National Semiconductor Introduces Direct RF-Sampling ADCs at Input Frequencies up to 2.7 GHz

National Semiconductor introduced a family of analog-to-digital converters (ADCs) that are the industry’s first to directly sample RF signals beyond 2.7 GHz, with third-order intermodulation distortion (IMD3) up to -71 dBc and sampling at up to 3.6 Giga-samples per second (GSPS).
The ADC12Dxx00RF family includes five 12-bit ADCs that enable system designers to eliminate multiple intermediate frequency (IF) down-conversion stages including amplifiers, mixers and filters. A single ADC12Dxx00RF replaces entire radio signal path subsystems, drastically reducing bill of materials (BOM) cost, board size and weight in 3G/4G wireless basestations as well as microwave backhaul, military and wideband software-defined radio (SDR) applications.

The footprint-compatible ADC12Dxx00RF ADCs join National’s industry-leading GSPS ADC family, allowing an easy upgrade path from 500 Mega-samples per second (MSPS) to 3.6 GSPS:

• The ADC12D1800RF provides interleaved single-channel sampling rates up to 3.6 GSPS, or dual-channel rates up to 1.8 GSPS, with IMD3 of -64 dBc at 2.7 GHz.
• The ADC12D1600RF provides interleaved single-channel sampling rates up to 3.2 GSPS, or dual-channel rates up to 1.6 GSPS, with IMD3 of -70 dBc at 2.7 GHz.
• The ADC12D1000RF provides interleaved single-channel sampling rates up to 2.0 GSPS, or dual-channel rates up to 1.0 GSPS, with IMD3 of -69 dBc at 2.7 GHz.
• The ADC12D800RF provides interleaved single-channel sampling rates up to 1.6 GSPS, or dual-channel rates up to 800 MSPS, with IMD3 of -71 dBc at 2.7 GHz.
• The ADC12D500RF provides interleaved single-channel sampling rates up to 1.0 GSPS, or dual-channel rates up to 500 MSPS, with IMD3 of -69 dBc at 2.7 GHz.

The excellent linearity of these direct RF-sampling ADCs across all frequencies allows more system margin to be shifted to other components, easing their performance requirements and providing additional cost and design time savings. To form a complete signal path solution, the ADC12Dxx00RF ADC can be teamed with one of National’s dual-channel, digitally-controlled variable gain amplifiers (DVGA) or the LMH6554 fully differential amplifier, and LMX2541 frequency synthesizer or one of National’s LMK04800 clock jitter cleaners.

Available now, all five 12-bit RF-sampling ADCs are offered in pin-compatible, thermally-enhanced 292-ball BGA packages.

ADC12Dxx00RF – Family of Direct RF-Sampling ADCs
(Photo from National Semiconductor Website)

More information about Direct RF-Sampling ADCs can be found at National Semiconductor Website