Description : What are the two most common semiconductor materials used in electronic and electro-optic devices?
Last Answer : Silicon and gallium arsenide.
Description : Explain the silicon semiconductor fabrication process.
Last Answer : Silicon wafer Preparation (2) Epitaxial Growth (2) Oxidation (2) Photolithography (2) Diffusion(2) Ion Implantation (2) Isolation technique (2) Metallization (1) Assembly processing & Packaging (1)
Description : State any four materials used in fabrication of semiconductor device and describe its need.
Last Answer : For fabrication of semiconductor devices like transistors diode, solar cell etc. we have to make use of following types of materials 1. Substrate: o It is used for deposition of thin ... . o Metal cans and sealed glass containers satisfy the extreme requirements of space and military users.
Description : How can loss be reduced during construction (or fabrication) of optical fibers?
Last Answer : By removing the impurities from optical fiber.
Description : Ceramic materials fabrication cannot be done by (A) Welding (B) Slip casting (C) Extrusion (D) Plastic pressing
Last Answer : (A) Welding
Description : Which one of the following is the major disadvantage of stone dies used for crown fabrication, A. They lack accurate reproduction of surface details B. Their overall dimensions are slightly smaller than ... of the stone D. The hazard of aspiration of toxic materials during trimming of the dies.
Last Answer : A. They lack accurate reproduction of surface details
Description : To what circuit arrangement is a common-base detector equivalent?
Last Answer : A diode detector followed by a stage of audio amplification.
Description : Which junction acts as the detector in a common-base detector?
Last Answer : Emitter-base junction.
Description : How is the output signal developed in the common-emitter detector?
Last Answer : By the collector current flow through R4.
Description : Which junction of the transistor in the common-emitter detector detects the modulation envelope?
Last Answer : Emitter-base junction
Description : Sound waves transmitted from a source are sometimes weak when they reach the detector. What instrument is needed to boost the weak signal?
Last Answer : An amplifier.
Description : In the output of an ac error detector, what indicates the (a) direction and (b) amount of control necessary for correspondence?
Last Answer : (a) Phase. (b) Amplitude.
Description : An error signal is the difference between what two quantities fed to the CT (error detector)?
Last Answer : Input signal and feedback.
Description : Why is detector saturation not generally a problem in fiber optic communications systems?
Last Answer : Because fiber optic communications systems operate at low optical power levels.
Description : For efficient operation, should a detector have a high or low responsivity at the operating wavelength?
Last Answer : High.
Description : Describe the operation of an optical detector
Last Answer : It is a transducer that converts an optical signal into an electrical signal. It does this by generating an electrical current proportional to the intensity of incident optical radiation.
Description : What is the function of the detector?
Last Answer : To extract the modulating audio signal.
Description : How can a peak detector for pam be modified to detect pdm?
Last Answer : By making the time constant for charging the capacitor at least 10 times the maximum received pulse width.
Description : What is the time constant of the resistor and capacitor in a peak detector for pam?
Last Answer : At least 10 times the interpulse period.
Description : What characteristic of a pulse does a peak detector sample?
Last Answer : Pulse amplitude or pulse duration
Description : In its simplest form, what functions must a radar detector be capable of performing?
Last Answer : Detecting the presence of rf energy.
Description : How is a quadrature detector changed when used for phase demodulation?
Last Answer : The quadrature grid signal is excited by a reference from the transmitter.
Description : Name two advantages of the gated-beam detector.
Last Answer : Extreme simplicity, few components, and ease of adjustment.
Description : What condition must exist on both the limiter and quadrature grids for current to flow in a gated-beam detector?
Last Answer : Both grids must be positively biased
Description : What circuit functions does the tube in a gated-beam detector serve?
Last Answer : Limits, detects, and amplifies.
Description : What is the primary advantage of a ratio detector?
Last Answer : Suppresses amplitude noise without limiter stages.
Description : What is the function of an fm detector?
Last Answer : Converting frequency variations of received fm signals to amplitude variations
Description : What is the simplest form of fm detector?
Last Answer : Slope detector.
Description : which components act as the filter network in the diode detector?
Last Answer : C1 and R1.
Description : Under what circuit conditions would the shunt detector be used?
Last Answer : When the input voltage variations are too small to give a usable output from a series detector.
Description : How does the current-diode detector differ from the voltage-diode detector?
Last Answer : The current-diode detector is in parallel with the input and load.
Description : What is the function of the diode in a series-diode detector?
Last Answer : Rectifies the rf pulses in the received signal.
Description : What does the simplest diode detector use to reproduce the modulating frequency?
Last Answer : The modulation envelope.
Description : What three functions does the transistor in a regenerative detector serve?
Last Answer : Oscillator, mixer, and detector.
Description : What simple, one-transistor detector circuit uses the heterodyne principle?
Last Answer : Regenerative detector.
Description : To measure incident power, you must rotate the coupler detector of the wattmeter so that the arrow indicating power flow points toward which end of the transmission line?
Last Answer : Load.
Description : What is the name given to the semiconductor device that has three or more elements?
Last Answer : Transistor
Description : What semiconductor device produces electrical energy when exposed to light?
Last Answer : Photovoltaic cell.
Description : What does the letter "N" indicate in the semiconductor identification system?
Last Answer : A semiconductor.
Description : What type of rectifier is constructed by sandwiching a section of semiconductor material between two metal plates?
Last Answer : Metallic rectifier.
Description : Conduction in which type of semiconductor material is similar to conduction in a copper wire?
Last Answer : N-type material.
Description : What are the majority carriers in a P-type semiconductor?
Last Answer : Holes.
Description : What type of PN diode is formed by using a fine metal wire and a section of N-type semiconductor material?
Last Answer : Point-contact.
Description : What are the majority carriers in an N-type semiconductor?
Last Answer : Electrons.
Description : What is the name given to a piece of pure semiconductor material that has an equal number of electrons and holes?
Last Answer : Intrinsic.
Description : Name the two types of current flow in a semiconductor.
Last Answer : Electron flow and hole flow.
Description : State one requirement of an electron tube, which does not exist for semiconductors, that makes the tube less efficient than the semiconductor.
Last Answer : The electron tube requires filament or heater voltage, whereas the semiconductor device does not; consequently, no power input is spent by the semiconductor for conduction.
Description : What is lowest current at which stimulated emission exceeds spontaneous emission in a semiconductor laser called?
Last Answer : Threshold current.
Description : Which semiconductor sources (LD or LED) emit more focused light and are capable of launching sufficient optical power into both single mode and multimode fibers?
Last Answer : LDs.
Description : Semiconductor LEDs emit incoherent light. Define incoherent light
Last Answer : Light waves that lack a fixed-phase relationship