高精度模数转换器的接口技术

为了保证高精度模数转换器的性能,在设计和使用高精度ADC的外围接口电路时应考虑到数据输出接口、基准电压模块、输入信号调理、电源管理、数字时序逻辑等多方面的因素,只有严格设计才能保证ADC的正常使用,并减小由于外围接口电路所带来的失调误差、增益误差等误差。本文结合具体实例,提出了高精度ADC的接口设计方案。     

EV8AQ160型ADC在2.5 Gsps双通道高速信号采集系统中的应用

针对某高速实时频谱仪中的高速模数转换器(ADC)的应用,基于信号采集系统硬件平台,介绍了一种最大采样率可达5 Gbps的高速8位A/D转换器EV8AQ160。该器件内部由4路并行的ADC构成,各路ADC可并行工作也可交错工作。详细描述了EV8AQ160在交错模式下的工作原理,介绍了其在某双通道高速信号采集系统中的应用,给出了EV8AQ160与Xilinx公司Virtex-6 FPGA的接口设计方案以及系统结构框图,并用ISE的在线逻辑分析仪(ChipScope Pro)测试了ADC性能。把ADC输出的数据存储在DDR3中,然后进行FFT变换,进而分析ADC的信噪比及有效位数,实测表明整体指标达到设计要求。     

基于JESD204B的射频信号高速采集系统设计

为了解决传统转换器传输接口传输速率低、抗干扰差、布局布线面积大等问题,设计了一种基于JESD204B的射频信号高速采集系统。系统对接收到的射频信号进行下变频处理,通过高速ADC对解调基带信号直接采样,采样后的数字基带信号通过自主设计的JESD204B接口逻辑传输至FPGA并缓存。测试结果表明,系统可实现1.0 Gsample/s采样率的直接采样,数据传输速率可达10 Gbit/s,且数据链路稳定可靠。     

USB2．0接口技术在数字广播接收领域中的应用

USB作为一种新型的接口技术，具有简单易用、速度快等特点而应用到与PC接口相关的众多领域。本将介绍USB技术及其高速USB2．0接口在数据广播接收领域中的应用、前景和展望，并简单说明基于USB2．0接口芯片的数字广播接收卡的结构。     

基于FPGA的CPCI和LVDS接口技术及应用

CPCI总线为不同应用的高速数字系统提供了一个通用、开放的平台,它充分发挥了PCI总线的高性能、低成本、通用操作系统等特点,而LVDS接口技术无疑也将成为解决高速数字系统数据传输的首选方案.提出了一种基于FPGA实现CPCI总线接口与LVDS接口的新方法,CPCI总线与自定义LVDS接口相结合,在不降低系统通用性的前提下,提高了系统实时并行处理能力.由于所有接口均由FPGA来实现,因此提高了系统的可重构性.     

FPGA中DCM工作原理及其在高速ADC电路中的应用

简述了Xilinx公司Virtex系列FPGA中数字时钟管理器(DCM)的工作原理,以及在高速ADC输出数据同步处理电路中的应用。给出采用DCM进行高速数据同步处理方法,数据同步时钟相位调节的方法和试验结论。     

基于FPGA的CPCl和LVDS接口技术及应用

CPCI总线为不同应用的高速数字系统提供了一个通用、开放的平台，它充分发挥了PCI总线的高性能、低成本、通用操作系统等特点，而LVDS接口技术无疑也将成为解决高速数字系统数据传输的首选方案。提出了一种基于FPGA实现CPCI总线接口与LVDS接口的新方法，CPCI总线与自定义LVDS接口相结合，在不降低系统通用性的前提下，提高了系统实时并行处理能力。由于所有接口均由FPGA来实现，因此提高了系统的可重构性。     

IEEE1394接口及其在全数字化制作网络中的应用

IEEE1394接口具有良好的物理特性和高速数据传输能力,非常适合数字视音频数据传输。通过IEEE1394创建高速局域网络,能够进行声音、图像信息的高质量的实时传送。分析IEEE1394接口技术,并结合实例介绍IEEE1394接口在中小电视台全数字化制作网络中的应用。     

IEEE1394接口及其在全数字化制作网络中的应用

IEEE1394接口具有良好的物理特性和高速数据传输能力,非常适合数字视音频数据传输.通过IEEE1394创建高速局域网络,能够进行声音、图像信息的高质量的实时传送.分析IEEE1394接口技术,并结合实例介绍IEEE1394接口在中小电视台全数字化制作网络中的应用.     

流水线ADC设计中的数字校准算法与实现

数字校准是高速高精度流水线ADC设计中的关键技术之一。文章提出了一种可通过校准控制生成测试信号,自动计算权重来对流水线ADC中电容失配进行误差补偿的技术。该技术能有效地减小增益有限、电荷注入等非理想因素的影响,使校准输出后的数据拥有更高的准确度,提高了系统的线性度。     

Cascaded Complex ADCs With Adaptive Digital Calibration for $I/Q$ Mismatch

A complex analog-to-digital converter (ADC) intended for digital intermediate frequency (IF) receiver applications digitizes analog signals at IFs with excellent power/bandwidth efficiency. However, it is vulnerable to mismatches between its in-phase and quadrature (I/Q) paths that can dramatically degrade its performance. The proposed solution mitigates I/Q mismatch effects using a complex sigma-delta (SigmaDelta) modulator cascaded with 9-bit pipeline converters in each of the I and Q paths. The quantization noise of the first stage complex modulator is eliminated using an adaptive scheme to calibrate finite-impulse response digital filters in the digital noise-cancellation logic block. Although low-pass SigmaDelta cascade ADCs are widely used because of their inherent stability and high-order noise shaping, the complex bandpass cascade architecture introduced herein maintains these advantages and doubles the noise shaping bandwidth. Digital calibration also reduces the effects of analog circuit limitations such as finite operational amplifier gain, which enables high performance and low power consumption with high-speed deep-submicrometer CMOS technology. Behavioral simulations of the complex SigmaDelta/pipeline cascade bandpass ADC using the adaptive digital calibration algorithm predict a signal-to-noise ratio (SNR) of 78 dB over a 20-MHz signal bandwidth at a sampling rate of 160 MHz in the presence of a 1% I/Q mismatch.     

光学Sigma-Delta模数转换器的研究进展

采用光学模数转换技术已经成为高转换速率、高比特精度模数转换器(ADC)的发展趋势.光学Sigma-Delta ADC作为一种光学ADC,具有转换精度高和模拟电路简单等显著优点.介绍了光学Sigma-Delta ADC的基本原理,详细阐述了几种典型的光学Sigma-Delta ADC的系统结构,对不同结构的光学Sigma-Delta ADC的优缺点进行了归纳总结.     

一种应用于流水线ADC的自适应后台校正技术

流水线模数转换器(Pipeline ADC)是一种应用广泛的模数转换器结构,可以同时实现高速和高精度性能。然而电路的非理想性严重制约着流水线ADC的性能。提出了一种自适应数字技术,通过使用低速但准确的ADC作为基准,与待校正的流水线ADC并联,并将两者的数字输出的差值送入数字自适应滤波器中进行处理,使流水线ADC的输出不断逼近低速但准确的ADC输出,从而达到数字校正的目的。仿真结果表明,这种方法可以有效去除包括电容失配、有限运放增益、运放失调在内的误差。     

下一代光传输系统中超高速ADC芯片性能测试方法

针对下一代光传输系统对模数转换器（ADC）高采样率、大带宽的要求,提出一种针对该类ADC动态性能的测试方法.通过分析光传输系统中ADC芯片的特点,解决了采样时钟无法直接测量,输出数据难以捕获,分辨率不易统计,插损非线性导致带宽测量偏差等问题,并将该方法应用于光传输、雷达、卫星等高数据率场景所用超高速ADC芯片的评测中.测试结果表明,该方法解决了最高采样率70GSPS带宽16GHz的超高速ADC测试的关键问题,基本满足下一代400Gbps光传输系统对ADC动态性能测试的要求.     

高性能A/D转换器校准技术研究进展

A/D转换器(ADC)的校准技术是提高高性能ADC转换精度的必要手段,它分为模拟校准技术和数字校准技术。数字校准技术较之模拟校准技术更为有效和更具灵活性。数字校准技术是在数字域进行错误代码计算,减轻了对模拟电路的精度要求。在主流制造工艺小尺寸化的趋势之下,许多创新的校准技术得到发展,并广泛应用于包括射频直接采样ADC在内的高速高精度ADC中。本文在分析最新的高速高精度ADC中采用的主要校准技术的基础上,重点研究了几种高采样率高精度ADC所采用的校准技术,侧重分析了数字校准技术。     

Superconductor analog-to-digital converters

Ultrafast switching speed, low power, natural quantization of magnetic flux, quantum accuracy, and low noise of cryogenic superconductor circuits enable fast and accurate data conversion between the analog and digital domains. Based on rapid single-flux quantum (RSFQ) logic, these integrated circuits are capable of achieving performance levels unattainable by any other technology. Two major classes of superconductor analog-to-digital converters (ADCs) are being developed - Nyquist sampling and oversampling converters. Complete systems with digital sampling at rates of /spl sim/20 GHz and above have been demonstrated using low-temperature superconductor device technology. Some ADC components have also been implemented using high-temperature superconductors. Superconductor ADCs have unique applications in true digital-RF communications, broadband instrumentation, and digital sensor readout. Their designs, test results, and future development trends are reviewed.     

A 4 Gbps current-mode transmitter for 12-bit 250 MSPS ADC

A 4 Gbps transmitter for a 12-bit 250 MSPS pipelined ADCs is presented. A low power current mode (CM) output driver with reverse scaling technique is proposed. A high speed, low power combined serializer is implemented to convert 12 bit parallel data into a seria1 data stream. The whole transmitter is used in a 12-bit 250 MSPS pipelined ADC for the digital output buffer and fabricated in 180 nm 1. 8 V 1P5M CMOS technology. Test results show that the transmitter provides an eye height greater than 800 mV for data rates of both 2 Gbps and 4 Gbps, the 12-bit 250 MSPS ADC achieves the SNR of 69.92 dBFS and SFDR of 81.17 dB with 20.1 MHz input at full sampling speed. The ADC with the 4 Gbps transmitter consumes the power consumption of 395 mW, where the power consumption of transmitter is 75 mW. The ADC occupies an area of 2.5×3.2 mm², where the active area of the transmitter block is 0.5×1.2 mm².     

A/D and D/A conversion for telecommunication

Emerging telecom systems such as ADSL and VDSL demand state-of-the-art high speed and high resolution analog-to-digital converters (ADCs) and digital-to-analog converters (DBCs). Moreover, cost and power consumption issues require the use of specific A/D and D/A architectures to achieve the wanted resolution at the required speed at minimum power. In the first part of this article we present an overview of the various ADC and DAC architectures used in Alcatel Telecom systems over the past 15 years, with an emphasis placed on the evolution of ADCs and DACs for today's asymmetrical-digital-subscriber-loop (ADSL) applications. We then discuss design considerations for high-speed and high resolution ADCs for future very-high-data-rate digital subscriber-line (VDSL) technology     

High-resolution background calibrated ADCs for software-defined radios

Next-generation transceivers operating with different standards require the existence of a wide bandwidth and highly linear analog-to-digital converters (ADCs) to enable software-defined radios (SDR). Several methods dealing with the design and implementation of high-resolution and high-speed ADCs to provide the stringent requirements of the wide-bandwidth transceivers are presented. A special focus is made on pipelined ADC for its superior performance in terms of speed and resolution. A digital background calibration technique to compensate for the capacitors mismatch, and the finite opamps gain is presented. Low overhead digitally oriented technique to increase the speed of the ADC beyond the technological limits by overcoming the problems of the conventional time-interleaving is also presented. Simulation results prove the effectiveness of these techniques.