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ECE 340 : Electronic Circuits – I Summer 2014 Homework 1

Due on: Thursday, 17/07/2014, 4:00 pm Total marks : 50

Instructions:  Take a print of this document and solve problems on it  Scan this copy and submit it in single .pdf file  Dropbox to submit will be open till 17/07, 4:00 pm  All the best 

Problem 1 ( 8 marks)

The NMOS transistors shown in circuit below have Vt = 1 V, µnCox = 120 µA/V2 , λ = 0 and L1 = L 2 = L3 = 1 m. Find the required values of gate width for each of Q1, Q2 and Q3 to obtain the voltage and current values indicated.

Answers:

W1 =

W2 =

W3 =

ECE 340 : Electronic Circuits – I Summer 2014 Homework 1

Due on: Thursday, 17/07/2014, 4:00 pm Total marks : 50

Instructions:  Take a print of this document and solve problems on it  Scan this copy and submit it in single .pdf file  Dropbox to submit will be open till 17/07, 4:00 pm  All the best 

Problem 1 ( 8 marks)

The NMOS transistors shown in circuit below have Vt = 1 V, µnCox = 120 µA/V2 , λ = 0 and L1 = L 2 = L3 = 1 m. Find the required values of gate width for each of Q1, Q2 and Q3 to obtain the voltage and current values indicated.

Answers:

W1 =

W2 =

W3 =

ECE 340 : Electronic Circuits – I Summer 2014 Homework 1

Due on: Thursday, 17/07/2014, 4:00 pm Total marks : 50

Instructions:  Take a print of this document and solve problems on it  Scan this copy and submit it in single .pdf file  Dropbox to submit will be open till 17/07, 4:00 pm  All the best 

Problem 1 ( 8 marks)

The NMOS transistors shown in circuit below have Vt = 1 V, µnCox = 120 µA/V2 , λ = 0 and L1 = L 2 = L3 = 1 m. Find the required values of gate width for each of Q1, Q2 and Q3 to obtain the voltage and current values indicated.

Answers:

W1 =

W2 =

W3 =

Problem 2 ( 8 marks)

In the circuit shown below, transistors Q1 and Q2 have Vt = 1 V and the process transconductance parameter kn’ = 100 µA/V2. Find V1, V2, and V3 for : (W/L)1 = (W/L)2 = 20

Answers:

V1 =

V2 =

V3 =

Problem 2 ( 8 marks)

In the circuit shown below, transistors Q1 and Q2 have Vt = 1 V and the process transconductance parameter kn’ = 100 µA/V2. Find V1, V2, and V3 for : (W/L)1 = (W/L)2 = 20

Answers:

V1 =

V2 =

V3 =

Problem 2 ( 8 marks)

In the circuit shown below, transistors Q1 and Q2 have Vt = 1 V and the process transconductance parameter kn’ = 100 µA/V2. Find V1, V2, and V3 for : (W/L)1 = (W/L)2 = 20

Answers:

V1 =

V2 =

V3 =

Problem 3 ( 8 marks)

The transistor in the circuit shown below has a very high β. Find VE and VC for VB equal to:

a) 1.45 V b) 0 V

Hint : BJT can be in cut-off as well for some case

Answers:

a) VE = VC =

b) VE = VC =

Problem 3 ( 8 marks)

The transistor in the circuit shown below has a very high β. Find VE and VC for VB equal to:

a) 1.45 V b) 0 V

Hint : BJT can be in cut-off as well for some case

Answers:

a) VE = VC =

b) VE = VC =

Problem 3 ( 8 marks)

The transistor in the circuit shown below has a very high β. Find VE and VC for VB equal to:

a) 1.45 V b) 0 V

Hint : BJT can be in cut-off as well for some case

Answers:

a) VE = VC =

b) VE = VC =

Problem 4 ( 10 marks) For the emitter follower circuit shown below, the BJT used is specified to have β values in the range of 50 to 200 (a distressing situation for the circuit designer  ) For the two extreme values of β i.e. β = 50 and β = 200, find

a) IE, VE and VB b) Draw small signal model c) The input resistance Rin d) The voltage gain V0 / Vsig

C1 = C2 = ∞

Answers:

IE VE VB Rin V0 / Vsig

Problem 4 ( 10 marks) For the emitter follower circuit shown below, the BJT used is specified to have β values in the range of 50 to 200 (a distressing situation for the circuit designer  ) For the two extreme values of β i.e. β = 50 and β = 200, find

a) IE, VE and VB b) Draw small signal model c) The input resistance Rin d) The voltage gain V0 / Vsig

C1 = C2 = ∞

Answers:

IE VE VB Rin V0 / Vsig

Problem 4 ( 10 marks) For the emitter follower circuit shown below, the BJT used is specified to have β values in the range of 50 to 200 (a distressing situation for the circuit designer  ) For the two extreme values of β i.e. β = 50 and β = 200, find

a) IE, VE and VB b) Draw small signal model c) The input resistance Rin d) The voltage gain V0 / Vsig

C1 = C2 = ∞

Answers:

IE VE VB Rin V0 / Vsig

Problem 5 ( 8 marks) A CS amplifier using an NMOS with gm = 3.8 mA/V is found to have an overall voltage gain of -16 V/V. What value should a resistance RS inserted in the source lead have to reduce the overall voltage gain to -8 V/V ?

Answers:

Rs

Problem 6 ( 8 marks) A CS amplifier modeled with the equivalent circuit shown below is specified to have Cgs = 2 pF, Cgd = 0.1 pF, gm = 5mA/V, CL = 2 pF, and RL’ = 25 kΩ. Find

a) Vo / Vsig b) Corner frequency f3dB

Answers:

Vo / Vsig =

f3dB =