AD6649EBZ IF diversity receiver
The AD6649 is a mixed-signal intermediate frequency (IF) receiver with dual 14-bit, 250 MSPS ADCs, wideband digital downconverters (DDCs), and bypassable sample rate converters (SRCs) designed to provide a solution for low cost, small size, wide bandwidth, versatile communication applications.
This dual ADC uses a multistage, differential pipelined architecture with integrated output error correction logic. Each ADC has wide bandwidth inputs that support a variety of user-selectable input ranges. An integrated reference simplifies design. A duty cycle stabilizer can be used to compensate for fluctuations in the ADC clock duty cycle, allowing the converter to maintain excellent performance.
The ADC data output is internally connected directly to the receiver's digital downconverter (DDC). The dual-channel digital receiver has flexible processing capabilities. Each receive channel has four cascaded signal processing stages: a 32-bit frequency converter (digitally controlled oscillator, or NCO), an optional sample rate converter, a fixed FIR filter, and an fS/4 fixed frequency NCO.
In addition to the receiver DDC, the AD6649 has additional features that simplify automatic gain control (AGC) of the system receiver. Using the ADC's fast sense output bits, a programmable threshold detector monitors the input signal power. If the input signal level exceeds a programmable threshold, the quick detect indicator goes high. The very low latency of this threshold indicator allows the user to quickly lower the system gain to avoid overrange at the ADC input.
After digital processing, data can be routed directly to 14-bit output ports, which operate at a 1.8 V LVDS signal level.
AD6649ReceiverAbility to digitize a wide IF spectrum. Each receiver is designed to receive signals from both the main and diversity channels. This IF sampling architecture significantly reduces the cost and complexity of the device compared to traditional analog techniques or less integrated digital methods. In diversity applications, the output data format is real because the final NCO shifts the output center frequency to fs/4.
Flexible shutdown options can significantly reduce power consumption when needed.
Setup and control programming can be accomplished using a 3-wire SPI-compatible serial interface.
The AD6649 is available in a 64-lead LFCSP package and is specified over the industrial temperature range of −40°C to +85°C.
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- correspondence
- Diversity radio system
- Multi-Mode Digital Receiver (3G)
TD-SCDMA、WiMax、WCDMA
CDMA2000、GSM、EDGE、LTE
- Universal software defined radio
- Broadband data applications
Product features
- Integrated dual, 14-bit, 250 MSPS ADC.
- Integrated wideband decimation filter and 32-bit complex NCO.
- Fast overrange and threshold detection.
- The patented differential inputs maintain excellent signal-to-noise ratio (SNR) performance at input frequencies up to 300 MHz.
- The SYNC input enables synchronization between multiple devices.
- A 3-wire, 1.8V SPI port is available for register programming and register readback.