AD6649 IF Diversity Receiver

The AD6649 is a mixed-signal intermediate frequency (IF) receiver consisting of dual 14-bit, 250 MSPS ADCs and a wideband digital downconverter (DDC) and a bypass-able sample rate converter (SRC). The AD6649 is designed to support communications applications where low cost, small size, wide bandwidth and versatility are desired. APPLICATIONS Integrated dual, 14-bit, 250 MSPS ADC. Integrated wideband decimation filter and 32-bit complex NCO. Fast overrange and threshold detect. Proprietary differential input maintains excellent SNR performance for input frequencies up to 300 MHz. SYNC input allows synchronization of multiple devices. 3-pin, 1.8V SPI port for register programming and register readback.

The dual ADC core features a multistage, differential pipelined architecture with integrated output error correction logic. Each ADC features wide bandwidth inputs supporting a variety of user-selectable input ranges. An integrated voltage reference eases design considerations. A duty cycle stabilizer is provided to compensate for variations in the ADC clock duty cycle, allowing the converters to maintain excellent performance.

ADC data outputs are internally connected directly to the digital downconverter (DDC) of the receiver. The digital receiver has two channels and provides processing flexibility. Each receive channel has four cascaded signal processing stages: a 32-bit frequency translator (numerically controlled oscillator (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 several functions that simplify the automatic gain control (AGC) function in the system receiver. The programmable threshold detector allows monitoring of the incoming signal power using the fast detect output bits of the ADC. If the input signal level exceeds the programmable threshold, the fast detect indicator goes high. Because this threshold indicator has low latency, the user can quickly turn down the system gain to avoid an overrange condition at the ADC input.

After digital processing, data is routed directly to the 14-bit output port. These outputs operate at 1.8 V LVDS signal levels.

The AD6649 receiver digitizes a wide spectrum of IF frequencies. Each receiver is designed for simultaneous reception of the main channel and the diversity channel. This IF sampling architecture greatly reduces component cost and complexity compared with traditional analog techniques or less integrated digital methods. In diversity applications the output data format is real due to the final NCO which shifts the output center frequency to fs/4.

Flexible power-down options allow significant power savings, when desired.

Programming for setup and control is accomplished using a 3-pin SPI-compatible serial interface.

The AD6649 is available in a 64-lead LFCSP and is specified over the industrial temperature range of −40°C to +85°C.

PRODUCT HIGHLIGHTS
  • Integrated dual, 14-bit, 250 MSPS ADC.
  • Integrated wideband decimation filter and 32-bit complex NCO.
  • Fast overrange and threshold detect.
  • Proprietary differential input maintains excellent SNR performance for input frequencies up to 300 MHz.
  • SYNC input allows synchronization of multiple devices.
  • 3-pin, 1.8V SPI port for register programming and register readback.
Features and Benefits
  • SNR = 73.0 dBFS in a 95 MHz BW at 185 MHz Ain and
    245.76 MSPS
  • SFDR = 85 dBc at 185 MHz Ain and 250 MSPS
  • -151.2 dBFS/Hz Input Noise @ 220 MHz, -1dBFS Ain and 250MSPS
  • Total Power consumption: 1W
  • 1.8 V analog and LVDS output supply operation
  • Integer 1-to-8 input clock divider (625Mhz maximum input)
  • Integrated dual-channel ADC
    -- Sample rates up to 250 MSPS
    -- IF sampling frequencies to 400 MHz
  • Integrated wideband digital downconverter (DDC)
    -- 32-bit complex, numerically controlled oscillator (NCO)
    -- Sample Rate Converter and FIR filter with two modes
    -- Real Output from an fs/4 output NCO
  • Fast detect bits for efficient AGC implementation
  • Energy-saving power-down modes
  • Decimated Interleaved ‘Real’ LVDS Data Outputs
    -- See datasheet for additional features
RF & Microwave
Communications
    AD6649 IBIS Model
    Data Sheets
    Documentnote
    AD6649: IF Diversity Receiver Data Sheet (Rev. C)PDF 1083 kB
    Application Notes
    Documentnote
    AN-878: High Speed ADC SPI Control Software (Rev. A)PDF 585 kB
    AN-905: Visual Analog Converter Evaluation Tool Version 1.0 User Manual (Rev. 0)PDF 2124 kB
    AN-835: Understanding High Speed ADC Testing and Evaluation (Rev. B)PDF 985 kB
    AN-501: Aperture Uncertainty and ADC System Performance (Rev. A)PDF 227 kB
    AN-282: Fundamentals of Sampled Data SystemsPDF 2131 kB
    AN-756: Sampled Systems and the Effects of Clock Phase Noise and Jitter (Rev. 0)PDF 291.7 K
    AN-827: A Resonant Approach to Interfacing Amplifiers to Switched-Capacitor ADCs (Rev. 0)PDF 203 kB
    AN-935: Designing an ADC Transformer-Coupled Front End (Rev. 0)PDF 363 kB
    AN-742: Frequency Domain Response of Switched-Capacitor ADCs (Rev. B)PDF 401 kB
    AN-345: Grounding for Low-and-High-Frequency CircuitsPDF 455 kB
    AN-586: LVDS Outputs for High Speed A/D Converters (Rev. 0)PDF 207 kB
    AN-1142: Techniques for High Speed ADC PCB Layout (Rev. 0)PDF 392 kB
    AN-737: How ADIsimADC Models an ADC (Rev. B)PDF 373 kB
    AN-807: Multicarrier WCDMA Feasibility (Rev. 0)PDF 969 kB
    AN-808: Multicarrier CDMA2000 Feasibility (Rev. 0)PDF 1535 kB
    AN-851: A WiMax Double Downconversion IF Sampling Receiver Design (Rev. 0)PDF 262 kB
    AN-741: Little Known Characteristics of Phase Noise (Rev. 0)PDF 1679 kB
    User Guides
    Documentnote
    UG-293: Evaluating the AD9643/AD9613/AD6649/AD6643 Analog-to-Digital ConvertersPDF 2740 kB
    Order Information
    Part NumberPackagePacking QtyTemp RangePrice 100-499Price 1000+RoHS
    AD6649BCPZ Production64 ld LFCSP (9x9mm, 6.20mm exposed pad)OTH 260-40 to 85C9883.3Y
    AD6649BCPZRL7 Production64 ld LFCSP (9x9mm, 6.20mm exposed pad)REEL 750-40 to 85C9883.3Y
    Evaluation Boards
    Part NumberDescriptionPriceRoHS
    AD6649EBZEvaluation Board300Y
    AD9643-170EBZEvaluation Board300Y
    AD9643-210EBZEvaluation Board300Y
    AD9643-250EBZEvaluation Board300Y
    AD6649: IF Diversity Receiver Data Sheet (Rev. C) ad6649
    AD6649: 中频分集接收机 (Rev. A) ad6649
    AD6649BCPZ (All Speed Grades) ad6649
    AN-878: High Speed ADC SPI Control Software (Rev. A) ad6655
    AN-905: Visual Analog Converter Evaluation Tool Version 1.0 User Manual (Rev. 0) ad9220
    AN-835: Understanding High Speed ADC Testing and Evaluation (Rev. B) ad9220
    AN-501: Aperture Uncertainty and ADC System Performance (Rev. A) ad9220
    AN-282: Fundamentals of Sampled Data Systems ad1674
    AN-756: Sampled Systems and the Effects of Clock Phase Noise and Jitter (Rev. 0) ad9220
    AN-827: A Resonant Approach to Interfacing Amplifiers to Switched-Capacitor ADCs (Rev. 0) ad6655
    AN-935: Designing an ADC Transformer-Coupled Front End (Rev. 0) ad9220
    AN-742: Frequency Domain Response of Switched-Capacitor ADCs (Rev. B) ad7476
    AN-345: Grounding for Low-and-High-Frequency Circuits ad9220
    AN-586: LVDS Outputs for High Speed A/D Converters (Rev. 0) ad6642
    AN-835: 高速ADC测试和评估 (Rev. 0) ad9510
    AN-1142: 高速ADC PCB布局布线技巧 (Rev. 0) ad6655
    AN-1142: Techniques for High Speed ADC PCB Layout (Rev. 0) ad6655
    AN-878: 高速ADC SPI控制软件[中文版] (Rev. A) ad6655
    AN-282: 采样数据系统基本原理[中文版] (Rev. A) ad75019
    AN-737: 如何用ADIsimADC完成ADC建模 (Rev. B) ad6642
    AN-737: How ADIsimADC Models an ADC (Rev. B) ad9220
    AN-807: 多载波WCDMA的可行性 (Rev. 0) adf4106
    AN-807: Multicarrier WCDMA Feasibility (Rev. 0) ad6655
    AN-808: Multicarrier CDMA2000 Feasibility (Rev. 0) ad9863
    AN-827: 放大器与开关电容ADC接口的匹配方法[中文版] (Rev. 0) ad8351
    AN-905: VisualAnalog™转换器评估工具1.0版用户手册 (Rev. 0) ad6655
    AN-935: ADC变压器耦合前端设计[中文版] (Rev. 0) ad6655
    AN-586: 高速模数转换器的LVDS数据输出[中文版] (Rev. 0) ad6642
    AN-851: 一种WiMax双下变频IF采样接收机设计方案[中文版] (Rev. 0) ad9540
    AN-851: A WiMax Double Downconversion IF Sampling Receiver Design (Rev. 0) ad9856
    AN-345: 低频和高频电路接地 ad9540
    AN-756: 系统采样以及时钟相位噪声和抖动的影响[中文版] (Rev. 0) ad9540
    AN-501: 孔径不确定度与ADC系统性能[中文版] (Rev. A) ad9540
    AN-741: Little Known Characteristics of Phase Noise (Rev. 0) ad9221
    AN-741: 鲜为人知的相位噪声特性 ad9540
    UG-293: Evaluating the AD9643/AD9613/AD6649/AD6643 Analog-to-Digital Converters ad6643
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