Posts Tagged ‘eletrônica’

Circuitos em Eletronica: Importante Paper Explicativo

sábado, agosto 5th, 2017


ler este paper/e-book elucidativo. Por exemplo, veja texto abaixo:

Chapter 12: Basic Electronics


Voltage is the key to understanding electronics. Without voltage, nothing happens in electronics. What is it? Nobody knows. We know how to generate it. We know what it does. We know how to measure it, but nobody knows what it actually is. It is also called “Electro Motive Force” or “EMF” which is no help whatsoever in knowing what it is. That, is roughly equivalent to saying “the thing that pushes is the thing that pushes” – very true but absolutely no help whatsoever. OK, having admitted that we really don’t know what it is, we can start to say the things we do know about it:

Luz & Fótons: Informação Sobre Tecnologias para Observar Fluxos de Fótons e Ondas de Luz

quinta-feira, janeiro 2nd, 2014

A comprovação de que a fórmula Matrix/DNA seja realmente existente dependeria de se constatar que natural fluxos de fótons tendem a tomarem as mesmas direções e transformações de formas/propriedades do circuito da fórmula. Por isso abro este capitulo, para acompanhar e registrar o avanço de tecnologias que poderiam ser utilizadas com esta meta.

 1) BRUNEL INTERNATIONAL : Patent Application Titled “Method and Device for Adjusting the Bias Voltage of a Spad Photodiode” Published Online (01/02/2014)–Patent-Application-Titled-Method-and-Device-for-Adjusting-the-Bias-Voltage-o-17745065/

Cópia do Artigo para pesquisa pela Matrix/DNA:

By a News Reporter-Staff News Editor at Electronics Newsweekly — According to news reporting originating from Washington, D.C., by VerticalNews journalists, a patent application by the inventors Brunel, John (Grenoble, FR); Tubert, Cedric (Sassenage, FR), filed on May 16, 2013, was made available online on December 26, 2013.

No assignee for this patent application has been made.

Reporters obtained the following quote from the background information supplied by the inventors: “The present disclosure relates to photodetectors, and in particular to single-photon avalanche photodiodes (SPAD).

+ Pesquisa – ( Google search for photodetectors and photodiodes (SPAD): – Photosensors or photodetectors are sensors of light or other electromagnetic energy. There are several varieties… ( continuar a ler)


( Retorno ao texto da Brunel International)

“Photodetectors capable of detecting a single photon are used in many applications such as detecting an object and measuring distances, analyzing DNA or proteins, time-resolved spectroscopy such as fluorescence correlation spectroscopy and fluorescence life-time imaging, as well as inspecting VLSI high-density integrated circuits. Distance measurement can be carried out based on a propagation time of a beam of photons emitted in the form of pulses and reflected on the object.

“One well-known method involves using photodiodes

+ Pesquisa – ( Photodiodes – Google search:

Wikipedia = A photodiode is a type of photodetector capable of converting light into either current or voltage, depending upon the mode of operation.[1] The common, traditional solar cell used to generate electric solar power is a large area photodiode. Photodiodes are similar to regular semiconductor diodes except that they may be either exposed (to detect vacuum UV or X-rays) or packaged with a window or optical fiber connection to allow light to reach the sensitive part of the device. Many diodes designed for use specifically as a photodiode use a PIN junction rather than a p-n junction, to increase the speed of response. A photodiode is designed to operate in reverse bias . Principle of operation = A photodiode is a p-n junction or PIN structure. When a photon of sufficient energy strikes the diode, it creates an electronhole pair. This mechanism is also known as the innerphotoelectric effect. If the absorption occurs in the junction’s depletion region, or one diffusion length away from it, these carriers are swept from the junction by the built-in electric field of the depletion region. Thus holes move toward the anode, and electrons toward the cathode, and a photocurrent is produced. The total current through the photodiode is the sum of the dark current (current that flows with or without light) and the photocurrent, so the dark current must be minimized to maximize the sensitivity of the device. (continuar a ler)

Fig … Symbol for photodiode.

Fig… Three Si and one Ge (bottom) photodiodes


( Retorno ao texto da Brunel International)

 as detection and distance measurement elements, by using an avalanche phenomenon which may occur in the pn junction of photodiodes. An avalanche phenomenon can be triggered in a diode pn junction when the diode is reverse-biased in the vicinity of the breakdown voltage of the junction. This phenomenon can be used in two ways in an avalanche photodiode. If the avalanche photodiode is reverse-biased just below the breakdown voltage, the photodiode then generates an electric current proportional to the intensity of the flow of photons received by the photodiode, with a gain of a few hundred with a semiconductor such as silicon.

“To detect low-intensity flows of photons, one well-known method involves using photodiodes which can be reverse-biased above the breakdown voltage. Such photodiodes are referred to as SPAD photodiodes or Single-Photon Avalanche Diodes or diodes operating in ‘Geiger’ mode. Every time such a photodiode receives a photon, an avalanche phenomenon occurs in the pn junction of the photodiode, thus generating a relatively intense current. To prevent the photodiode from being destroyed by this intense current, the photodiode is connected to a quenching circuit enabling the avalanche process to be stopped a few nanoseconds after it occurred.

“To perform a distance measurement, one well-known method involves lighting a detection zone with a pulsed light source such as a pulsed laser source, and detecting photons reflected by an object present in the detection zone using a detector comprising several SPAD photodiodes, for example disposed according to a matrix configuration. The distance of the object present in the detection zone is assessed on the basis of the propagation time or time of flight (TOF) between the instant a light pulse is emitted and the instant a pulse appears at the terminals of a photodiode, resulting from the avalanche triggering of the photodiode. The measurement accuracy depends particularly on the duration of the light pulses emitted by the source, and the shorter these pulses are, the more accurate the measurement can be.

“In a CMOS-type integrated circuit, powered by a voltage in the order of 3 to 5V, the reverse bias of the SPAD photodiodes at a voltage higher than the breakdown voltage, requires a bias voltage of about 14V. Such a voltage is produced by a high voltage generating circuit, for example using a charge pump enabling the supply voltage to be increased.

“It transpires that the breakdown voltage of a SPAD photodiode can vary greatly from one photodiode to another depending on the manufacturing conditions of the photodiodes. The breakdown voltage may also vary greatly over time particularly depending on the ambient temperature. Now, knowledge of this breakdown voltage is important to determine a minimum bias voltage enabling a SPAD photodiode to be put in condition for detecting a photon. Furthermore, the bias voltage of SPAD photodiodes must not be too high to avoid generating an excessively high so-called ‘dark current’. In addition, the higher this bias voltage is, the more leakage currents there will be in the circuits, and the more difficult the design of these circuits is.

“In certain applications, it can also be desirable to place one or more SPAD photodiodes of a detector in a state in which they will not avalanche trigger under the effect of a photon. Now, cutting off a high voltage such as the bias voltage of SPAD photodiodes requires relatively large transistors that, on the other hand, have a relatively slow switch speed. If the detector comprises a large number of SPAD photodiodes that must be selectively biased, it is hardly conceivable to associate such a transistor with each SPAD photodiode. However, the bias voltage applied to each SPAD photodiode can be lowered below the breakdown voltage using small and fast transistors. However, this solution requires the breakdown voltage of each SPAD photodiode of the detector to be accurately known.

“FIG. 1 represents a characteristic curve of current according to the bias voltage of a SPAD photodiode. The part of this characteristic curve corresponding to a negative bias voltage (reverse bias), comprises two parts C1, C2, respectively before and after the breakdown voltage Vbd of the SPAD photodiode. In the part C1 between 0V and the voltage Vbd, a reverse current substantially constant at a low value passes through the photodiode. In the part C2, beyond the voltage Vbd, the reverse current increases rapidly. FIG. 1 also represents a portion of curve C3 extending from the value of the current at the voltage Vbd to the negative currents and corresponding to the leakage currents in the SPAD photodiode. FIG. 1 also represents the bias voltage Vhv of the SPAD photodiode, the difference between the voltage Vhv and the breakdown voltage Vbd is noted Veb. The difference between the voltage Vhv and a voltage lower than the voltage Vbd, to ensure that the SPAD photodiode cannot avalanche trigger, is noted Vsd. The application of the voltage difference Vsd to the bias voltage Vhv prevents the SPAD photodiode from avalanche triggering.”

In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventors’ summary information for this patent application: “To limit the leakage currents and the dark current, it is desirable for the voltage Vhv to be as low as possible. For a fast switch between active and inactive states of a SPAD photodiode, it is desirable for the voltage difference Vsd to be as low as possible. As a result, it is desirable to monitor with sufficient precision the breakdown voltage Vbd of a SPAD photodiode to adjust the bias voltage Vhv of the photodiode. It is also desirable to be capable of performing such an adjustment sufficiently often to monitor any variations in the voltage Vbd.

“Some embodiments relate to a method for adjusting a bias voltage of a SPAD single-photon avalanche photodiode, comprising successive steps of: applying to a photodiode a first test bias voltage lower than a normal bias voltage applied to the photodiode in a normal operating mode, subjecting the photodiode to photons, reading a first avalanche triggering signal of the photodiode, applying to the photodiode a second test bias voltage, different from the first test bias voltage, subjecting the photodiode to photons, reading a second avalanche triggering signal of the photodiode, increasing the normal bias voltage if the first and second signals indicate that the photodiode did not avalanche trigger, and reducing the normal bias voltage if the first and second signals indicate that the photodiode did avalanche trigger.

“According to one embodiment, several SPAD photodiodes receive the normal bias voltage and the first and second test bias voltages, and supply avalanche triggering signals, the normal bias voltage being increased if the numbers of photodiodes subjected to the first and second bias voltages, that avalanche triggered, are below a threshold value, and reduced if these numbers are higher than or equal to the threshold value.

“According to one embodiment, the threshold value is set to 1.

“According to one embodiment, the method comprises a step of selecting in a set of SPAD photodiodes one or more photodiodes due to receive the first and second test bias voltages.

“According to one embodiment, photodiodes are selected by applying to the selected photodiodes the first and second test bias voltages and to the non-selected photodiodes, the first and second bias voltages reduced by a deactivation voltage.

“According to one embodiment, the first and second test bias voltages are chosen between the normal bias voltage and the normal bias voltage reduced by the deactivation voltage.

“According to one embodiment, the deactivation voltage is set to a value lower than the difference between minimum and maximum breakdown voltages of the photodiodes of the set of photodiodes, such that at the normal bias voltage, the number of inactive photodiodes of the set of photodiodes remains below a threshold value.

“According to one embodiment, the normal bias voltage is adjusted in constant steps.

“According to one embodiment, the normal bias voltage is adjusted periodically or when a temperature difference since a previous adjustment of the normal bias voltage is higher than a temperature threshold value.

“According to one embodiment, the deactivation voltage is set to a minimum value to minimize the size of transistors enabling the deactivation voltage to be generated and applied to the photodiodes to be deactivated.

“Some embodiments also relate to a measuring device comprising a SPAD photodiode and a bias circuit supplying the photodiode with a normal bias voltage in a normal operating mode of the device, the measuring device comprising a calibration circuit configured to implement the method defined above.

“According to one embodiment, the device comprises a set of SPAD photodiodes biased by the bias circuit, and a measuring circuit configured to develop a measurement signal according to avalanche triggering signals coming from the photodiodes of the set of photodiodes.

“According to one embodiment, each photodiode comprises a cathode receiving the normal bias voltage or a test bias voltage and an anode receiving a non-zero deactivation voltage if the photodiode is to be deactivated, and linked to the ground through a resistor.


“Some examples of embodiments of the present disclosure will be described below in relation with, but not limited to, the following figures, in which:

“FIG. 1 described above represents a characteristic curve of a current passing through a SPAD photodiode according to the bias voltage of the photodiode,

“FIG. 2 represents a SPAD photodiode and a bias and control circuit for biasing and controlling the photodiode, according to one embodiment,

“FIG. 3 schematically represents a device for adjusting the bias voltage of SPAD photodiodes, according to one embodiment,

“FIG. 4 represents a sequence of steps of adjusting the bias voltage of a photodiode, according to one embodiment,

“FIG. 5 represents a distribution curve of breakdown voltages of photodiodes coming from a manufacturing line, according to a number of SPAD photodiodes.”


As announced in Nature Photonics, Intel has collaborated with industry, academic, and government partners to develop a silicon-based avalanche photodetector (APD). APDs are light sensors that process optical communications to electrical signals. Intel’s APD has a gain-bandwidth product of 340GHz, the best result ever reported for an APD.

Learn more about Intel’s APD breakthrough by reading the Nature journal article, or view the explanatory animation.

Veja animation here:

Avalanche Photodetector