Unit-II BIPOLAR JUNCTION TRANSISTOR INTRODUCTION
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The NTC Thermistors This Is a Negative Temperature Coeffi Cient Resistor Whose Resistance Changes As Ambient Temperature Changes
NTC Thermistors The NTC Thermistors This is a Negative Temperature Coeffi cient Resistor whose resistance changes as ambient temperature changes. Therm- istor comprises 2 or 4 kinds of metal oxides of iron, nickel, cobalt, manganese and copper, being shaped and sintered at high temperature (1200 to 1500 °C) ■ Features ■ Recommended Applications ● Temperature Coeffi cient of Resistance is negative and ● For temperature measurement or temperature detection : extremely large thermometer, temperature controller ● Various kinds of types especially smaller ones are ● For temperature compensation : transistor circuit, available. measuring instruments ● Resistance values are available from 22 Ω to 470 kΩ ■ Physical Characteristics of NTC Thermistors Thermistor is a resistor sensitive to temperature utilizing Fig. 1 the large temperature-coefficient of metal oxide semi- conductor. And its temperature dependency of resistance 1000 value is indicated by the following equation: 1 1 100 R=R0 exp B .................................... (1) ( )[ ( T T 0 )[ ] 10 T0: Standard Temperature 298.15 K(25 °C) 25 0 0 R: Resistance at T K /R 1 T B: Thermistor Constant (K) R B=1000 So called Temperature Coefficient (a) is generally 2000 3000 indicated as follows: 0.1 4000 B 5000 a= .................................................................... (2) T2 0.01 6000 But a is not adequate for use as a constant, because a 0.001 change by temperature is considerably large, so B Value –40 –20 0 20 40 60 80 100 120 140 is used as a coeffi cient of thermistor. T (˚C) ■ Major Characteristics of NTC Thermistors The relation between resistance and temperature of a Fig. 2 thermistor is linear as shown in Fig. -
NTC Thermistors Circuit Protection Components
Product catalog Product NTC thermistors Circuit protection components Cat. No. 129L INDEX 1.Application examples ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 3 2.What are "NTC thermistors"? ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 4 3.Basic specifications ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 4 4.How to choose the right thermistor ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 5 5.How to choose the right power thermistor ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 5 Type desription SEMITEC series name Temperature range ■ Micro thin film thermistor FT thermistor (- 40 ℃ to 250 ℃ ) ‥‥‥‥‥‥‥ 6 - 7 ■ Micro thin film type sensor probe Fµ thermistor (- 10 ℃ to 70 ℃ ) ‥‥‥‥‥‥‥ 8 ■ Thin film thermistor JT thermistor (- 40 ℃ to 100 ℃ ) ‥‥‥‥‥‥‥ 9 ■ Very high accuracy thermistor AP thermistor (- 60 ℃ to 150 ℃ ) ‥‥‥‥‥‥‥ 10 - 11 ■ High accuracy thermistor AT thermistor (- 50 ℃ to 110 ℃ ) ‥‥‥‥‥‥‥ 12 - 13 ■ High sensitivity thermistor ET thermistor (- 50 ℃ to 125 ℃ ) ‥‥‥‥‥‥‥ 14 - 15 ■ SMD type thermistor KT thermistor (- 40 ℃ to 125 ℃ ) ‥‥‥‥‥‥‥ 16 - 17 ■ High temperature thermistor NT thermistor (- 50 ℃ to 300 ℃ ) ‥‥‥‥‥‥‥ 18 CT thermistor (- 50 ℃ to 250 ℃ ) ‥‥‥‥‥‥‥ 19 ■ Non-contact (IR) temperature sensor NC sensor (- 10 ℃ to 150 ℃ ) ‥‥‥‥‥‥‥ 20 Thermopile (- 50 ℃ to 200 ℃ ) ‥‥‥‥‥‥‥ 21 ■ Current regulating diode CRD (- 40 ℃ to 150 ℃ ) ‥‥‥‥‥‥‥ 22 - 23 ■ Voltage regulating diode VRD (- 40 ℃ to 150 ℃ ) ‥‥‥‥‥‥‥ 24 - 25 ■ Inrush current limiter Power thermistor (- 50 ℃ to 200 ℃ ) ‥‥‥‥‥‥‥ 26 - 27 High accuracy Fμ Thermistor AP Thermistor FT Thermistor ET Thermistor JT Thermistor AT Thermistor SMD type KT Thermistor NT Thermistor -
PH-218 Lec-12: Frequency Response of BJT Amplifiers
Analog & Digital Electronics Course No: PH-218 Lec-12: Frequency Response of BJT Amplifiers Course Instructors: Dr. A. P. VAJPEYI Department of Physics, Indian Institute of Technology Guwahati, India 1 High frequency Response of CE Amplifier At high frequencies, internal transistor junction capacitances do come into play, reducing an amplifier's gain and introducing phase shift as the signal frequency increases. In BJT, C be is the B-E junction capacitance, and C bc is the B-C junction capacitance. (output to input capacitance) At lower frequencies, the internal capacitances have a very high reactance because of their low capacitance value (usually only a few pf) and the low frequency value. Therefore, they look like opens and have no effect on the transistor's performance. As the frequency goes up, the internal capacitive reactance's go down, and at some point they begin to have a significant effect on the transistor's gain. High frequency Response of CE Amplifier When the reactance of C be becomes small enough, a significant amount of the signal voltage is lost due to a voltage-divider effect of the source resistance and the reactance of C be . When the reactance of Cbc becomes small enough, a significant amount of output signal voltage is fed back out of phase with the input (negative feedback), thus effectively reducing the voltage gain. 3 Millers Theorem The Miller effect occurs only in inverting amplifiers –it is the inverting gain that magnifies the feedback capacitance. vin − (−Av in ) iin = = vin 1( + A)× 2π × f ×CF X C Here C F represents C bc vin 1 1 Zin = = = iin 1( + A)× 2π × f ×CF 2π × f ×Cin 1( ) Cin = + A ×CF 4 High frequency Response of CE Amp.: Millers Theorem Miller's theorem is used to simplify the analysis of inverting amplifiers at high-frequencies where the internal transistor capacitances are important. -
Thermometrics NTC Diode Thermistors
NTC Diode Thermometrics Thermistors A range of NTC chip thermistors in DO-35 style • Available on axial bandolier to IEC-286-1/ glass package (diode outline) with axial solder- EIA-468A and packet taped to EIA RS-481 for coated copper-clad steel wires. MELF. • Designed for accurate temperature • Also available loose-packed with axial, radial measurement, control and compensation and SMD wire forms • Tight tolerances on resistance and B value • Suitable for automotive, telecom (battery packs), HVAC and white goods applications • Operation up to 482°F (250°C) with excellent stability • Temperature sensing for household appliances such as rice cookers, electronic • Glass body provides hermetic seal and ranges, ovens, etc. voltage insulation and excellent stability • Temperature sensing for industrial products • Designed for cost effective solid state sensor such as pharmaceuticals, chemicals, food, etc.components. • Lead-wires metallurgically bonded to thermistor element for improved reliability (Type GE only) • Resistant to corrosive atmospheres and harsh environments Amphenol Advanced Sensors Type DK 0.08 in (2 mm) 0.02 in (0.5 mm) Specifications DK-N maximum nominal Chip thermistor in DO-35 glass package 1.06 in (27 mm) 0.2 in (4.2 mm) minimum maximum Options DK-H • Other resistance values within the ranges shown; e.g. code DKA302*2 for 3000 Ω 0.08 in (2 0.16 in (4 mm) mm) maximum 0.1 in (2.8 mm) Inside radius ±2% at 77°F (25°C) nominal Ø 0.02 in (0.5 mm) nominal 0.05 in (1.2 • Reference temperatures in the range 0°F mm) nominal to 302°F -
Application Note
VISHAY BCCOMPONENTS www.vishay.com Resistive Products Application Note NTC Thermistors APPLICATIONS AUTOMOTIVE APPLICATIONS INDUSTRIAL, TELECOMMUNICATIONS, CONSUMER NTC temperature sensors are widely used in motor vehicles. In switching, measuring and detection systems For example: • Process control • Inlet air-temperature control • Heating and ventilation • Transmission oil temperature control • Air conditioning • Engine temperature control • Fire alarms • Airco systems • Temperature protection in battery management / charging • Airbag electronic systems systems • Temperature detection of laser diode in CD players for • LCD contrast control in flat-panel displays, mobile phones cars and camcorders • Frost sensors • Temperature compensation of quartz oscillator frequency •ABS in, for example, mobile phones • BMS / charge plugs protection • Ink-jet printer head temperature detection • Video and audio equipment DOMESTIC APPLIANCES • LED control circuits NTC temperature sensors are in virtually all equipment in the home where temperature plays a role. This includes: • Fridges and freezers • Cookers and deep-fat fryers • Washing machines and dish washers • Central-heating systems • Air conditioning SELECTION CHART TOL. LEAD OPERATING B RESP. MAX. ON R (± %) DOCUMENT PRODUCT RANGE TEMP. RANGE TOL. TIME Ø OR Ø L NUMBER (°C) (± %) (s) (mm) ON T (± °C) (mm) (mm) Accuracy line APPLICATION NOTE NTCLE203E3 -40 to +125 (1 , 2, 3, 5) % 0.5 to 2.5 1.7 3.4 0.4 38 min. 29048 NTCLE100E3 -40 to +125 (2, 3, 5) % 0.5 to 3.0 1.2 3.8 0.6 17 min. 29049 two-point NTCLE101E3...SB0 -40 to +125 0.5 °C 1.2 3.3 0.6 17 min. 29046 sensors two-point NTCLE203E3...SB0 -55 to +150 0.5 °C 1.7 4.2 0.5 41 29118 sensors SMD versions NTCS0603E3 -40 to +150 (1, 2, 3, 5) % 1 - - - - 29056 NTCS0402E3 -40 to +150 (1, 2, 3, 5) % 3 - - - - 29003 NTCS0805E3 -40 to +150 (1, 2, 3, 5) % 1 - - - - 29044 NTCS….E3…SMT -40 to +125 1 % 1 - - - - 29151 Revision: 27-Jan-2021 1 Document Number: 29053 For technical questions, contact: [email protected] THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. -
Cascode Amplifiers by Dennis L. Feucht Two-Transistor Combinations
Cascode Amplifiers by Dennis L. Feucht Two-transistor combinations, such as the Darlington configuration, provide advantages over single-transistor amplifier stages. Another two-transistor combination in the analog designer's circuit library combines a common-emitter (CE) input configuration with a common-base (CB) output. This article presents the design equations for the basic cascode amplifier and then offers other useful variations. (FETs instead of BJTs can also be used to form cascode amplifiers.) Together, the two transistors overcome some of the performance limitations of either the CE or CB configurations. Basic Cascode Stage The basic cascode amplifier consists of an input common-emitter (CE) configuration driving an output common-base (CB), as shown above. The voltage gain is, by the transresistance method, the ratio of the resistance across which the output voltage is developed by the common input-output loop current over the resistance across which the input voltage generates that current, modified by the α current losses in the transistors: v R A = out = −α ⋅α ⋅ L v 1 2 β + + + vin RB /( 1 1) re1 RE where re1 is Q1 dynamic emitter resistance. This gain is identical for a CE amplifier except for the additional α2 loss of Q2. The advantage of the cascode is that when the output resistance, ro, of Q2 is included, the CB incremental output resistance is higher than for the CE. For a bipolar junction transistor (BJT), this may be insignificant at low frequencies. The CB isolates the collector-base capacitance, Cbc (or Cµ of the hybrid-π BJT model), from the input by returning it to a dynamic ground at VB. -
1 Light-Emitting Diode
1 Light-emitting diode parameter n is called the ideality factor and usually 1 < n < 2. The parameter VG0 is called the nominal Light Emitting Diodes (LEDs) are the most efficient bandgap voltage of the semiconductor material. 0 light sources. During recent years, the cheap, powerful The voltage across a physical diode V = V + IdRs and reliable LED light bulbs appeared on the market. has also contribution from a parasitic series resistance This is making a true revolution worldwide, as other Rs which is of the order of 1 Ω. Hint: estimate the electrical lighting tools (e.g. incandescent, halogen and magnitudes in the expression above and simplify your fluorescent) in homes and offices are being replaced with calculations accordingly! LED lighting. In this experiment, we will analyse thermal and elec- 1. Measure and plot the voltage–temperature graph of trical properties of the light emitting diodes. the LED at a constant current (your current should You do not need to estimate any uncertainties, but be small enough so that the voltage drop on Rs can the accuracy of your methods and results is important be neglected). and will be graded. Always draw the measurement setup Find VG0. you use! When appropriate, use graphs for determining required quantities. Find the parameters n and A by making additional measurements and a suitable plot. Equipment: 2 identical circuit boards with a LED, res- istor and a temperature sensor on them; 2 transparent At larger currents, the series resistance Rs becomes bottles, 2 airtight caps, 2 tubes, water, syringe, 3 multi- noticeable. Measure this Rs. -
I. Common Base / Common Gate Amplifiers
I. Common Base / Common Gate Amplifiers - Current Buffer A. Introduction • A current buffer takes the input current which may have a relatively small Norton resistance and replicates it at the output port, which has a high output resistance • Input signal is applied to the emitter, output is taken from the collector • Current gain is about unity • Input resistance is low • Output resistance is high. V+ V+ i SUP ISUP iOUT IOUT RL R is S IBIAS IBIAS V− V− (a) (b) B. Biasing = /α ≈ • IBIAS ISUP ISUP EECS 6.012 Spring 1998 Lecture 19 II. Small Signal Two Port Parameters A. Common Base Current Gain Ai • Small-signal circuit; apply test current and measure the short circuit output current ib iout + = β v r gmv oib r − o ve roc it • Analysis -- see Chapter 8, pp. 507-509. • Result: –β ---------------o ≅ Ai = β – 1 1 + o • Intuition: iout = ic = (- ie- ib ) = -it - ib and ib is small EECS 6.012 Spring 1998 Lecture 19 B. Common Base Input Resistance Ri • Apply test current, with load resistor RL present at the output + v r gmv r − o roc RL + vt i − t • See pages 509-510 and note that the transconductance generator dominates which yields 1 Ri = ------ gm µ • A typical transconductance is around 4 mS, with IC = 100 A • Typical input resistance is 250 Ω -- very small, as desired for a current amplifier • Ri can be designed arbitrarily small, at the price of current (power dissipation) EECS 6.012 Spring 1998 Lecture 19 C. Common-Base Output Resistance Ro • Apply test current with source resistance of input current source in place • Note roc as is in parallel with rest of circuit g v m ro + vt it r − oc − v r RS + • Analysis is on pp. -
Dynamic Microphone Amplifier
Dynamic Microphone Preamp Description: A low noise pre-amplifier suitable for amplifying dynamic microphones with 200 to 600 ohm output impedance. Notes: This is a 3 stage discrete amplifier with gain control. Alternative transistors such as BC109C, BC548, BC549, BC549C may be used with little change in performance. The first stage built around Q1 operates in common base configuration. This is unusuable in audio stages, but in this case, it allows Q1 to operate at low noise levels and improves overall signal to noise ratio. Q2 and Q3 form a direct coupled amplifier, similar to my earlier mic preamp . Input and Output Impedance: As the signal from a dynamic microphone is low typically much less than 10mV, then there is little to be gained by setting the collector voltage voltage of Q1 to half the supply voltage. In power amplifiers, biasing to half the supply voltage allows for maximum voltage swing, and highest overload margin, but where input levels are low, any value in the linear part of the operating characteristics will suffice. Here Q1 operates with a collector voltage of 2.4V and a low collector current of around 200uA. This low collector current ensures low noise performance and also raises the input impedance of the stage to around 400 ohms. This is a good match for any dynamic microphone having an impedances between 200 and 600 ohms. The output impedance at Q3 is low, the graph of input and output impedance versus frequency is shown below: Gain and Frequency Response: The overall gain of this pre-amplifier is around +39dB or about 90 times. -
Lecture23-Amplifier Frequency Response.Pptx
EE105 – Fall 2014 Microelectronic Devices and Circuits Prof. Ming C. Wu [email protected] 511 Sutardja Dai Hall (SDH) Lecture23-Amplifier Frequency Response 1 Common-Emitter Amplifier – ωH Open-Circuit Time Constant (OCTC) Method At high frequencies, impedances of coupling and bypass capacitors are small enough to be considered short circuits. Open-circuit time constants associated with impedances of device capacitances are considered instead. 1 ωH ≅ m ∑RioCi i=1 where Rio is resistance at terminals of ith capacitor C with all other v ! R $ i R = x = r #1+ g R + L & capacitors open-circuited. µ 0 π 0 m L ix " rπ 0 % For a C-E amplifier, assuming C = 0 L 1 1 ωH ≅ = Rπ 0 = rπ 0 Rπ 0Cπ + Rµ 0Cµ rπ 0CT Lecture23-Amplifier Frequency Response 2 1 Common-Emitter Amplifier High Frequency Response - Miller Effect • First, find the simplified small -signal model of the C-E amp. • Replace coupling and bypass capacitors with short circuits • Insert the high frequency small -signal model for the transistor ! # rπ 0 = rπ "rx +(RB RI )$ Lecture23-Amplifier Frequency Response 3 Common-Emitter Amplifier – ωH High Frequency Response - Miller Effect (cont.) v R r Input gain is found as A = b = in ⋅ π i v R R r r i I + in x + π R || R || (r + r ) r = 1 2 x π ⋅ π RI + R1 || R2 || (rx + rπ ) rx + rπ Terminal gain is vc Abc = = −gm (ro || RC || R3 ) ≅ −gm RL vb Using the Miller effect, we find CeqB = Cµ (1− Abc )+Cπ (1− Abe ) the equivalent capacitance at the base as: = Cµ (1−[−gm RL ])+Cπ (1− 0) = Cµ (1+ gm RL )+Cπ Chap 17-4 Lecture23-Amplifier Frequency Response 4 2 Common-Emitter Amplifier – ωH High Frequency Response - Miller Effect (cont.) ! # • The total equivalent resistance ReqB = rπ 0 = rπ "rx +(RB RI )$ at the base is • The total capacitance and CeqC = Cµ +CL resistance at the collector are ReqC = ro RC R3 = RL • Because of interaction through 1 ω = Cµ, the two RC time constants p1 ! # rπ 0 "Cπ +Cµ (1+ gm RL )$+ RL (Cµ +CL ) interact, giving rise to a dominant pole. -
A Thermistor Is a Type of Resistor Used to Measure Temperature Changes
Name of student:…………………………………….. 7 PHYSICAL CHARACTERISTICS OF THERMISTOR Task: Determine physical characteristics of a thermistor (constants A and B) from five temperature and resistance measurement. Calculate the resistance of the termistor and the temperature coefficient % at 0, 25 oC using the Equations [3] and [5] and the obtained values A and B. The word thermistor is a combination of words “thermal” and “resistor”. A thermistor is a temperature-sensing element composed of sintered semiconductor material which exhibits a large change in resistance proportional to a small change in temperature. Thermistors can be classified into two types: If the resistance increases with increasing temperature, the device is called a positive temperature coefficient (PTC) thermistor, posistor. If the resistance decreases with increasing temperature, the device is called a negative temperature coefficient (NTC) thermistor. PTC thermistors can be used as heating elements in small temperature-controlled ovens. NTC thermistors are used as resistance thermometers in low-temperature measurements of the order of 10 K. NTC thermistors can be used also as inrush- current limiting devices in power supply circuits. They present a higher resistance initially which prevents large currents from flowing at turn-on, and then heat up and become much lower resistance to allow higher current flow during normal operation. These thermistors are usually much larger than measuring type thermistors, and are purpose designed for this application. Thermistors are also commonly -
Lecture 19 Common-Gate Stage
4/7/2008 Lecture 19 OUTLINE • Common‐gate stage • Source follower • Reading: Chap. 7.3‐7.4 EE105 Spring 2008 Lecture 19, Slide 1Prof. Wu, UC Berkeley Common‐Gate Stage AvmD= gR • Common‐gate stage is similar to common‐base stage: a rise in input causes a rise in output. So the gain is positive. EE105 Spring 2008 Lecture 19, Slide 2Prof. Wu, UC Berkeley EE105 Fall 2007 1 4/7/2008 Signal Levels in CG Stage • In order to maintain M1 in saturation, the signal swing at Vout cannot fall below Vb‐VTH EE105 Spring 2008 Lecture 19, Slide 3Prof. Wu, UC Berkeley I/O Impedances of CG Stage 1 R = in λ =0 RRout= D gm • The input and output impedances of CG stage are similar to those of CB stage. EE105 Spring 2008 Lecture 19, Slide 4Prof. Wu, UC Berkeley EE105 Fall 2007 2 4/7/2008 CG Stage with Source Resistance 1 g vv= m Xin1 + RS gm 1 vv g AgR==out x m vmD1 vvxin + RS gm R gR ==D mD 1 1+ gRmS + RS gm • When a source resistance is present, the voltage gain is equal to that of a CS stage with degeneration, only positive. EE105 Spring 2008 Lecture 19, Slide 5Prof. Wu, UC Berkeley Generalized CG Behavior Rgout= (1++g mrR O) S r O • When a gate resistance is present it does not affect the gain and I/O impedances since there is no potential drop across it (at low frequencies). • The output impedance of a CG stage with source resistance is identical to that of CS stage with degeneration.