16-Bit, 10 MHz Bandwidth, 30 MSPS to 160 MSPS Continuous Time Sigma-Delta ADC

The AD9261 is a 16-bit analog-to-digital converter (ADC) based on a continuous time sigma-delta (Σ-Δ) architecture that achieves 86 dB of dynamic range over a 10 MHz input bandwidth. The integrated features and characteristics unique to the continuous time Σ-Δ architecture significantly simplify its use and minimize the need for external components.

The AD9261 has a resistive input impedance that significantly relaxes the requirements of the driver amplifier. In addition, a 32× oversampled 5th-order continuous time loop filter significantly attenuates out of band signals and aliases, reducing the need for external filters at the input.

An external clock input or the integrated integer-N PLL provides the 640 MHz internal clock needed for the oversampled continuous time Σ-Δ modulator. On-chip decimation filters and sample rate converters reduce the modulator data rate from 640 MSPS to a user-defined output data rate between 30 MSPS to 160 MSPS, enabling a more efficient and direct interface.

The digital output data is presented in offset binary, Gray code, or twos complement format. A data clock output (DCO) is provided to ensure proper timing with the receiving logic.

The AD9261 operates on a 1.8 V analog supply and a 1.8 V to 3.3 V digital supply, consuming 375 mW. The AD9261 is available in a 48-lead LFCSP and is specified over the industrial temperature range (−40°C to +85°C).

Product Highlights

* Continuous time Σ-Δ architecture efficiently achieves high dynamic range and wide bandwidth.

* Passive input structure reduces or eliminates the requirements for a driver amplifier.

* An oversampling ratio of 32× and high order loop filter provide excellent alias rejection reducing or eliminating the need for antialiasing filters.

* An integrated decimation filter, sample rate converter, PLL clock multiplier, and voltage reference provide ease of use.

* Operates from a single 1.8 V analog power supply and 1.8 V to 3.3 V output supply.

* A standard serial port interface (SPI) supports various product features and functions.

Applications

* Data Acquisition

* Automated Test Equipment

* Instrumentation

* Medical Imaging

* SNR: 83 dB (85 dBFS) to 10 MHz input

* SFDR: 87 dBc to 10 MHz input

* Noise figure: 15 dB

* Input impedance: 1 kΩ

* Power: 340 mW

* 1.8 V analog supply operation

* 1.8 V to 3.3 V output supply

* Selectable bandwidth 2.5 MHz/5 MHz/10 MHz