Experiments #4 Frequency Response Of BJT
Electronics II LabEELE 3120Experiments #4Frequency Response of BJT1) Objectives:To study the frequency response and bandwidth of the common emitter CE-BJT, thecommon collector CC-BJT, and the common base CB-BJT amplifiers.2) Introduction:Most amplifiers have relatively constant gain across a range or band of frequencies, thisband of frequencies is referred to as the bandwidth (BW) of the circuit.Bandwidth means the difference between the upper and lower frequencies of thefrequency response as shown in the figure 4.1Figure 4.1: the frequency response of BJTWhen operated within its bandwidth, the values of π΄π£ & π΄π for an amplifier are calculatedas shown earlier, these values are referred to as mid-band gain values, and aredesignated as π΄π£πππ & π΄ππππ .The frequency response is a graphical representation of the relationship betweenamplifier gain and operating frequency for input signal, as an example sinusoidal signal.Page 1 of 8
Electronics II LabEELE 3120So why we need this type of analysis for an amplifier, because we need to determine the:-To determine the stability region for amplifier systems.To design an amplifier systems that met the required specifications.3) AC & DC Analysis:a) DC Analysis:As we know the frequency in DC is equal zero because there is no oscillation in DCsignal so, the reactance of capacitor is equal infinity that mean the capacitors work asopen circuit.b) AC Analysis:In this analysis we will study the effect of capacitors in different level of frequenciesas: Low frequencyMiddle frequencyHigh frequencyBefore we start our analysis we need first know the names of capacitors and itslocations, there are two type of capacitor: Practical capacitors: Cin, Cout, CE these capacitors are connected as shown infigure 4.1 and itβs effective in low frequency.Virtual capacitors: Cwi, Cwo, CBE, CBC, CCE these capacitors are appears andeffectives on the high frequency because its value in Nano-farad.Page 2 of 8
Electronics II LabEELE 3120Cases of capacitor: At very low frequency the capacitor work as open circuit.At very high frequency the capacitor work as short circuit.At normal frequency the capacitor have a magnitude and effect on thefrequency response.ππ 12πππNow, we will show the relationship between the voltage gain and varying frequencyand defined the regions on this curve as shown in figure 4.2Figure 4.2: The frequency response of BJT amplifierFigure 4.3: The sample circuit diagram of BJT amplifierPage 3 of 8
Electronics II Lab EELE 3120Low frequency response of BJT amplifier: (π ππππ )At this region all capacitors will be open circuit because its reactance will beequal infinity at π 0 and π΄π£ 0.Now, if the frequency increase slightly the voltage gain will be increase also untilthe frequency reach to low cut frequency, after this critical point the capacitorswill be short circuit and voltage gain raise to the maximum value (π΄π£(πππ) ).1- πΆππ ππ‘ πΆππ’π‘ & πΆπΈ short circuit:πππΆππ 12π(π π ππ)πΆππWhere: πππ π 1//π 2//π΅ππ2- πΆππ’π‘ ππ‘ πΆππ & πΆπΈ short circuit:πππΆππ’π‘ 12π(π π π π)πΆππ’π‘3- πΆπΈ ππ‘ πΆππ & πΆππ’π‘ short circuit:πππΆπΈ 1π π π΅ππ2π (π πΈ ) πΆπΈπ΅Where: π π π π //π 1//π 2 High frequency response of BJT amplifier: (πππππ )In this region will be appear the effect of virtual capacitors which called parasiticeffect (πΆπ€π, πΆπ€π, πΆπ΅πΈ, πΆπΆπΈ, πΆπΆπ΅), and its value in Nano-farad.These capacitors at very high frequency will be short circuit and it reactance equalzero, and the voltage gain goes to zero.In this region all practical capacitors are short circuit also.Page 4 of 8
Electronics II LabEELE 31201- At πΆππ, πΆππ’π‘, πΆπΈ are shortcircuit:πΆπ οΏ½οΏ½ πΆπ΅πΈ[1 π΄π£]πΆπ πΆπ€π πΆπ΅πΈ πΆπππΆπ οΏ½οΏ½ πΆπ΅πΆ[1 1]π΄π£πΆπ πΆπ€π πΆπΆπΈ πΆππ2- High frequency law:πβπ 12ππ π‘βπ πΆππβπ 12ππ π‘βπ πΆππ π‘βπ οΏ½ π πΏ//π π//ππPage 5 of 8
Electronics II LabEELE 3120Before we are going to lab work we need to know some important definitionswhich we need them in design.Logarithm:π₯ log π π , π π π₯Why we need log scale? To represent a large scale of frequency start from π»π§ andgoes to ππ»π§.There are two modes of log scale:-Semi Log: that mean the x-axis is logarithm increment and y-axis is linearincrement.Double Log: that mean the x-axis and y-axis are logarithm increment.Decibels: (dB)1 ππ΅ 10 log10π2π11 ππ΅ 20 log10 π΄π£Notes:-To find the Low cut off frequency ππΏ ππ΄π(ππΏπππ , ππΏπππ’π‘ , ππΏππ ).To find the upper cut off frequency ππ» ππΌπ(ππ»π , ππ»π )Page 6 of 8
Electronics II LabEELE 31204) Lab work:Figure 4.4: Common Emitter Amplifier1- Connect the circuit in figure 4.4.2- Adjust the DC power supply at 20Vdc.3- Adjust the function generator to sinusoidal of ππ 1πππ at a frequency 1πΎπ»π§.4- Measure the output voltage Vo RMS value (AC mode in Multi-meter device).5- Calculate π΄π£πππ & 0.707π΄π£πππ which be equal 0.707ππ because the input voltageequal 1πππ.6- Now decrease the frequency of input signal to get π π 0.707ππ on Multi-meterscreen to find ππΏ .7- Then increase the frequency of input signal to get π π 0.707ππ on Multi-meterscreen to find ππ» .8- Now calculate the Bandwidth π΅π ππ» ππΏ .9- Now varying the frequency of function generator according to table 1 shown belowand measure the variable on each level.10- Plot the voltage gain π΄π£ relative to frequency.Page 7 of 8
Electronics II LabEELE 3120Frequency (Hz)Vin (RMS)Vo (RMS)π¨π π½π π½ππ1101001k10k50k100k1M2M5MTable 1: Common Emitter Amplifier result5) Exercise:1- Repeat all steps for common emitter amplifier using Orcad.2- Repeat all steps for emitter follower amplifier which shown below using Orcad.Page 8 of 8
Frequency Response of BJT 1) Objectives: To study the frequency response and bandwidth of the common emitter CE-BJT, the common collector CC-BJT, and the common base CB-BJT amplifiers. 2) Introduction: Most amplifiers have relatively
Thursday, March 24, 2016 - Friday, March 25, 2016 4. The New Frequency Response Obligation 4.1. Frequency Response Standard The new frequency response standard will require each BA to achieve a Frequency Response Measure (FRM) that meets its FRO starting in the 2017 compliance period (i.e. December 2016 through November 2017).
response is easily obtained by means of the inverse Laplace Transform. Frequency-Response Method β Frequency response is the steady-state response of a system to a sinusoidal input. In frequency-response methods, we vary the frequency of the input signal over a certain
the 2012 Frequency Response Initiative Report because the actual frequency nadir was accurately captured. The frequency response analysis tool11 is being used by the NERC Bulk Power System Awareness group for frequency event tracking in supp
High-Frequency Response of CS Amp Take the following circuit and investigate its high-frequency response β First, redraw using a high-frequency small-signal model for the nMOS There are two ways to find the upper 3-dB frequency Ο H β Use open-circuit time constant method
The simulation model in this circuit is designed for frequency response, and the functions not related to frequency response are not implemented. Table 4. BD9E200FP4_AC model pins used for frequency response Pin Name Description VIN Power supply input. EN Enable input. BOOT Pin for bootstrap. SW Switching node. FB Output voltage feedback pin.
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treatment e ects, and propose a novel experimental design in this setting. Our paper adds to both the literature on single-wave and multiple-wave experiments. In the context of single-wave (or two-wave) experiments, existing network experiments include clustered experiments (Eckles et al.,2017;Ugander et al.,2013;Karrer et al.,2021) and satu-
4 Sensor Experiments 4.1 Search & Rescue Experiments Experiments were conducted on February 11, 2005 at the Lakehurst Naval Air Base, NJ as part of the New Jersey Task Force 1 search and rescue train-ing exercise. The purpose of the experiments was to validate the utility of sensor networks for mapping, to characterize the ambient conditions of .
