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12bit ADC achieves 3.6GSps sampling speed

Posted: 28 May 2010 ?? ?Print Version ?Bookmark and Share

Keywords:ADC? software-defined radio? converter?

ADC12D1800 ADC

National Semiconductor Corp. has launched what it claims is the fastest 12bit ADC at 3.6GSps, 3.6x faster than any other available 12bit device. The ADC's dynamic performance of -147dBm/Hz noise floor, 52dB noise power ratio (NPR) and -61dBFS intermodulation distortion (IMD) enables a new generation of software-defined radio (SDR) architectures and applications.

In addition to the ADC12D1800, National introduced two other members of its ultrahigh-speed ADC family: the ADC12D1600 with sampling speed up to 3.2GSps and the ADC12D1000 with performance up to 2.0 GSPS. All three PowerWise ADCs target wideband SDRs including radar, communications, multichannel STB, signal intelligence and light detecting and ranging (LIDAR) applications.

Entirely new SDR architectures can be realized with National's ADC12D1x00 family due to its ability to accurately receive modulated, band-limited signals within a large bandwidth. For example, in military radar systems, a single ADC12D1X00 combined with a digital down-converter can replace multiple mixers, filters, amplifiers and local oscillator stages used in traditional heterodyne double- or triple-conversion radio implementations.

In next-generation multi-channel STB applications, one ADC12D1X00 can replace all of the STB's tuners. Shifting such architectures to an SDR implementation dramatically reduces board area, power consumption, and cost, while significantly improving system flexibility.

Since this new class of SDRs requires the ADC to sample wide-bandwidth signals, a new set of metrics such as noise-floor, NPR and IMD provide the best measure of a system's capability to extract narrowband information from a wideband spectrum. This is in stark contrast to traditional ADC specificationsSNR, spurious-free dynamic range (SFDR), and effective number of bits (ENOB)which focuses on single-tone performance in the Nyquist bandwidth and do not provide the best gauge of a system's overall capability.

National's 12bit ADCs are supplied in a leaded or lead-free, 292-ball, thermally enhanced BGA package, and are pin-compatible with the ADC10D1000 and ADC10D1500 ADCs. The 12bit ADCs run off a 1.9V single supply and consist of two channels that can operate interleaved or as independent channels. They include circuitry for multi-chip synchronization, programmable gain and offset adjustment per channel. The internal track-and-hold amplifier and extended self-calibration scheme enable a very flat response of all dynamic parameters for input frequencies exceeding 2GHz, while providing an exceptionally low 10-18 code error rate.

The ADC12D1800 provides sampling rates up to 3.6GSps, or dual-channel rates up to 1.8GSps. In addition to excellent noise floor, NPR and IMD performance, the ADC12D1800 offers 57.8 dB SNR, 67dBc SFDR and 9.2 ENOB at 125MHz. The energy-efficient design consumes only 2.05W per channel.

The ADC12D1600 delivers single-channel sampling rates up to 3.2GSps, or dual-channel rates up to 1.6GSps. It features a -147.5dBm/Hz noise floor, 52dB NPR and -63dBFS IMD. The ADC12D1600 consumes 1.9W per channel and offers 58.6dB SNR, 68dBc SFDR and 9.3 ENOB at 125MHz.

The ADC12D1000 provides single-channel sampling rates up to 2GSps, or dual-channel rates up to 1GSps. It features a -147.5dBm/Hz noise floor, 52dB NPR and -66dBFS IMD. The ADC12D1000 consumes 1.7W per channel and offers 59.1dB SNR, 70.5dBc SFDR and 9.5 ENOB at 125MHz.

A space-qualified version of the ADC12D1x00 will be supplied in a hermetic 376 CCGA package that meets radiation levels of 120MeV for single event latch-up and a total ionizing dose of 100 Krads (Si). The device is pin-compatible with the ADC10D1000QML 10bit ADC.

All three ADCs are sampling now, with production quantities available in Q3. Non-flight prototyping units and evaluation boards in the CCGA package will be available in Q3.

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