低照度CMOS图像传感器设计与实现

设计了一种基于电容反馈跨阻放大器型（Capacitive Trans-impedance Amplifier,CTIA）像元电路与双采样（Delta Double Sampling,DDS）的低照度CMOS图像传感器系统。采用CTIA像元电路提供稳定的光电二极管偏置电压以及高注入效率,完成在低照度情况下对微弱信号的读取;同时采用数字DDS结构,通过在片外实现像元积分信号与复位信号的量化结果在数字域的减法,达到抑制CMOS图像传感器中固定图案噪声的目的,进一步提高低照度CIS的成像质量。基于0.35 m标准CMOS工艺对此基于CTIA像元电路的CMOS图像传感器芯片进行流片,像元阵列为256256,像元尺寸为16 m16 m。测试结果表明该低照度CMOS图像传感器系统可探测到0.05 lx光照条件下的信号。     

Analysis of temporal noise in CMOS photodiode active pixel sensor

Temporal noise sets the fundamental limit on image sensor performance, especially under low illumination and in video applications. In a CCD image sensor, temporal noise is primarily due to the photodetector shot noise and the output amplifier thermal and 1/f noise. CMOS image sensors suffer from higher noise than CCDs due to the additional pixel and column amplifier transistor thermal and 1/f noise. Noise analysis is further complicated by the time-varying circuit models, the fact that the reset transistor operates in subthreshold during reset, and the nonlinearity of the charge to voltage conversion, which is becoming more pronounced as CMOS technology scales. The paper presents a detailed and rigorous analysis of temporal noise due to thermal and shot noise sources in CMOS active pixel sensor (APS) that takes into consideration these complicating factors. Performing time-domain analysis, instead of the more traditional frequency-domain analysis, we find that the reset noise power due to thermal noise is at most half of its commonly quoted kT/C value. This result is corroborated by several published experimental data including data presented in this paper. The lower reset noise, however, comes at the expense of image lag. We find that alternative reset methods such as overdriving the reset transistor gate or using a pMOS transistor can alleviate lag, but at the expense of doubling the reset noise power. We propose a new reset method that alleviates lag without increasing reset noise     

A High-Speed Low-Noise CMOS Image Sensor With 13-b Column-Parallel Single-Ended Cyclic ADCs

A high-performance CMOS image sensor (CIS) with 13-b column-parallel single-ended cyclic ADCs is presented. The simplified single-ended circuits for the cyclic ADC are squeezed into a 5.6-mum-pitch single-side column. The proposed internal reference generation and return-to-zero digital signal feedback techniques enhance the ADC to have low read noise, a high resolution of 13 b, and a resulting dynamic range of 71 dB. An ultralow vertical fixed pattern noise of 0.1 e_rms ^- is attained by a digital CDS technique, which performs A/D conversion twice in a horizontal scan period (6 mus). The implemented CIS with 0.18-mum technology operates at 390 frames/s and has 7.07-V/lx middots sensitivity, 61- muV/e^- conversion gain, 4.9-e_rms ^- read noise, and less than 0.4 LSB differential nonlinearity.     

用于CMOS图像传感器的12位低功耗单斜坡模数转换器设计

 本文提出了一种应用于CMOS图像传感器中的高精度低功耗单斜坡模数转换器(single slope analog-to-digital converter)设计方案.该ADC方案由可变增益放大器、前置预放大器和动态锁存比较器组成.相比现有的设计方案,本文提出的电路在不牺牲噪声性能的前提下,具有更低的功耗和更小的芯片面积.通过集成列并行的单斜坡模数转换器在最新设计的高精度高速CMOS图像传感器设计中,实验结果证明了设计的有效性.     

包含交流耦合CTIA与数字CDS的CMOS图像传感器设计

设计了一种带隔直电容的交流耦合CTIA像元电路与数字相关双采样（DCDS）结构的CMOS图像传感器系统。在传统的CTIA像元电路中增加隔直电容,通过控制光电二极管的偏压,达到减小光电二极管暗电流的目的;同时采用片外数字CDS结构,通过在片外实现复位信号与像元积分信号的量化结果在数字域的减法,可以减小图像传感器像元的复位噪声和固定图案噪声（FPN）。基于0.35 m标准CMOS工艺对此CMOS图像传感器进行流片,像元阵列为256256,像元尺寸为16 m16 m。测试结果表明交流耦合CTIA像元电路可以将光电二极管的偏压控制在零偏点附近,此时其暗电流最小;采用了数字CDS结构后,图像传感器像元的时域噪声及固定图案噪声均有不同程度降低。     

一种6T像素全局曝光CMOS图像传感器

提出了一种基于6T像素结构的全局曝光CMOS图像传感器。通过采用PPD结构的6T像素、高复位电平和低阈值器件,提高了动态范围,并优化设计了像素单元的版图,使之获得较高的填充系数;模拟读出电路部分,通过采用双采样、增益放大和减小列级固定模式噪声(FPN)处理,以及对列选控制电路进行优化,减小了对全局PGA的运放设计要求。芯片的工作频率为20MHz,动态范围为66dB,实现了全局曝光方式CMOS图像传感器的设计。     

Wide dynamic range CMOS image sensor with in-pixel double-exposure and synthesis

A wide-dynamic-range CMOS image sensor (CIS) based on synthesis of a long-time and a short-time exposure signal in the floating diffusion (FD) of a five-transistor active pixel is proposed.With optimized pixel operation,the response curve is compressed and a wide dynamic range image is obtained.A prototype wide-dynamic-range CMOS image sensor was developed with a 0.18 μm CIS process.With the double exposure time 2.4 ms and 70 ns,the dynamic range of the proposed sensor is 80 dB with 30 frames per second (fps).The proposed CMOS image sensor meets the demands of applications in security surveillance systems.     

A low-noise low-offset capacitive sensing amplifier for a 50-/spl mu/g//spl radic/Hz monolithic CMOS MEMS accelerometer

This paper describes a CMOS capacitive sensing amplifier for a monolithic MEMS accelerometer fabricated by post-CMOS surface micromachining. This chopper stabilized amplifier employs capacitance matching with optimal transistor sizing to minimize sensor noise floor. Offsets due to sensor and circuit are reduced by ac offset calibration and dc offset cancellation based on a differential difference amplifier (DDA). Low-duty-cycle periodic reset is used to establish robust dc bias at the sensing electrodes with low noise. This work shows that continuous-time voltage sensing can achieve lower noise than switched-capacitor charge integration for sensing ultra-small capacitance changes. A prototype accelerometer integrated with this circuit achieves 50-/spl mu/g//spl radic/Hz acceleration noise floor and 0.02-aF//spl radic/Hz capacitance noise floor while chopped at 1 MHz.     

A Packaged and ESD-Protected Inductorless 0.1–8 GHz Wideband CMOS LNA

In this letter, an inductorless 0.1-8 GHz wideband CMOS differential low noise amplifier (LNA) based on a modified resistive feedback topology is proposed. Without using any passive inductors, the modified resistive feedback technique implemented with a parallel R-C feedback, an active inductor load, and neutralization capacitors achieves high gain, low noise, and good return loss over a wide bandwidth. To ensure the robustness in the system integration, electro-static discharge diodes are added to the radio frequency pads. The LNA was fabricated using a digital 90 nm CMOS technology. It achieves a 3 dB bandwidth of 8 GHz with a 16 dB voltage gain, noise figures from 3.4 dB to 5.8 dB across the whole band, and an input third-order intermodulation product (IIP3) of -9 dBm. The active area of the chip is 0.034 mm². The chip was packaged and tested on an FR4 PCB using the chip-on-board approach.     

一种应用于CMOS图像传感器数字双采样ADC的PGA电路

提出了一种应用于CMOS图像传感器数字双采样模数转换器(ADC)的可编程增益放大器(PGA)电路。通过增加失调采样电容,采集PGA运放和电容失配引入的失调电压,在PGA复位阶段和放大阶段进行相关双采样和放大处理,通过数字双采样ADC将两个阶段存储电压量化,并在数字域做差,降低了PGA电路引入的固定模式噪声。采用0.18μm CMOS图像传感器专用工艺进行仿真,结果表明:在输入失调电压-30~30mV变化区间,提出的PGA的输出失调电压可以降低到1mV以下,相比传统PGA输出失调电压随输入失调电压单倍线性关系而言大大降低了列固定模式噪声。     

A 3–8 GHz Low-Noise CMOS Amplifier

A wideband CMOS low-noise amplifier (LNA) is proposed by using the concept of mutual coupling technique implemented through a symmetric center-tap inductor. A frequency widening network is designed with a center-tap inductor at the input and the output of an LNA to achieve bandwidth extension with a single stage amplifier. The proposed wideband low noise amplifier is implemented in the 0.18 mum CMOS technology. This design obtains a bandwidth of 3-8 GHz with a power consumption of 3.77 mW from a 1.8 V supply.     

Ultra-wideband CMOS low noise amplifier

A two-stage ultra-wideband CMOS low noise amplifier (LNA) is proposed. The first stage is optimised for wideband input matching and low noise figure, while the second stage is optimised to extend the -3 dB bandwidth of the overall amplifier. The combination of stages can provide lower noise figure and wider bandwidth simultaneously over that of previously reported feedback-based CMOS amplifiers. The implemented LNA shows a peak gain of 13.5 dB, more than 8.5 dB of input return loss, and a noise figure of 2.5-7.4 dB over a -3 dB bandwidth from 2 to 9 GHz with DC power consumption of 25.2 mW.     

Design of a low-power 3.5-GHz broad-band CMOS transimpedance amplifier for optical transceivers

This paper describes a novel low-power low-noise CMOS voltage-current feedback transimpedance amplifier design using a low-cost Agilent 0.5-/spl mu/m 3M1P CMOS process technology. Theoretical foundations for this transimpedance amplifier by way of gain, bandwidth and noise analysis are developed. The bandwidth of the amplifier was extended using the inductive peaking technique, and, simulation results indicated a -3-dB bandwidth of 3.5 GHz with a transimpedance gain of /spl ap/60 dBohms. The dynamic range of the amplifier was wide enough to enable an output peak-to-peak voltage swing of around 400 mV for a test input current swing of 100 /spl mu/A. The output noise voltage spectral density was 12 nV//spl radic/Hz (with a peak of /spl ap/25 nV//spl radic/Hz), while the input-referred noise current spectral density was below 20 pA//spl radic/Hz within the amplifier frequency band. The amplifier consumes only around 5 mA from a 3.3-V power supply. A test chip implementing the transimpedance amplifier was also fabricated using the low-cost CMOS process.     

A low supply voltage SiGe LNA for ultra-wideband frontends

A low-power low-noise amplifier (LNA) for ultra-wideband (UWB) radio systems is presented. The microwave monolithic integrated circuit (MMIC) has been fabricated using a commercial 0.25-/spl mu/m silicon-germanium (SiGe) bipolar CMOS (BiCMOS) technology. The amplifier uses peaking and feedback techniques to optimize its gain, bandwidth and impedance matching. It operates from 3.4 to 6.9GHz, which corresponds with the low end of the available UWB radio spectrum. The LNA has a peak gain of 10dB and a noise figure less than 5dB over the entire bandwidth. The circuit consumes only 3.5mW using a 1-V supply voltage. A figure of merit (FoM) for LNAs considering bandwidth, gain, noise, power consumption, and technology is proposed. The realized LNA circuit is compared with other recently published low-power LNA designs and shows the highest reported FoM.     

一种基于0.18μm CMOS工艺的上电复位电路

介绍了一种采用0.18μm CMOS工艺制作的上电复位电路。为了满足低电源电压的设计要求,采用低阈值电压(约0V)NMOS管和设计的电路结构,获得了合适的复位电压点;利用反馈结构加速充电,提高了复位信号的陡峭度;利用施密特触发器,增加了电路的迟滞效果。电路全部采用MOS管设计,大大缩小了版图面积。该上电复位电路用于一种数模混合信号芯片,采用0.18μm CMOS工艺进行流片。芯片样品电路测试表明,该上电复位电路工作状态正常。     

A low-noise CMOS instrumentation amplifier for thermoelectricinfrared detectors

A low-noise CMOS instrumentation amplifier for low-frequency thermoelectric infrared sensor applications is described which uses a chopper technique to reduce low-frequency noise and offset. The offset reduction efficiency of the band-pass filter, implemented to reduce residual offset due to clock feedthrough, has been analyzed and experimentally verified. The circuit has been integrated in a transistor-only 1-μm single-poly n-well CMOS process. It features a gain of 52 dB with a 500 Hz bandwidth and a common-mode rejection ratio (CMRR) of more than 70 dB. The equivalent input low frequency noise is 15 nV/√Hz. The typical residual input offset is 1.5 μV. The amplifier power consumption is 1.3 mW     

一种提高阻变存储器擦除可靠性的写电路设计

针对现有阻变存储器中严重影响擦除操作可靠性的"写回"现象,结合测试数据、材料特性及电路原理分析了引起这种现象的主要原因,给出了一种加入"擦除反馈"功能的写电路设计方案。该方案能够对擦除操作进行监控,一旦发现操作完成,立即使用反馈电路关闭写驱动的输出以停止擦除操作,防止"写回"现象。优化后的写电路方案在0.13μm标准CMOS工艺下进行了流片验证。通过测试数据的分析对比,可以看到相比传统的写电路方案,采用文中的电路设计能明显降低"写回失效"的可能,大幅度提高擦除操作的可靠性。     

具有30dB增益和1-16GHz带宽的CMOS低噪声中频放大器

This paper presents a high-gain wideband low-noise IF amplifier aimed for the ALMA front end system using 90-nm LP CMOS technology.A topology of three optimized cascading stages is proposed to achieve a flat and wideband gain.Incorporating an input inductor and a gate-inductive gain-peaking inductor,the active shunt feedback technique is employed to extend the matching bandwidth and optimize the noise figure.The circuit achieves a flat gain of 30.5 dB with 3 dB bandwidth of 1-16 GHz and a minimum noise figure of 3.76 dB.Under 1.2 V supply voltage,the proposed IF amplifier consumes 42 mW DC power.The chip die including pads takes up 0.53 mm~2,while the active area is only 0.022 mm~2.     

A 0.8-3 GHz RF-VGA with 35 dB dynamic range in 0.13μm CMOS

正A wideband variable gain amplifier(VGA) implemented in 0.13μm CMOS technology is presented. To optimize noise performance,an active feedback amplifier with 15 dB fixed gain is put in the front,followed by modified Cherry-Hooper amplifiers in cascade providing variable gain,which adopt dual loop feedback for bandwidth extension.Negative capacitive neutralization and capacitive source degeneration are employed for Miller effect compensation and DC offset cancellation,respectively.Measurement results show that the proposed VGA achieves a 35 dB gain tuning range with an upper 3-dB bandwidth larger than 3 GHz and the input 1 dB compression point of-29 dBm at the lowest gain state,while the minimum noise figure is 9 dB at the highest gain state. The core VGA(without test buffer) consumes 32 mW from 1.2 V power supply and occupies 0.48 mm2 area.     

A 0.1–20 GHz Low-Power Self-Biased Resistive-Feedback LNA in 90 nm Digital CMOS

In this letter, a 0.1–20 GHz low-power low noise amplifier (LNA) is presented. A novel self-biased resistive- feedback topology is proposed. Two inductors inside the feedback loop and a shunt-peaking inductor are exploited to extend the bandwidth. A PMOSFET with inductive degeneration is chosen as the load to boost the gain while maintaining low noise figure (NF) at high frequencies. A source-degeneration inductor is also introduced at the input transistor to ensure good input matching and stability over the entire bandwidth. All inductors are small due to the presence of feedback. The LNA was fabricated using a digital 90 nm CMOS process with 12.7 dB peak power gain, 3.3 dB minimum NF, and ${- 1}~{rm dBm}$ peak input-referred third-order intercept point (IIP3). With 12.6 mW power consumption and 0.12 ${rm mm}^{2}$ active area, this wideband LNA may replace distributed amplifiers (DAs) in many applications.