Analog Angle Article

ADC pumps 12-bit results at 1 Gsps while buffered input yields smooth driving

Dallas, Texas—The ADS5400 analog/digital converter (ADC) from Texas Instruments targets high-speed, wideband applications with its 1-gigasample per second (Gsps) conversion rate at 12 bits resolution, along with superior dynamic-performance specifications. It includes a fully buffered analog input which isolates the on-board sample and hold's internal switching glitches to prevent disturbing the signal source, while also providing a high-impedance input, thus greatly simplifying drive requirements—no kick-back from the internal sample/hold (S/H), as well as easier active or passive matching—and maintaining overall analog-channel performance.

The converter features signal-to-noise ratio (SNR) of 59 dBFS and 75 dBc spurious-free dynamic range (SFDR) in first Nyquist, and 58 dBFS SNR and 70 dBc SFDR performance for intermediate frequencies (IFs) beyond 1000 MHz. It also sports 2.1 GHz input bandwidth, for wideband signals in oversampling and undersampling applications having 200 MHz (or wider) signal bandwidth. Multichannel applications can take advantage of the converter's adjustable fine gain, offset and phase, which eases the interleaving of two or more ADCs when developing a multi-GSPS digitizer, or balancing two ADCs in an I/Q receiver design.

The ADS5400 provides 57 dB SNR with 73 dBc SFDR at a 925-MHz IF
(Click on image to enlarge)

On the digital side, the ADS5400 provides user-selectable single- or dual-bus double data rate (DDR) low voltage differential signal (LVDS) outputs for flexibility in the trade-off between I/O speed and pin count. The monolithic converter is fabricated using TI's established, high-speed, proprietary BiCom3 complementary bipolar SiGe technology, and is specified over the full industrial temperature range (–40°C to 85°C).

A high-speed converter IC such as this one would not be complete without a demonstration/evaluation board and support, due to the high speeds, wide bandwidths, and fast data rates in its applications. TI offers an evaluation module is compatible with their TSW1200EVM digital capture card and software, for prototyping and evaluating the performance of high-speed ADCs with parallel or serialized LVDS outputs.—Bill Schweber

Packaging, price, and availability : The ADS5400 is available now. It comes in a thermally-enhanced, 100-pin TQFP (16 mm × 16 mm footprint) package with exposed thermal pad. It is priced at $775 in100-unit quantities.

For more information : contact Texas Instruments or see details at

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