A New Circuit Topology for the Realization of Very Low-Noise Wide-Bandwidth Transimpedance Amplifier

In this paper, after discussing some important limitations of the most common circuital configuration that is used for the realization of very low-noise transimpedance amplifiers, we propose and analyze a new circuit topology which allows us to obtain significant advantages as far as equivalent input current noise and bandwidth (BW) are concerned. We present a simple circuit implementation of the new transimpedance amplifier, together with the results of its noise characterization. The comparison between these measurements and those obtained on a conventional transimpedance amplifier with the same transimpedance gain has confirmed that the proposed approach allows us to obtain a lower background noise and a larger BW for the same transimpedance gain.     

0.18μm CMOS 2.5Gb/s光接收机跨阻前置放大器的设计

给出了一种利用TSMC 0.18μm CMOS工艺实现的2.5 Gb/s跨阻前置放大器.此跨阻放大器的增益为66.3 dBΩ,3 dB带宽为2.18 GHz,等效输入电流噪声为112.54 nA.在标准的1.8 V电源电压下,功耗为7.74 mW.输入光功率为-10 dBm时,PCML单端输出信号电压摆幅为165 mVp-p.模拟结果表明该电路可以工作在2.5 Gb/s速率上.     

Front-end receiver electronics for high-frequency monolithic CMUT-on-CMOS imaging arrays

This paper describes the design of CMOS receiver electronics for monolithic integration with capacitive micromachined ultrasonic transducer (CMUT) arrays for highfrequency intravascular ultrasound imaging. A custom 8-inch (20-cm) wafer is fabricated in a 0.35-μm two-poly, four-metal CMOS process and then CMUT arrays are built on top of the application specific integrated circuits (ASICs) on the wafer. We discuss advantages of the single-chip CMUT-on-CMOS approach in terms of receive sensitivity and SNR. Low-noise and high-gain design of a transimpedance amplifier (TIA) optimized for a forward-looking volumetric-imaging CMUT array element is discussed as a challenging design example. Amplifier gain, bandwidth, dynamic range, and power consumption trade-offs are discussed in detail. With minimized parasitics provided by the CMUT-on-CMOS approach, the optimized TIA design achieves a 90 fA/√Hz input-referred current noise, which is less than the thermal-mechanical noise of the CMUT element. We show successful system operation with a pulseecho measurement. Transducer-noise-dominated detection in immersion is also demonstrated through output noise spectrum measurement of the integrated system at different CMUT bias voltages. A noise figure of 1.8 dB is obtained in the designed CMUT bandwidth of 10 to 20 MHz.     

Ultralow-noise readout circuit with an avalanche photodiode: toward a photon-number-resolving detector

The charge-integration readout circuit was fabricated to achieve an ultralow-noise preamplifier for photoelectrons generated in an avalanche photodiode with linear mode operation at 77 K. To reduce the various kinds of noise, the capacitive transimpedance amplifier was used and consisted of low-capacitance circuit elements that were cooled with liquid nitrogen. As a result, the readout noise is equal to 3.0 electrons averaged for a period of 40 ms. We discuss the requirements for avalanche photodiodes to achieve photon-number-resolving detectors below this noise level.     

Limiting sensitivity of photodetectors based on A3B5 photodiodes for middle infrared range

The noise of photodetectors based on mid-IR A³B⁵ photodiodes (PhDs) implemented in a transimpedance amplifier scheme is analyzed. Recommendations concerning the choice of amplifier elements depending on the dynamic resistance of PhDs are given. It is shown that, using modern low-noise amplifiers, it is possible to reach a potential limiting threshold sensitivity of photodetectors only using PhDs with dynamic resistances above 50 Ω.     

Electrical Characterization of a Superconducting Hot Spot Microbolometer

We report on fabrication and electrical noise measurements of an antenna coupled hot spot microbolometer operating in vacuum at liquid helium temperature. A noise equivalent power (NEP) of about 40 fW/Hz^1/2 has been measured at the output of a home made transimpedance amplifier operating at room temperature. This result shows the feasibility of microbolometers for a THz-range camera with a simplified electronic readout scheme      

Current Mode Monolithic Active Pixel Sensor With Correlated Double Sampling forCharged Particle Detection

A monolithic active pixel sensor operating in current mode for charged particle detection is described. The sensing element in each pixel is an n-well/p-sub diode with a PMOS transistor integrated in an n-well. The drop of the n-well potential from the collection of charge modulates the transistor channel current. Each pixel features two current mode memory cells. The subtraction of distant-in-time samples frees the signal of fixed pattern noise (FPN) and of the correlated low-frequency temporal noise components, resulting in extraction of the particle footprint. The subtraction circuits are placed at each column end. A transimpedance amplifier, integrating in sequence two current samples and subtracting the results in an arithmetic operation, was adopted. The integrated version of the transimpedance amplifier, designed with a maximized conversion gain, is burdened by a risk of an early saturation, imperiling its operation, if the dispersions of the dc current component are too big. The degree of dispersions could not be estimated during the design. Some number of columns is available as a backup with the direct current readout. An external realization of the subtracting circuit, based on the same principle, is used to process direct output columns. The concept of the data acquisition setup developed, the tested performance of an array of cells, and the processing circuitry are described     

The Design of Extremely Low-Noise Camera-Tube Preamplifiers

The design of current amplifiers suitable for amplifying the signal of camera tubes (or other similar transducers) is presented. Excellent noise performance can be obtained especially at low frequencies. Only one adjustment is required for shaping the frequency response and a very large bandwidth can be obtained. Experimental results are given for an amplifier designed for a camera tube with 15-pF output capacitance. The measured equivalent input noise current of this amplifier is smaller than 1 nA in a 5-MHz frequency band. The bandwidth of the amplifier exceeds 10 MHz.     

Novel transimpedance filter topology for instrumentation

In this paper, a novel transimpedance filter topology is described. It resembles typical Q-Enhancement configurations. Low- and band-pass responses have been fully developed taking into consideration several parameters such as frequency response, input-output impedances and noise. Design conditions are obtained to optimize the performance. Transimpedance filters find direct application with some sensors and D/A converters which provide a current as output signal, avoiding a current to voltage conversion     

Evaluating the bandwidth of an if amplifier in a superheterodyne attenuation meter

Conclusions A superheterodyne attenuation meter, the bandwidth of whose IF amplifier is selected to reduce the random error in measuring a given maximum attenuation, provides smaller random and systematic measurement errors than a meter the bandwidth of whose IF amplifier is selected to provide equal random error components due to frequency instability and thermal noise. Errors in measuring low and medium attenuations will also be smaller with the above method of selecting the IF amplifier's bandwidth, i.e., this bandwidth will be optimum.Translated from Izmeritel'naya Tekhnika, No. 5, pp. 29–31, May, 1967.     

一种降低D类功率放大器开关噪声的设计

传统D类功率放大器因特有的开关噪声对水下电子设备的信号接收、通信控制和信号传输等电信号产生很大的干扰,限制了D类功率放大器在水下电子设备中的广泛应用针对这一现象,首先阐明了Σ-Δ调制的D类功率放大器降低开关噪声的原理,然后对传统调制方式和Σ-Δ调制方式的D类功率放大器进行原理分析,并在Simulink软件中进行仿真对比。仿真结果表明,传统D类功率放大器在开关频率处的开关噪声能量高,Σ-Δ调制的D类功率放大器的开关噪声能量分散在一定的带宽内,并且开关噪声能量峰值低于传统D类功率放大器。     

Very sensitive measurement method of electron devices current noise

The problem of measuring very low levels of current noise in bipoles (linear or not) is dealt with, and a measurement technique is proposed. This technique allows the measurement of noise power spectra 6-10 dB lower than the equivalent input power spectrum of the amplified necessary to perform the measurement. An improvement of 16-20 dB in the sensitivity is obtained with respect to the one of conventional methods, which, for an acceptable accuracy, require the noise of the bipole under test to be 10 dB larger than the equivalent input one of the amplifier. The present method is based on the accurate measurement of the amplifier transimpedance with respect to the input current noise sources and on the precise evaluation and subtraction of the contribution from all the spurious sources to the total noise. The whole procedure is implemented by means of a dual-channel signal analyzer and almost completely automated. The technique has been tested by using it to measure the power spectra of the noise given by known generators, of the Nyquist noise produced by bipoles made up of resistors and capacitors, and of shot noise in p-n junctions. The experimental results agree very well with theoretical predictions     

GaAsHBT直接耦合微波单片集成电路

叙述了基于ＧａＡｓ ＨＢＴ的直接耦合级联形式,设计制造的几种微波单片集成电路,包括２．５Ｇｂ／ｓ跨阻放大器、３ＧＨｚ可级联放大器和１０Ｇｂ／ｓ跨阻放大器的设计、制造和测试结果。     

实用型1.47μmLD泵浦掺Er~3+光纤放大器模块

在国内首次采用国产１．４７μｍ激光二极管和掺Ｅｒ３＋／Ａｌ３＋光纤研制成光电一体化的光纤放大器实用型模块样机。模块净增益２７ｄＢ，饱和输出功率０ｄＢｍ，最大输出功率７ｄＢｍ，光学带宽＞２０ｎｍ，噪声系数＜７ｄＢ，可供光纤通信和光孤子传输实验系统试用。     

Design of high-performance photodiode receivers for optical tomography

The design of instrumentation hardware for tomographic systems must take careful account of measurement noise. This is especially true in near-infrared absorption tomography, where the signal of interest is typically only a few percent of the total signal at the detector, and the available optical power may have to be shared among many measurement channels. In this paper, the monitoring of photodiodes in near-IR absorption tomography is examined in detail, but much of the material is applicable at wavelengths ranging from the UV to beyond 2.5 /spl mu/m. The authors' application involves the frequency region 50 kHz to 2 MHz, which lies above that utilized in the majority of radiometric sensing systems, yet substantially below telecoms bit rates. The problem is further distinguished by the use of phase-sensitive detection schemes, which make local noise density more relevant than wideband noise performance and relax the requirement for dc precision. Alternative transimpedance circuit configurations, including both single-ended and differential topologies, are analyzed with a view to optimization of the signal-to-noise ratio. Typical values of photodiode capacitance and shunt resistance are shown to result in significant noise gain, greatly increasing the importance of amplifier voltage noise relative to other intrinsic noise sources. It is shown that for applications of this type, viable alternatives to the traditionally dominant FET amplifier do exist. The relative susceptibility to coupled interference is also considered. The results of practical tests, involving class-leading operational amplifiers, are presented to support the analyses. These results also underline the need for careful circuit layout and shielding if the capabilities of these devices are to be fully exploited.     

A sensitive magnetoresistive power amplifier

A small, sensitive, low noise, high gain power amplifier, using the anisotropic magnetoresistance effect in thin film permalloy, has been designed and its characteristics calculated. The minimum detectable input current is determined by Johnson noise and hence by input resistance and desired bandwidth. An example of theoretical performance is as follows. For an amplifier unit with approximate dimensions of300 times 300 times 2 mum and with input and load resistances of 50 Ω each the calculated noise at room temperature is equivalent to 10^-8A for a bandwidth (BW) of 1MHz or to 10^-7A for a BW of 100 MHz. At the 10^-8A input current level, the calculated power gain issim 600,000corresponding to a current gain of 775. Power gain decreases with input current asI^{-4/3}, reaching unity atI = 2.1 times 10^{-4}A. Hence, for a BW of 1 MHz, at room temperature, the input current operating range for both amplification and signal-to-noise ratio greater than one is fromI=10^{-8}A to2.1 times 10^{-4}A. To achieve high gain, the amplifier is configured so that the magnetization of the permalloy is biased to lie nominally along the hard axis, the sensing current in the permalloy makes an angle of 45° with the nominal magnetization direction, and the input current produces a magnetic field along the easy axis. This microsize, low noise, silicon compatible power amplifier will be useful in digital and FM applications and possibly as an amplifier for crosstie and bubble memories.     

BiCMOS amplifier–discriminator integrated circuit for gas-filled detector readout

The paper presents a 16-channel amplifier-discriminator designed in BiCMOS technology. It will be used for the binary parallel readout of gas-filled detectors being designed at the European Synchrotron Radiation Facility. The circuit (named AMS211) has been manufactured. The measured transimpedance gain (400 KΩ), bandwidth (25 MHz) and noise (1570 e⁻+95 e⁻/pF ENC) well match the simulated results. The discriminator thresholds are individually controlled by built-in Digital to Analogue Converter. The experience gained with a first prototype of readout electronics indicates that the AMS211 should meet our requirements.     

低噪声电容式MEMS加速度计接口专用集成电路设计

为了提高MEMS电容式加速度计的检测分辨率,降低系统噪声,提出了一种改进的基于开关电容的闭环检测电路.该电路采用新型的电荷积分器实现电容-电压转换,对寄生电容不敏感,具有非常低的噪声,同时,降低了由于运放的有限带宽、有限增益以及失调造成的影响.采用相关双采样（CDS）技术进一步消除了1/f噪声和电路中的失调.同时为了精确模拟传感器的结构部分,对结构的等效电学模型进行了改进,引入两个压控电流源,分别由互为反相的两个时钟信号控制,消除了运放失调、噪声等非理想因素产生的误差.实验制作了ASIC芯片与传感器结构的双片集成微加速度计,芯片采用0.5μmCMOS工艺流片,系统测试结果表明该闭环加速度计的灵敏度为620mV/g,非线性度为0.126%,噪声密度为24μg.Hz-21,整体功耗为30mW.     

5 Gb/s单片集成光接收机前端模拟仿真及研制

基于0．5μm GaAs PHEMT标准工艺研制了850nm单片集成光接收机前端,集成方式为PIN光探测器和跨阻放大器。论文依据已发表的文献数据为基础并借助SILVACO公司的模拟软件建立探测器模型,实验结果表明,模型和实测结果对比有较好的一致性。光接收机最高工作速率5Gb／s,其中,探测器光敏面直径50μm,电容0．51pF,暗电流小于30nA。跨阻放大器-3dB带宽接近10GHz,跨阻增益约43dBΩ,最小等效输入噪声电流密度约为17．6pA／Hz^1/2。