原标题：ADI AD9652双路16位310MSPS模数转换(ADC)方案

　　ADI公司的AD9652是双路16位取样速率高达310MSPS的模数转换器(ADC),双路ADC核具有多级流水线架构和输出误差修正逻辑,输入频率范围高达465MHz,极低的噪音-157.6dBFS,SFDR超过85dBFS,通路间隔离/串扰90dB,主要用在军用雷达和通信,多模式数字接收器(3G或4G), 测试测量和智能天线系统.本文介绍了AD9652产品亮点和主要特性,功能框图,以及评估板AD-fmcomms6-EBZ主要特性,主要元件分布图,电路图和PCB元件分布图.

　　The AD9652 is a dual, 16-bit analog-to-digital converter (ADC) with sampling speeds of up to 310 MSPS. It is designed to support demanding, high speed signal processing applications that require exceptional dynamic range over a wide input frequency range (up to 465 MHz). Its exceptional low noise floor of −157.6 dBFS and large signal spurious-free dynamic range (SFDR) performance (exceeding 85 dBFS, typical) allows low level signals to be resolved in the presence of large signals.

　　The dual ADC cores feature a multistage, pipelined architecture with integrated output error correction logic. A high performance on-chip buffer and internal voltage reference simplify the inter-face to external driving circuitry while preserving the exceptional performance of the ADC.

　　The AD9652 can support input clock frequencies of up to 1.24 GHz with a 1, 2, 4, and 8 integer clock divider used to generate the ADC sample clock. A duty cycle stabilizer is provided to compensate for variations in the ADC clock duty cycle. The 16-bit output data (with an overrange bit) from each ADC is interleaved onto a single LVDS output port along with a double data rate (DDR) clock. Programming for setup and control are accomplished using a 3-wire SPI-compatible serial interface.

　　The AD9652 is available in a 144-ball CSP_BGA and is specified over the industrial temperature range of −40°C to +85°C. This product is protected by pending U.S. patents.

　　AD9652产品亮点:

　　1. Integrated dual, 16-bit, 310 MSPS ADCs.

　　2. On-chip buffer simplifies ADC driver interface.

　　3. Operation from 3.3 V and 1.8 V supplies and a separate digital output driver supply accommodating LVDS outputs.

　　4. Proprietary differential input maintains excellent signal-to-noise ratio (SNR) performance for input frequencies of up to 485 MHz.

　　5. SYNC input allows synchronization of multiple devices.

　　6. Three-wire, 3.3 V or 1.8 V SPI port for register programming and readback.

　　AD9652主要特性:

　　High dynamic range

　　SNR = 75.0 dBFS at 70 MHz (AIN = −1 dBFS)

　　SFDR = 87 dBc at 70 MHz (AIN = −1 dBFS)

　　Noise spectral density (NSD) = −156.7 dBFS/Hz input noise at −1 dBFS at 70 MHz

　　NSD = −157.6 dBFS/Hz for small signal at −7dBFS at 70 MHz

　　90 dB channel isolation/crosstalk

　　On-chip dithering (improves small signal linearity)

　　Excellent IF sampling performance

　　SNR = 73.7 dBFS at 170 MHz (AIN = −1 dBFS)

　　SFDR = 85 dBc at 170 MHz (AIN = −1 dBFS)

　　Full power bandwidth of 465 MHz

　　On-chip 3.3 V buffer

　　Programmable input span of 2 V p-p to 2.5 V p-p (default)

　　Differential clock input receiver with 1, 2, 4, and 8 integer inputs (clock divider input accepts up to 1.24 GHz)

　　Internal ADC clock duty cycle stabilizer

　　SYNC input allows multichip synchronization

　　Total power consumption: 2.16 W

　　3.3 V and 1.8 V supply voltages

　　DDR LVDS (ANSI-644 levels) outputs

　　Serial port control

　　Energy saving power-down modes

　　AD9652应用:

　　Military radar and communications

　　Multimode digital receivers (3G or 4G)

　　Test and instrumentation

　　Smart antenna systems

　　图1. AD9652功能框图

　　评估板AD-FMCOMMS6-EBZ

　　The AD-FMCOMMS6-EBZ eval board is a 400MHz to 4.4GHz receiver based on the AD9652 dual 16bit analog to digital converter, the ADL5566 High Dynamic Range RF/IF Dual Differential Amplifier and the ADL5380 quadrature demodulator. This is an I and Q demodulation approach to direct convert (also known as a homodyne or zero IF) receiver architecture. Direct conversion radios perform just one frequency translation compared to a super-heterodyne receiver that can perform several frequency translations. One frequency translation is advantageous because it • Reduces receiver complexity and the number of stages needed, increasing performance and reducing power consumption • Avoids image rejection issues and unwanted mixing. This topology will provide image rejection and early implementation of the differential signal environment. There is an amplification stage to maintain the full-scale input to the ACD. The local oscillator and ADC clock are on board and share the same reference signal prevent smearing. The form factor is VITA57 compliant and all of the DC power is routed from the data capture board through an FMC connector. This evaluation board demonstrates a high performance receiver signal chain aimed at military and commercial radar using “commercial off the shelf” (COTS) components. The overall circuit has a bandwidth of 220MHz with a pass band flatness of +/_ 1.0 dB. The SNR and SFDR measured at an IF of 145MHz are 64dB and 75dBc, respectively.

　　The AD-FMCOMMS6-EBZ evaluation board is a 400MHz to 4.4GHz receiver based on the AD9652 dual 16-bit analog to digital converter (ADC), the ADL5566 High Dynamic Range RF/IF Dual Differential Amplifier and the ADL5380 quadrature demodulator. This is an I and Q demodulation approach to direct convert (also known as a homodyne or zero IF) receiver architecture. This topology will provide image rejection and early implementation of the differential signal environment. There is an amplification stage to maintain the full-scale input to the ADC. The local oscillator and ADC clock are on board and share the same reference signal to prevent smearing. The form factor is VITA57 compliant and all of the DC power is routed from the data capture board through an FMC connector. This evaluation board demonstrates a high performance receiver signal chain aimed at military and commercial radar using "commercial off the shelf" (COTS) components. The overall circuit has a bandwidth of 220MHz with a pass band flatness of +/_ 1.0 dB. The SNR and SFDR measured at an IF of 145MHz are 64dB and 75dBc, respectively.

　　评估板AD-FMCOMMS6-EBZ主要特性:

　　RFin: 100MHz to 4GHz

　　IF: 10-155MHz

　　SNR: 68dB

　　SFDR: 78dB

　　RF input frequency range

　　- ADL5380: 400MHZ – 6 GHz Demod

　　- Supports UHF through S-bands and some C-band

　　AD9652: 16-bit, 310MSPS Dual ADC

　　- 74dB SNR across 1st Nyquist Zone

　　- 96dB SFDR

　　- 155dBFS/Hz noise floor

　　Integrated LO and on-board Clock with system reference and fanout

　　Amplifier and Filtering Options on-board

　　- ADL5566 Amp provides full-scale ADC Input

　　- AAF remove unwanted wideband noise

　　I/Q Demodulation

　　- Image rejection

　　- Low LO to RF leakage

　　评估板AD-FMCOMMS6-EBZ应用:

　　Military radar and communications

　　Reduced Size Weight and Power (SWaP)

　　Basestations

　　Handsets

　　Broadband instrumentation

　　Portable instrumentation

　　图2. 评估板AD-FMCOMMS6-EBZ外形图

　　图3. 评估板AD-FMCOMMS6-EBZ元件分布图

　　评估板AD-FMCOMMS6-EBZ包括:

　　AD9652 two 16-bit ADC with sampling speeds of up to 310 MSPS

　　ADL5380, a broadband quadrature I-Q demodulator that covers an RF/IF input frequency range from 400 MHz to 6 GHz.

　　ADL5566 a high performance, dual differential amplifier optimized for IF and dc applications.

　　ADP2370 high efficiency, low quiescent current, 800 mA buck (step-down) dc-to-dc converters in small 8-lead, 3 mm × 3 mm LFCSP (QFN) packages.

　　AD9517-4 provides a multi-output clock distribution function with subpicosecond jitter performance, along with an on-chip PLL and VCO.

　　ADF4351 allows implementation of fractional-N or integer-N phase-locked loop (PLL) frequency synthesizers if used with an external loop filter and external reference frequency.

　　ADM7150 is a low dropout linear regulator that operates from 4.5 V to 16 V and provides up to 800 mA of output current.

　　图 评估板AD-FMCOMMS6-EBZ电路图(1)