems that need 128 ADCs or as few as 64 and as many as 256 ADCs. In these applications the reference on the chip is critical. Some applications like to keep the reference external and some ultrasound systems like to use internal references that they calibrate. This part offers both - you can use the internal reference or you can drive it from an external reference. The SNR of the ADC08L060 is typically 48dB, which is good compared to the 46 and 47.5dB offered by the competition. Itıs important to know that National doesnıt play specmanship with this figure because they measure the 48-dB at 10.1MHz - the typical frequency used by the industry. The National Semi spec for SFDR ı spurious-free dynamic range ı is 80dB while others provide only 70dB. Obviously, companies want to show the data sheet information in a good light, but you really need to put the part in the system and consider a wide range of input frequencies, to consider larger amplitude signals. The National part can take a 4Vp-p differential input signal. Thatıs a large magnitude of differential that you can put in the part. When you subject it to real-time conditions you can look at the dynamic performance across the Nyquist ı half the sampling rate. For example, for a 40 MSPS part the Nyquist sample is 20MSPS. So after the Nyquist frequency the performance of the part starts degrading. Power consumption is also a significant spec for this product. For example, if you put 128 ADCs on a board you would have 128 chips X 600mW and that becomes important. The competition offers a similar part with 720 to 750 mW so when you multiply that by 128 the difference becomes significant. It enables the ultrasound equipment manufacturers to use equipment that doesnıt use extreme power. The 8-bit 60MSPS ADC08L060 operates from 10MHz to 60MHz sampling rates. It consumes 0.65mW per MSPS of operation. Importantly, the power consumption is scalable with the speed. So if you use the part at 10MSPS it will consume lower power than at 60 MSPS. Another key feature for the part is that it is not dependent on the clock duty cycle. So you can have a clock that has a duty cycle that ranges from 5% up to 91% and the part will still run. For the output, these ADCs use an internal reference with either a parallel 2ıs complement or binary output. The 2ıs complement would be especially attractive to communications engineers, while ultrasound users would like binary. National decided to add the internal reference because it just requires the addition of a small clock. National provides their WaveVision software when you order an evaluation board. It shows you all the typical measurements that an engineer using an ADC would need, such as effective number of bits, SNR, SFDR, FFTs. The ADC08L060 is available in a 24-pin TSSOP package and is priced at $3.00. The ADC12D040, sampling now, is available in a 64-pin TQFP package and is priced at $17.00. All prices are in 1000-unit quantities. Design Support Group, Tel: 800-272-9959; http://www.national.com/ Click for Product Brochures : ADC08L060 and the ADC12D040

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