NKT electrical components Germany NKT model NKT price

NKT electrical components include single heterojunction, double heterojunction, and quantum well laser diodes. Quantum well laser diodes have the advantages of low threshold current and high output power, making them mainstream products in market applications. Compared to lasers, laser diodes have the advantages of high efficiency, small size, and long life, but their low output power, poor linearity, and less ideal monochromaticity greatly limit their application in cable TV systems, preventing the transmission of multi-channel, high-performance analog signals. In the return module of bidirectional optical receivers, upstream transmission generally uses quantum well laser diodes as the light source.

NKT electrical component principle

When a high-frequency current flows through a conductor, an electric field and a magnetic field are generated in the surrounding space. According to the distribution characteristics of the electromagnetic field in space, it can be divided into the near zone, intermediate zone, and far zone. Let R be the distance from a point in space to the conductor. The region where R ﹤﹤ λ/2π is called the near zone, where the electromagnetic field is closely related to the current and voltage in the conductor. The region where R﹥﹥λ/2π is called the far zone, where the electromagnetic field can leave the conductor and propagate into space. Its changes lag behind the current and voltage on the conductor by a certain period, meaning the propagated electromagnetic wave is no longer directly linked to the current and voltage on the wire; the electromagnetic field in this region is called the radiation field. It must be pointed out that when the length of the wire L is much smaller than the wavelength λ, the radiation is very weak; when the length of the wire L increases to be comparable to the wavelength, the current on the wire increases significantly, thereby forming stronger radiation. Transmitting antennas utilize this property of the radiation field to allow transmitted signals to radiate fully into space after passing through the transmitting antenna. How can a conductor become an effective radiating system? First, let us analyze the situation on a transmission line. On a parallel two-wire transmission line, to ensure only energy transmission without radiation, the structure of the two wires must be symmetrical, with currents at corresponding points on the lines being equal in magnitude and opposite in direction, and the distance between the two wires<π. To effectively radiate the electromagnetic field, this symmetry of the transmission line must be broken. Methods such as separating the two conductors at a certain angle or removing one side can destroy the conductor symmetry and produce radiation. By separating the open-circuit transmission line or the conductor at a distance of π/4 from the terminal in a straight line, the current on the terminal conductor becomes in-phase rather than anti-phase, causing the radiation fields of this conductor segment at spatial points to superimpose in phase, constituting an effective radiation system. This is the simplest and most basic unit antenna, known as a half-wave dipole antenna, with a characteristic impedance of 80Ω. After electromagnetic waves are radiated from the transmitting antenna, they propagate in all directions. If a symmetric dipole is placed in the direction of electromagnetic wave propagation, an induced electromotive force will be generated on the antenna dipole under the action of the electromagnetic wave. If the antenna is connected to receiving equipment at this time, a high-frequency current will be generated at the input end of the receiving equipment. Thus, the antenna acts as a receiver, converting electromagnetic waves into high-frequency current; in other words, the antenna functions as a receiving antenna. The quality of reception depends not only on the strength of the radio waves but also on the directivity of the antenna and the matching between the half-wave symmetric dipole and the receiving equipment.

NKT electrical component principle

P-type semiconductor is formed by doping a small amount of trivalent element impurities, such as boron, into an intrinsic semiconductor (a completely pure, structurally intact semiconductor crystal). Since a boron atom has only three valence electrons, it forms covalent bonds with surrounding silicon atoms. Due to the lack of one electron, a vacancy is created in the crystal. When electrons on adjacent covalent bonds gain energy, they may fill this vacancy, turning the boron atom into an immobile negative ion, while the original silicon atom's covalent bond forms a hole due to the missing electron. However, the entire semiconductor remains neutral. In this P-type semiconductor, conduction is primarily via holes, which are the majority carriers, while free electrons are the minority carriers. The principle of forming N-type semiconductors is similar to that of P-type. Pentavalent atoms, such as phosphorus, are doped into the intrinsic semiconductor. After doping, they form covalent bonds with silicon atoms, generating free electrons. In N-type semiconductors, electrons are the majority carriers, and holes are the minority carriers. Therefore, by doping trivalent and pentavalent impurity elements into two different regions of an intrinsic semiconductor, P-type and N-type regions are formed. Based on the characteristics of N-type and P-type semiconductors, a concentration difference of electrons and holes appears at their junction. Both electrons and holes diffuse from regions of high concentration to regions of low concentration, disrupting the electrical neutrality at the original junction. PN junction unidirectional conductivity: When a forward voltage V is applied across the PN junction, the equilibrium state of the PN junction is broken under the influence of this external electric field. Holes in the P region and electrons in the N region move toward the PN junction. Holes neutralize the negative ions in the P region of the PN junction, and electrons neutralize the positive ions in the N region of the PN junction, thereby narrowing the PN junction. As the external electric field increases, diffusion motion strengthens further, while drift motion weakens. When the external voltage exceeds the threshold voltage, the PN junction acts as a resistor with very low resistance, meaning the PN junction is conducting.

NKT electrical component applications

The structure and characteristics of Schottky diodes make them suitable for high-frequency rectification in low-voltage, high-current output applications. They are used for detection and mixing at very high frequencies (such as X band, C band, S band, and Ku band) and as clamps in high-speed logic circuits. In addition to the characteristic parameters of ordinary PN junction diodes, the electrical parameters of Schottky diodes used for detection and mixing include intermediate frequency impedance, voltage standing wave ratio, and noise figure. The Schottky barrier diode is a low-power, ultra-high-speed semiconductor device. Its most significant feature is an extremely short reverse recovery time (as low as a few nanoseconds). It is commonly used as a high-frequency, low-voltage, high-current rectifier diode, freewheeling diode, and protection diode. It is also used as a rectifier diode and small-signal detection diode in circuits such as microwave communications. It is relatively common in communication power supplies, variable frequency drives, etc. A typical application is in the switching circuit of a bipolar junction transistor BJT, where a Shockley diode is connected to BJT for clamping. This keeps the transistor close to the cutoff state even when conducting, thereby increasing the switching speed of the transistor. The main feature of Schottky diodes is a relatively small forward voltage drop. At the same current, its forward voltage drop is much smaller. Additionally, it has a short recovery time. It also has some disadvantages: relatively low withstand voltage and slightly higher leakage current. These factors must be comprehensively considered during selection.

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