EKT 204 ANALOG ELECTRONIC CIRCUIT 1 - ASSIGNMENT 3 -

EKT 204 – ANALOG ELECTRONIC CIRCUIT 1 - ASSIGNMENT 3 - -2Question 1 The common-collector NPN amplifier in Figure 1 has the following transistor p...
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EKT 204 – ANALOG ELECTRONIC CIRCUIT 1

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ASSIGNMENT 3 -

-2Question 1

The common-collector NPN amplifier in Figure 1 has the following transistor parameters: β = 150, VBE (ON) = 0.7 V, VA = ∞, VT = 26 mV, R1 = 9 kΩ, R2 = 2 kΩ, RE = 1 kΩ, RL = 3kΩ, CC1 = 47 µF and CC2 = 2.2 µF. Using the figure, answer the following questions. (a)

List TWO (2) differences between common-emitter and common-collector amplifier in term of voltage gain, AV and input resistance, Rin. [Senaraikan DUA (2) perbezaan antara penguat pemancar-sepunya dan pemungut-sepunya dalam terma gandaan voltan, AV and rintangan masukan, Rin.]

(b)

[2 marks/ markah]

VA is an important element of Early Effect. Explain briefly the Early Effect with the aid of an appropriate diagram. [VA ialah elemen penting dalam kesan Early. Terangkan secara ringkas kesan Early dengan bantuan gambarajah yang sesuai.]

(c)

Find the value of Q-point collector current, ICQ. [Cari nilai arus pemungut titik-Q, ICQ.,]

(d)

[2 marks/ markah]

[4 marks/ markah]

Find the value of following small signal parameters: [Cari nilai parameter-parameter isyarat kecil berikut:]

(i) output resistance, ro. [rintangan keluaran, ro..]

[1 mark/ markah]

…3/(ii) base-emitter input resistance, rπ. [rintangan masukan asas-pemancar, rπ..]

[1 mark/ markah]

(iii) transconductance, gm. [kealiranpindah, gm..]

[1 mark/ markah]

-3(e)

With the aid of the hybrid-π model equivalent circuit, find the value of small signal voltage gain, AV. [Dengan bantuan litar setara model hybrid-π, cari nilai gandaan voltan isyarat kecil.]

[4 marks/ markah] (f)

Find the input and output impedance of the circuit. [Cari galangan masukan dan keluaran dalam litar tersebut.]

(g)

[2 marks/ markah]

Determine the value of low frequency response, fL. [Tentukan nilai sambutan frekuensi rendah, fL..]

[3 marks/ markah]

Rout

Rin

Figure 1 [Rajah 1]

-4Question 2 [Soalan 2]

The transistor parameters for the amplifier circuit in Figure 2 are VTN = 2 V, Kn = 0.8 mA/V2, Cgs = 2 pF, Cgd = 0.5 pF and λ = 0.015 V-1. Assume VDD = 10 V, Rsi = 10 kΩ, R1 = 120 kΩ, R2 = 280 kΩ, RS = 3.3 kΩ and RL = 10 kΩ. [Parameter –parameter transistor bagi litar penguat dalam Rajah 2 adalah VTN = 2 V, Kn = 0.8 mA/V2 , Cgs = 2 pF, Cgd = 0.5 pF dan λ = 0.015 V-1. Anggapkan VDD = 10 V, Rsi = 10 kΩ, R1 = 120 kΩ, R2 = 280 kΩ, RS = 3.3 kΩ dan RL = 10 kΩ.]

(a)

Identify the type of amplifier configuration for the circuit in Figure 2. [Kenal pasti jenis konfigurasi penguat bagi litar dalam Rajah 2.]

[1 Mark/ markah] (b)

Given that IDQ = 1.5 mA and VDSQ = 5 V, find the values of: [Diberi IDQ = 1.5 mA dan VDSQ = 5 V, cari nilai-nilai:]

(i) transconductance, gm. [kealiranpindah, gm.]

[2 Marks/ markah] (ii) small signal output resistance, ro. [rintangan keluaran isyarat kecil, ro.]

[1 Mark/ markah]

(c)

Sketch and label the high frequency equivalent circuit for Figure 2. [Lakar dan labelkan litar setara frekuensi tinggi bagi Rajah 2.]

[5 Marks/ markah] (d)

Find the following values: [Cari nilai-nilai berikut:]

(i) midband gain for the circuit. [gandaan voltan jalur tengah bagi litar tersebut.]

[4 Marks/ markah]

…5/-

-5(ii) equivalent Miller capacitance. [2 Marks/ markah]

[kapasitor setara Miller .]

(iii) upper cutoff frequency introduced by input capacitance. [frekuensi potong atas disebabkan oleh kapasitor masukan.]

[3 Marks/ markah] (iv) upper cutoff frequency introduced by output capacitance. [frekuensi potong atas disebabkan oleh kapasitor keluaran.]

[2 Marks/ markah]

VDD

R1 RSi

CC1 CC2

Vsi

R2 RS

Figure 2 [Rajah 2]

RL

Vo

-6Question 3 [Soalan 3]

(a)

Explain TWO (2) advantages of Metal Oxide Semiconductor Field Effect Transistor (FET). [Terangkan DUA (2) kelebihan Transistor Kesan Medan Separuh Pengalir Logam Oksida (MOSFET).]

[2 marks/ markah]

(b)

Sketch and label the drain current, ID versus drain-source voltage, VDS characteristic for N-channel and P-channel of MOSFET. [Lakar dan labelkan arus saliran, ID lawan voltan saliran-punca, VDS bagi saluran-N dan saluran-P bagi transistor MOSFET.]

[2 marks/ markah]

(c)

Explain briefly the region of operation for the N-channel MOSFET circuit in the Figure 3(i) if VTN = 0.7 V. [Terangkan secara ringkas kawasan operasi bagi litar MOSFET saluran-N di dalam Rajah 3(i) jika VTN = 0.7 V.]

[2 marks/ markah]

VDS VGS

Figure 3(i) [Rajah 3(i)]

…7/-

-7(d)

The transistor parameters for the common-source MOSFET amplifier in Figure 3(ii) are (W/L) = 32, µn = 650 cm2/V-s, Cox = 76.7 nF, VTN = 1.5 V and λ = 0. [Parameter-parameter transistor bagi penguat MOSFET punca-sepunya di dalam Rajah 3(ii) adalah W/L) = 32, µn = 650 cm2/V-s, Cox = 76.7 nF, VTN = 1.5 V dan λ = 0.]

Figure 3(ii) [Rajah 3(ii)]

(i) Find the value of drain resistance, RD if given VGSQ = 3 V and VDSQ = 7 V. [Cari nilai perintang saliran, RD jika diberi VGSQ = 3 V dan VDSQ = 7 V.]

[3 marks/ markah] (ii) Sketch and label the small signal equivalent circuit for the common-source MOSFET amplifier. [Lakar dan labelkan litar setara isyarat kecil bagi penguat MOSFET punca-sepunya]

[2 marks/ markah] (iii) Find the value of small signal voltage gain, AV. [Cari nilai voltan gandaan isyarat kecil, AV.]

[6 marks/ markah]

(iv) Explain briefly the purpose of the source resistance, RS and explain the condition of the circuit if RS is bypassed by a capacitor. [Terangkan secara ringkas tujuan perintang punca, RS dan terangkan keadaan litar jika RS dipiraukan oleh satu kapasitor.]

[3 marks/ markah]

-8PART B [BAHAGIAN B]

Question 4 [Soalan 4]

Figure 4 shows a two-stage amplifier circuit where a common emitter PNP amplifier is being driven by a common emitter NPN amplifier. The values for the components are RS = 0.5 kΩ, R1 = 50 kΩ, R2 = 22 kΩ, RC1 = 5 kΩ, RE1 = 4.7 kΩ, RC2 = 10 kΩ, RE2 = 3.5 kΩ, RL = 10 kΩ and VBE1 (on) = VEB2(on) = 0.7 with β = 100 for both transistor. [ Rajah 4 menunjukkan litar penguat dua-peringkat di mana penguat PNP pemancar sepunya dipandu oleh penguat NPN pemancar sepunya. Nilai- nilai komponen adalah RS = 0.5 kΩ, R1 = 50 kΩ, R2 = 22 kΩ, RC1 = 5 kΩ, RE1 = 4.7 kΩ, RC2 = 10 kΩ, RE2 = 3.5 kΩ, RL = 10 kΩ dan VBE1 (on) = VEB2(on) = 0.7 dengan β = 100 bagi kedua-dua transistor.]

(a) Redraw and label the amplifier circuit under DC condition. [Lukiskanr dan labelkan litar penguat tersebut dalam keadaan AT.]

[2 Marks/ markah]

(b) Given V+ = 5 V, V- = -5V, VA1 = VA2 = ∞ and VT = 26 mV. [Diberi V+ = 5 V, V- = -5V, VA1 = VA2 = ∞ and VT = 26 mV.]

(i) Based on circuit in 4(a), find the values of the gm1, gm2, rπ1 and rπ2 using DC analysis. [Berdasarkan litar yang dilukis dalam 4(a), cari nilai – nilai gm1, gm2, rπ1 and rπ2 dengan menggunakan analisis AT.]

[8 Marks/ markah]

(ii) With the transistors replaced by its equivalent hybrid-π model, sketch and label the small signal equivalent circuit of the complete amplifier. [Dengan menggantikan transistor dengan model hybrid- π setara, lakar dan labelkan litar setara isyarat kecil bagi litar yang lengkap]

[4 Marks/ markah]

…9/-

-9(iii)

Prove that the expression for the overall small-signal voltage gain, Av of the circuit as given below. [Buktikan persamaan bagi gandaan keseluruhan isyarat kecil, Av bagi litar tersebut adalah seperti diberi di bawah.]

[5 Marks/ markah]

(iv) Find the value for the overall small-signal voltage gain, Av of the system. [Cari nilai gandaan keseluruhan isyarat kecil, Av bagi sistem tersebut.]

[1 Mark/ markah]

Figure 4 [Rajah 4]

-10Question 5 [Soalan 5]

(a)

Figure 5(i) shows a class-B power amplifier in push-pull configuration with complementary transistor pair, Q1 and Q2. The amplifier receives an input voltage, vi at the input terminal and delivers power to the load resistance, RL. [Rajah 5(i) menunjukkan konfigurasi penguat kuasa kelas-B dengan pasangan transistor, Q1 and Q2. Penguat ini menerima voltan masukan, vi pada terminal masukan dan menghantar kuasa pada rintangan beban, RL]

V+ Q1

vi

vo Q2

RL

VFigure 5(i) [Rajah 5(i)]

(i) With the aid of suitable diagrams, explain the operation of the amplifier if Q1 and Q2 are ideal and matched transistor with sinusoidal input, vi. [Dengan bantuan gambarajah – gambarajah yang sesuai, terangkan operasi penguat ini jika Q1 dan Q2 adalah unggul dan sepadan dengan voltan masukan vi berbentuk sinus.]

[6 Marks/ markah]

(ii) Non-ideal characteristics of the transistor introduce a distortion in the output signal. With the aid of suitable diagram, explain briefly the way to minimize the distortion in Figure 5(i). [Ciri – ciri tidak unggul transistor menghasilkan herotan dalam isyarat keluaran. Dengan bantuan gambarajah yang sesuai, terangkan secara ringkas cara untuk mengurangkan herotan dalam Rajah 5(i).]

[2 Marks/ markah] …11/-

-11(b)

All the transistors in class-AB power amplifier shown in Figure 5(ii) are matched. The parameters of the transistors are: β = 60 and I S = 5 × 10 −13 A . [ Semua transistor dalam penguat kuasa kelas-AB adalah sepadan seperti ditunjukkan dalam Rajah 5(ii). Nilai – nilai transistor adalah β = 60 dan Is = 5x10-13 A.]

(i) Redraw the circuit and label the current flow for each transistor. [Lukis semula litar tersebut dan labelkan arah pergerakan arus untuk setiap transistor.]

[2 Marks/ markah] (ii) Find the quiescent collector currents in the four transistors when v1=v0= 0 V. [Cari arus –arus pemungut bagi keempat-empat transistor apabila v1=v0= 0 V.]

[3 Marks/ markah] (iii) If vo(peak) = 6 V, determine the current gain in the circuit, Ai. [ Sekiranya

, tentukan gandaan arus bagi litar ini, Ai.]

[7 Marks/ markah]

2.5 mA

2.5 mA

Figure 5 (ii) [Rajah 5 (ii)]

-12Question 6 [Soalan 6]

(a)

Explain a difference between thyristor with other switching devices such as FET and BJT. [Terangkan perbezaan di antara thyristor dengan peranti-peranti pensuisan seperti FET dan BJT]

[2 marks/ markah]

(b)

Sketch and label the construction of silicon unilateral switch (SUS). [Lakar dan labelkan pembinaan bagi suis sesisi silikon (SUS)]

(c)

[3 marks/ markah]

Figure 6 shows the amplifier circuit and DC load line for common-emitter NPN amplifier. [Rajah 6 menunjukkan litar penguat dan garis beban AT bagi penguat NPN pemancar-sepunya]

Figure 6 [Rajah 6]

(i) Find the value of base resistor, R2 and collector resistor, RC of the common-emitter amplifier. Given β = 100, VBE (ON) = 0.7 V, VTH = 5 V, VA = ∞, R1 = 50 kΩ, RE = 0.5 kΩ, RL = 10 kΩ, CC1 = CC2 = 2.2 µF. [Cari nilai perintang asas, RB and perintang pemungut, RC bagi penguat pemancar-sepunya. Diberi β = 100, VBE (ON) = 0.7 V, VBB = 5 V, VA = ∞, R1 = 50 kΩ, RE = 0.5 kΩ, RL = 10 kΩ, CC1 = CC2 = 2.2 µF.]

[4 marks/ markah] ...13/-

-13-

(ii) With the suitable diagram, demonstrate that AV = [Dengan menggunakan rajah yang sesuai, demonstrasikan bahawa AV =

. ] [5 marks/ markah]

(d)

Find the value of the upper cutoff frequency, fH. Given β = 100, Cbe = 18 pF, Cbc = 2.6 pF, VA = ∞, rπ = 520 Ω, Ri = 390 Ω, Ro = 1.2 kΩ and AV = -1.7. [Cari nilai bagi frekuensi atas potong, fH. Diberi β = 100, Cbe = 18 pF, Cbc = 2.6 pF, VA = ∞, rπ = 520 Ω, Ri = 390 Ω, Ro = 1.2 kΩ dan AV = -1.7. ]

[6 marks/ markah]