Übungsblatt 4
Bitte laden Sie das aufgefüllte PDF in ILIAS hoch.
Details, Tipps und Tools zum Ausfüllen und Einfügen von Bildern finden Sie unter:
Tools für Lehr/Lern-Veranstaltungen
Name | Vorname | Matrikelnummer |
---|---|---|
$\quad\quad\quad\quad\quad\quad\quad\quad$ | $\quad\quad\quad\quad\quad\quad\quad\quad$ | $\quad\quad\quad\quad\quad\quad\quad\quad$ |
|
Imagine that you work in the company „HHN Mechatronics & Robotics“, which is a cheap mobile EKG – So you want to build a measuring device for the electrocardiogram or the cardiac voltage curve - for athletes and those in need. The measurement signal has only a few millivolts and microamps. In order to protect the signal from electromagnetic radiation on the way from the glued-on electrode to the evaluation electronics, a electromagnetic shielding placed around the line (see Abbildung 1, above). However, since this creates a parasitic capacitor, a colleague suggested active shielding. The shielding is always kept at the measuring voltage that is applied to the line via a voltage follower (see Abbildung 1, under). The parasitic capacitor is never charged due to this structure, since the same voltage prevails on both sides - there is no falsification of the signal. It is important for the application that the voltage follower reacts quickly.
You are supervised with the design of this voltage follower and should use the available operational amplifiers $\rm LM318$, $\rm uA741$, and $\rm uA776$ analyze in the voltage follower circuit.
Write a short report (problem description, circuit in TINA TI, results, discussion) and use TINA TI for the solution.
Analysis
»Transient…
the time course for the specified operational amplifiers. In-depth information (not relevant to the exercise):
1. Derive the voltage gain $A_{\rm V}= {{U_{\rm O}}\over{U_{\rm I}}}$ for the inverting amplifier.
Use the procedure that was used for the non-inverting amplifier.
Take into account that for the differential gain $A_\rm D$ of the ideal OPV applies: $A_\rm D \rightarrow \infty$. And the following also applies: $1/A_\rm D \rightarrow 0$
But the following doesn't always apply: ${{C}\over{U_x \cdot A_\rm D}} \rightarrow 0$, for an unknown constant $C$ and a voltage $U_x$!
2. Which type of amplifier circuit (inverting or non-inverting amplifier) has the lower input resistance? Why?
Below you will find circuits with an ideal operational amplifier, which are similar to the non-inverting amplifier and whose voltage gain $A_V$ must be determined.
Assumptions
Exercises
To approach the problems, you should try to use the knowledge from the inverting amplifier. It can be useful to simulate the circuits via Falstad-Circuit or Tina TI. In the first two circuits, tips can be seen under the illustration as support.
Important: As always in your studies, you should try to generalize the knowledge gained from the task.
Tipps
Abb. 1
Abb. 2
Abb. 3
Abb. 4
Abb. 5
Abb. 6
Abb. 7
Abb. 8
Abb. 9