What is Transfer function: Definition and 362 Discussions

In engineering, a transfer function (also known as system function or network function) of an electronic or control system component is a mathematical function which theoretically models the device's output for each possible input. In its simplest form, this function is a two-dimensional graph of an independent scalar input versus the dependent scalar output, called a transfer curve or characteristic curve. Transfer functions for components are used to design and analyze systems assembled from components, particularly using the block diagram technique, in electronics and control theory.
The dimensions and units of the transfer function model the output response of the device for a range of possible inputs. For example, the transfer function of a two-port electronic circuit like an amplifier might be a two-dimensional graph of the scalar voltage at the output as a function of the scalar voltage applied to the input; the transfer function of an electromechanical actuator might be the mechanical displacement of the movable arm as a function of electrical current applied to the device; the transfer function of a photodetector might be the output voltage as a function of the luminous intensity of incident light of a given wavelength.
The term "transfer function" is also used in the frequency domain analysis of systems using transform methods such as the Laplace transform; here it means the amplitude of the output as a function of the frequency of the input signal. For example, the transfer function of an electronic filter is the voltage amplitude at the output as a function of the frequency of a constant amplitude sine wave applied to the input. For optical imaging devices, the optical transfer function is the Fourier transform of the point spread function (hence a function of spatial frequency).

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  1. Z

    Questions about motion control and the moment of inertia referred to a motor shaft

    hello take a mechanism driven by a DC motor in automation books you find transfer functions such as : G(s) = k1/s(s+k2) normally it s assumed that the moment of inertia referred to motor shaft is a constant the point is that in general it is not a constant take for example a slider - crank...
  2. G

    Process Control (transfer function) problem

    TL;DR Summary: transfer function Hello, I have a doubt on this exercise from my post graduation course: ____________________________________________________________________________________________________ The transfer funtion of a series RL circuit is given by: Determine the answer y(t) for...
  3. W

    Difficult Understanding Magnitude and Phase Shift of Transfer Function

    Hello, My textbook offers the following transfer function as an example. It then goes on to explain that the following equations represent the magnitude and phase shift of the transfer function. However, I am having some difficulty jumping from the first equation to these equations. From...
  4. A

    Oven controller block diagram, transfer function and temperature calcs

    FIGURE 5 shows an electrically heated oven and its associated control circuitry. The current, I, to the oven's heating element is fed from a voltage-controlled power amplifier such that I = EK1. A voltage, VD, derived from a potentiometer, sets the desired oven temperature, TD. The oven...
  5. M

    Engineering How to implement a transfer function in Simulink with variable coefficients?

    The implementations for the two filters in simulink are as follow: For the first filter: For the second one: The obtained results have values of 10^-12, while the expected results should be between 10^-3 - 10. Since it's the first time when I try t implement a tf with variable coefficients I...
  6. Franklie001

    Engineering RLC circuit -- Phasor Transfer Function calculation

    Good morning, I need some help solving those two question. I've attached my attempted solution below. Could i solve the transfer function any further? Thank you for your help
  7. cnh1995

    Engineering What is wrong in this 2nd order transfer function?

    I have attached my attempt at a solution. In the solution image, I have computed 3 things: 1. System transfer function based on my understanding of the problem statement. This is a 2nd order system with steady state dc gain=0.9. So I wrote the transfer function accordingly. However, I strongly...
  8. StoneBored

    How to get the transfer function for force transmissibility of a wall?

    Hi, I am trying to get the transfer function from a wall between rooms. From one side I have the force of a hammer as an input ,and in the other side of the wall (next room) I have an accelerometer. Is it possible to get the TF without know the damping, stiffness and mass of the wall partition...
  9. A

    Engineering Is it possible for a low pass filter to have such a transfer function?

    Hello! Consider this filter,and that I have to find the transfer function U2/U1 with the norm Ω= ωRC (also double fractions are not allowed) Now I can see that that the resistor and capacitor left as well as right are parallel to each other. So simplifying that ## Z_1 = \frac{R}{jωRC +1}...
  10. A

    Engineering How do I draw the Bode diagram of this transfer function?

    Hello! I have this filter here a) Calculate the transfer function T(Ω) = Ua/Ue using voltage dividers.For this, use the normalized angular frequency Ω = ωRC and bring the result into the form ##T(Ω) = \frac{A+jB}{C+jD} ## . The result must not contain any double fractions. I was able to that...
  11. M

    From differential equations to transfer functions

    *** MENTOR NOTE: This thread was moved from another forum to this forum hence no homework template. Summary:: Trying to find transfer functions to design a block diagram on simulink with a PID controller and transfer functions for a water tank system. ----EDIT--- The variables and parameters...
  12. H

    Engineering Decomposition minimal phase & all pass

    Hey everybody! I have put G1 = (1-s)/(2-10s) & G2 = (2-10s)/ (2 +10s) but than I read that all poles and zeroes should be inside the unit circle, and I don't know how to move the Zero S_01 = 1 to the unit circle
  13. A

    Engineering Motion equation and transfer function of mass on a conveyor

    Denote wheel turning angle as theta--> Induced EFM (Em)=Kb*Theta_dot. Voltages on the wheel: R*i= V - Em Moments on engine's axis: Kt*i-C*a + a (m+M)*x_double_dot=0 (As Jm negligible). From here I would find another equation to have x and theta expressing each other, but i think I'm...
  14. MechEEE

    Transfer function with initial conditions (DE)

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  15. AncientOne99

    Engineering Electrical and Control Engineering: Transfer Function Reduction problem

  16. jisbon

    Engineering Magnitude of transfer function

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  17. H

    Engineering Control block diagram's transfer function

    The ac signal is converted to DC signal which is connected to a capacitor to filter the DC signal. The filter DC signal is step down for 12volt to 5 volt using a voltage regulator. The regulated DC signal is connected to a crystal oscillator that converts the DC signal to a square wave signal...
  18. Brian1776

    PID - Root Locus (Sisotool) for Transfer Function with Zeros and Poles

    Hi everyone! I have a 8th order transfer function, you can see it in the first image: % Transfer function num = [2.091,0,203.3,0,-2151,0,-1.072e05]; den = [1,0,-830.4,0,-1.036e05,0,-5.767e05,0,2.412e07]; tf = tf(num, den) I need to use a PID, so I'm trying to use a compensator, adding poles...
  19. wcjy

    Circuits - Transfer function of this LRC circuit

    Got B = 9. My school doesn't provide answers, hence could someone double check if my answers is right? Thanks!
  20. Lord Doppler

    Engineering Transfer function of AC Transformer

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  21. S

    Engineering Finding the natural frequency of transfer function (2s) / (3s^2+5s+2)

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  22. icesalmon

    Engineering Determine the transfer function of the block diagram

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  23. M

    Engineering Converting a series connected transfer function to the state space model

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  24. Will26040

    Engineering Tuning Rules for Lag Dominated FOPDT (first-order plus deadtime) model

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  25. S

    Engineering Write the differential equation that's equivalent to this transfer function

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  26. P

    Engineering 2 j-terms in a transfer function?

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  27. Jason-Li

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  28. jisbon

    Engineering Finding the transfer function for this circuit

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  29. BlueTempus

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  30. S

    Engineering How does feedback affect the transfer function of an integrating block?

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  31. H

    Engineering Finding the argument of a Transfer Function

  32. A

    Engineering Transfer function to block diagram

    I am given the following two equations: and where E_1 is an output with corresponding input e and theta_o is an output with corresponding input E_3. The solutions that I was given are as follows: Unfortunately, I do not understand at all how to work out the block diagrams from the equations...
  33. F

    How to derive a log-antilog opamp square law transfer function?

    Firstly, this is not a homework question. I found a worksheet online with an example of a square law circuit built using log-antilog operational amplifiers. I tried to derive the transfer function but I can't seem to eliminate the reverse saturation current term ##I_S##. I would really...
  34. S

    Steps from state space to transfer function

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  35. S

    Converting linear state space into a transfer function

    My questions are now... Do the steps of converting this space to transfer function include any laplace ? or just we do get [SI-A]-1 and then transfer function is = C* [SI-A]-1 * B As [1 0] * [s-1/det -0.5/det ; 0.5/det s-0.5/det] * [0; 1] = -0.5/s^2+s+0.5 I mean do we need any laplace after that...
  36. R

    Finding the ODE that describes this circuit + find its transfer function

    As you can see, I've tried using KCL at node A to find the 2nd order ODE that describes this circuit in terms of the capacitor voltage. The problem I run into, however, is that I can't find anything to put the node voltage at A in terms of. I've tried (not shown here) doing mesh current as well...
  37. W

    Parameters of a non-standard second-order transfer function

    For a standard second-order system, its transfer function is G(s) = ω2/(s2 + 2ζω + ω2) where ω is the natural frequency and ζ is the damping ratio. But for a non-standard second-order transfer function, G(s) = (2s + 1)/(s2 + 2s + 5), what are its natural frequency and damping ratio? Thank you!
  38. D

    Determine a transfer function in the `s` domain and the response to a ramp input

    1. A process can be represented by the first order equation ##4\frac{dy(t)}{dt}+y(t)=3u(t)## Assume the initial steady state is steady (y=0 at t=-0) (a) Determine the transfer function of this process in the s domain (b) If the input is a ramp change in u(t)=4t, determine the value of...
  39. EastWindBreaks

    Does the transfer function exist for an unforced system?

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  40. Ultisonic

    Transfer Function and Control Systems Question

    ıs there anyone to solve 8th 9th and 10th problems? It is about transfer function and control systems http://avesis.yildiz.edu.tr/DokumanYetki.aspx?SSNO=33&USER=2813Password= 1234
  41. thoraxepi

    I Transfer Function relating momentum and force

    Hey all, I hope this is the correct forum section to post this in. I heard about this problem from a youtube video but I've not been able to simulate it because the video was meant only for an introduction into PID control. Here's the problem: A remote control helicopter is hovering just...
  42. C

    Transfer Function of a FET Differential Amplifier

    Homework Statement [Taken from Razavi's Design of Analog CMOS Integrated Circuits 2nd edition]Homework EquationsThe Attempt at a Solution [/B] I'm not too sure what to do with this question. Here's what I think of the circuit This doesn't look like a differential amplifier to me since...
  43. G

    Factoring Higher Order Polynomials: A Practical Method for Control System Design

    Homework Statement Determine the parameters of the PI controller such that two of the closed-loop poles of the transfer function Gclr(s) correspond to the poles of a second order LTI system with the following specifications: i) overshoot S% = 25%; and ii) settling time ts(5%) = 120 s. Homework...
  44. AndresPB

    Response of a System: Transfer Function

    Some time ago I made a modelling project and obtained a plot. Now, I want to remember what the transfer function was, as I want to try changing the parameters. The graph is the following: How can I obtain the transfer function? Thanks a lot
  45. A

    Calculating Transfer Function of a Curve: A Beginner's Guide

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  46. mjtsquared

    I On the stability of an LTI circuit

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  47. Alex Paul

    Equivalence of torque & angular velocity transfer function

    Hello all, I was doing some behavioural modelling of the torque transfer characteristics of a belt drive system from the driver pulley to the driven pulley. While doing the same, i have tried to see how the angular velocity is getting transferred as well. I would explain my point with the...
  48. C

    Basic Z-Transform Transfer Function

    Homework Statement Hi, I'm asked to find the transfer function for the following digital filter described by a difference equation Homework EquationsThe Attempt at a Solution [/B] Usually if there's no constant term (0.7) here, I can just rearrange in the form of Y(z)/X(z) to give me H(z)...
  49. Y

    Rotational Mast System - Transfer Function, PID Design

    Homework Statement Given the system above, were a motor is rotating a mast that is attached to a second second mast by a spring with a spring constant K and a damping coefficient D. The motor has a current I applied to it with coefficient K Below are the provided values. K_s is the...
  50. P

    Derive analytically the transconductance transfer function

    I am planning to derive analytically the transconductance transfer function (Iout/Vin) of this Gm2.sch circuit block. Is my small-signal model for Gm2.sch correct ?There is one minor mistake (Vgs5 should not be zero). Could anyone spot other mistakes in the small-signal circuit ? I am planning...
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