National Semiconductor Launches Innovative Direct RF Sampling ADC to Enhance Wireless Architecture Performance

With the realization of excellent ADC performance at input frequencies up to 2.7 GHz
Significant reduction in board size and component count in 3G/4G base stations, military, and SDR applications

July 12, 2011 – National Semiconductor Korea (CEO: Choi Chung-won) announced today the launch of a family of Analog-to-Digital Converter (ADC) products that directly sample RF signals exceeding 2.7 GHz with the industry's first maximum third-order intermodulation distortion (IMD3) of -71 dBc and a maximum sampling rate of 3.6 GSPS (giga samples per second). A product demonstration video is available at http://www.national.com/rfadc .

The ADC12Dxx00RF family includes five 12-bit ADCs that system designers can use to eliminate various intermediate frequency (IF) downconversion stages, including amplifiers, mixers, and filters. Since a single ADC12Dxx00RF product replaces the entire wireless signal path subsystem, it significantly reduces BOM costs, board size, and weight in 3G/4G wireless base stations, microwave backhaul, military, and broadband software-based radio communication (SDR) applications.

Jon Baldwin, Marketing Director of National Semiconductor’s Fast Signal Path business unit, stated, “Wireless device designers are seeking new ways to increase wireless performance while reducing cost, size, and weight. While RF sampling ADC-based architectures offer these benefits, it has been believed that this technology would take a long time to realize.” He added, “However, National’s ADC12Dxx00RF family of ADCs supports the core technology enabling the development of direct RF-sampling wireless devices today by delivering maximum high-frequency dynamic range and industry-leading sampling.”

The compatible ADC12Dxx00RF family incorporates National's industry-leading GSPS ADC family, supporting an easy upgrade path from 500 MSPS (mega samples per second) to 3.6 GSPS.

• The ADC12D1800RF provides an interleaved single-channel sampling rate of up to 3.6 GSPS or a dual-channel rate of up to 1.8 GSPS (IMD3 of -64 dBc at 2.7 GHz). Further information is available at http://www.national.com/pf/DC/ADC12D1800RF.html .

• The ADC12D1600RF provides an interleaved single-channel sampling rate of up to 3.2 GSPS or a dual-channel rate of up to 1.6 GSPS (IMD3 of -70 dBc at 2.7 GHz). Detailed information is available at http://www.national.com/pf/DC/ADC12D1600RF.html .

• The ADC12D1000RF provides an interleaved single-channel sampling rate of up to 2.0 GSPS or a dual-channel rate of up to 1.0 GSPS (IMD3 of -69 dBc at 2.7 GHz). Further information is available at http://www.national.com/pf/DC/ADC12D1000RF.html .

• The ADC12D800RF provides an interleaved single-channel sampling rate of up to 1.6 GSPS or a dual-channel rate of up to 800 MSPS (IMD3 of -71 dBc at 2.7 GHz). Further information is available at http://www.national.com/pf/DC/ADC12D800RF.html .

• The ADC12D500RF provides an interleaved single-channel sampling rate of up to 1.0 GSPS or a dual-channel rate of up to 500 MSPS (IMD3 of -69 dBc at 2.7 GHz). Detailed information is available at http://www.national.com/pf/DC/ADC12D500RF.html .

Thanks to the excellent linearity of these direct RF-sampling ADCs across the entire frequency range, they are easy to replace with other components, enabling relaxed performance requirements, further cost reductions, and shorter design timelines. To implement a complete signal path solution, the ADC12Dxx00RF family of ADCs can be combined with one of National’s dual-channel, digitally controlled variable gain amplifier (DVGA) families, the LMH6554 fully differential amplifier and LMX2541 frequency synthesizer, or one of National’s LMK04800 clock jitter cleaner families.

Price and commercial viability
All five 12-bit RF-sampling ADCs currently on the market are supplied in pin-compatible 292-ball BGA packages with improved thermal performance. Information on pricing, samples, and evaluation boards can be found at http://www.national.com/rfadc#products .