Texas Instruments Incorporated announced a pair of dual-channel, 12-bit analog-to-digital converters (ADC) from the company's Burr-Brown product line. These high-performance data converters operate at 50Msps (ADS2807) and 32Msps (ADS2806) making them ideal for multi-channel communications and medical imaging applications such as base stations and ultrasound systems.

"The ADS2806 and ADS2807 extend TI's family of high-performance, high-speed analog solutions by increasing our presence in applications which benefit from a dual-channel, high-speed ADC solution," said Ed Fullman, product marketing manager of Burr-Brown High-Speed Products from TI. "Furthermore, when combined with our existing high-speed driver op amps, TI can offer the customer a complete solution for undersampling and baseband applications."

The ADS2806 and ADS2807 include a high-bandwidth track-and-hold that gives excellent spurious performance up to and beyond the Nyquist rate. The differential nature of this track-and-hold and ADC circuitry minimizes even-order harmonics and gives excellent common-mode noise immunity. The ADS2806 features 66dB SNR (signal-to-noise ratio) and 73dB SFDR (spurious free dynamic range); the ADS2807 features 65dB SNR and 70dB SFDR.

Both converters allow for setting the full-scale range without any external reference circuitry. The internal reference can be disabled allowing low drive external references to be used for improved tracking in multi-channel systems. An over-range flag indicates when the input signal has exceeded the converter's full-scale range. This flag can also be used to reduce the gain of the front-end gain control circuitry. These devices provide dramatic flexibility by offering 2Vp-p and 3Vp-p input ranges and the ability to operate either differentially or single ended. Digital error correction techniques are employed to provide excellent differential linearity.

The majority of high bandwidth communications applications for ADCs require two channels. In recent years getting the performances wanted out of just one has been a development that has been impressive to watch and the prices have drifted downwards as more manufacturers have got into that business. Now we have a couple of duals with performances that are up with the best. An internal reference is included on each part.

The ADS2807 shows an analog input bandwidth of a typical 270 MHz with SFDRs in the low 70 dBFS range and SNRs in the upper 60s. The track-and-holds are differential and eliminate the even-order harmonics, although they can be operated single-ended if required. A critical spec in a dual such as this -- channel-to-channel crosstalk -- is at a healthy 85 dB. The aperture jitter is just 1.2 ps rms with an aperture delay time, and overvoltage recovery time of 2 ns. An indicator flag shows if an input signal exceeds the FS range of the converters.

These are 5-V parts with a quiescent of 116 mA. Because of the input, capacitive nature, special care must be used in driving them and TI offers a number of potential systems in the data sheets. Digital outputs are at CMOS levels.