10 MHz Bandwidth, 640 MSPS Dual Continuous Time Sigma-Delta Modulator
The AD9267 has a resistive input impedance that significantly relaxes the requirements of the driver amplifier. In addition, a 32× oversampled fifth-order continuous time loop filter attenuates out-of-band signals and aliases, reducing the need for external filters at the input. The low noise figure of 15 dB relaxes the linearity requirements of the front-end signal chain components, and the high dynamic range reduces the need for an automatic gain control (AGC) loop.
A differential input clock controls all internal conversion cycles. An external clock input or the integrated integer-N PLL provides the 640 MHz internal clock needed for the oversampled conti- nuous time Σ-Δ modulator. The digital output data is presented as 4-bit, LVDS at 640 MSPS in twos complement format. A data clock output (DCO) is provided to ensure proper latch timing with receiving logic. Additional digital signal processing may be required on the 4-bit modulator output to remove the out-of-band noise and to reduce the sample rate.
The AD9267 operates on a 1.8 V power supply, consuming 416 mW. The AD9267 is available in a 64-lead LFCSP and is specified over the industrial temperature range (−40°C to +85°C).
- Continuous time Σ-Δ architecture efficiently achieves high dynamic range and wide bandwidth.
- Passive input structure reduces or eliminates the require- ments 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.
- Operates from a single 1.8 V power supply.
- A standard serial port interface (SPI) supports various product features and functions.
- Features a low pin count, high speed LVDS interface with data output clock.
- Baseband quadrature receivers: CDMA2000, W-CDMA, multicarrier GSM/EDGE, 802.16x, and LTE
- Quadrature sampling instrumentation
This designates products ADI does not recommend broadly for new designs.
The AD9267 is a dual continuous time Σ-Δ modulator with −88 dBc of dynamic range over 10 MHz real or 20 MHz complex bandwidth. The combination of high dynamic range, wide bandwidth, and characteristics unique to the continuous time Σ-Δ modulator architecture makes the AD9267 an ideal solution for wireless communication systems.
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