Op-Amp Biomedical System - Lab Report Example

Name Institution Course Date Abstract This document gives a report on a practical performed in the laboratory on how the operational amplifiers, (Op-Amps) are used in Amplification. It was used for the provision of the procedures to be followed in its practice, the results that were then recorded as conclusions from the results were taken down. The teachings included finding how the Op-Amp could be used as a non-inverting amplifier or as an inverting amplifier. Investigations were done on the operational amplifier on its formation and how it worked. As a way of giving a solution to existing problems, the operating amplifier was made. It was to curb, the usage of germanium transistor which generated power at temperatures of almost 85ͦC that could also be present in aircraft. Table of content INTRODUCTION...........................................................................................................................4 BACKGROUND THEORY............................................................................................................4 THEORETICAL ANALYSIS.........................................................................................................5 PROCEDURE..................................................................................................................................7 DISCUSSION................................................................................................................................13 RESULTS .....................................................................................................................................19 CONCLUSION .............................................................................................................................18 Reference ......................................................................................................................................19 Introduction The Op-Amp was used in instrumentation systems in the biomedical field when signal emanates that are not large from the body required amplification. In many occasions, it’s difficult to distinguish between the small signals and the accompanying noise which is of high level. Therefore, situations like this in the op-amp were found to be usable in further conditional signaling. This was for use in further conditions on signaling as a section in the active removal of noise through filtration. A Proper understanding of the op-amp's operation has mostly become a particular challenge. This is due to the involvement of feedback. The diagram below represents a simple op-amp model. Theoretical analysis Figure 1.1 Operation of an OP-amp circuit In between the two input voltages, is an output voltage that was used to differentiate them. The two input voltages included the Vin- and the Vin+ whereby the –ve is the inverting input, and the +ve is the non-inverting input. The two inputs were multiplied by the gain of the amplifier, denoted as “A.” The ideal amplifier had some properties that made is efficient in the analog circuit practical. The included the zero impedance and the infinite gain. Besides, the infinite input impedance as well as the infinite width of the band facilitated its success in the practical. Due to the high impedance of the contribution, the properties didn't get to be reached in the practical’s first calculation's order. Its high impedance allowed the consideration of the current input as zero practically. Also, the gain loop that was highly open showed that practically Vin- and the Vin+ were the same when the amplifier was operated in a linear area. The gain of the op-amp was then set to a given particular value with the use of the feedback where a portion of the output voltage was taken back to the non-inverting input, and its operations reduced the values of the gain loop that was open into an open circuit that is closed. The presence of the two zero input constraints at the two voltages, Vin- and the Vin+ being equal. Therefore the analysis of nodal was preferably a simpler way of analyzing circuit purposely to achieve the determination of the simple op-amp configuration's range and behavior. Procedure to the practical experiment on non-inverting summing amplifier The machine that was used in the analysis was the OP275 Op-amp. It was manufactured by the Analog Devices Company that processes electronics. The amplifier was packaged with lead Plastic Dual-in-Line Package in the presence of two operating amplifiers. The amplifier had the negative and the positive speakers as well as which were de-coupled by the use of the capacitor for the removal of notice from the power supply rails. Figure Pinout and power connection of the OP275 Operational Amplifier Testing ws done on The schematic of the circuit, and a corresponding diagram that showed a partially complete circuit layout were as shown. Schematic of non-inverting summing op-amp circuit Figure. A wiring diagram of a non-inverting summing op- amp circuit Figure. A partially complete layout diagram of the non-inverting summing circuit of the op-amp Procedure The circuit on wiring was completed. The breadboard designer was opened in the e-lab and the four resistors positioned into the correct position as a way of implementing the wiring diagram. A demonstrator was used to check whether the circuit was complete. For a start, the breadboard was plugged in with three black connectors nearly placed. The OP275 was then connected to the center of the block of the breadboard located at the left-hand, and its notch faced to the left. The positive pin supply was further connected the breadboard’s topmost track with the red wire as the negative supply pin was attached to the lowest path with blue wires. Concerning the wiring diagram, the resistor was inserted and de-coupled capacitor as shown in the diagram. Use of short length of the insulated wires was needed. Therefore the long track adjacent to the negative supply was designated to zero volts, (0V).the breadboard was connected to the terminals o the base plate, with the use of a consistent color scheme. Use of yellow terminals for input voltages v1 and v2 and a white terminal for output v0 was necessary. The power supply was then set up with each workstation in the laboratory equipped with a Rohde and a Schwarz HMC 8043 triple-output power supply. Each channel, since it’s adjustable, was adjusted for 0v to 32v accompanied by a 3A, maximum current. The linking of the positive terminal of one channel to the negative terminal of the other terminal was necessary for the practical. Two of the outputs was used to provide a negative and a positive supply of 12v. NB/ it was ensured that nothing was connected to the output terminal of the power supply. (Huijsing, 2005) The power button was then turned on by pressing the button labeled POWER located in the lower Conner of the front annul. The display showed the setting of all the three outputs with the voltage on the left and current on the right. The current that was shown had the maximum availability for the channel. The CH1 button was pressed, and a soft menu appeared. The soft key labeled VOLTAGE was pressed, and the voltage for channel one was then varied with the use of the up or down arrow on the navigation control. It could also be done by turning the rotary control. The individual digits were selected using the left or the right arrow on the navigation control. Adjustments were made of the voltage to read to 12v on display. Therefore the rotary control was then pressed as a confirmation measure. The CH1 button was pressed, and a soft menu appeared as on the soft key the CURRENT key was pressed. The maximum current which is also termed as the current limit was varied by the use of the up and down arrow on the navigation control, and also either by turning the rotary control. Individual digits were again selected with the utilization of the right and the left arrows on the navigation control. Adjustments on the maximum current were made to read 0. 1 A on display , then the rotary control button pressed for the confirmation of the digits. The CHI button was put ON and off despite the fact that it is illuminated. The output was found to be active still. Therefore the same procedure was repeated to the CH2, so for it to be set to have +12 v, 0.n 1 A, and to be ON. The MASTER was pressed ON and OFF. This activated the 1st and the 2nd channels thus the current display showed the ACTUAL current flowing rather than the maximum current that can be available. The MASTER button is turned ON and OFF again to isolate the output until it was needed again. The power supply up to this far was successfully set. The power supply was the connected to the breadboard using the special red, black and blue twisted wires, and observations recorded whereby the red equaled to +12v, the black equaled to 0v, and the blue equaled to -12v. The non-inverted amplifier configuration Figure 1.1.1 The feedback loop operating the output voltage of the op-amp reached a value at which only a zero value could cause the voltage difference between the negative and the positive input. (Hongervors, 2006) Therefore the A and the VA voltage nodes equaled to a zero. By the fact, and that when the current flow is at zero, the circuit flowed into the op-amp because of the infinite input impedance. Therefore the nodal analysis was applicable in the funding of the gain loop that was close, Acl which was equivalent to Vin/ Vout. The calculations were as demonstrated below. Given that Vin was equal to VA, we got: After Re-arranging the equation aw got: On adding Vout / R2 to both sides and re-arranging gave us: Dividing through by Vin we got: Multiplying both sides by R2 gives: Finally, the RHS equations were combined, and when set to be equal to Acl, it gave the following equation: Therefore the analysis showed that the gain was positive and that the values could be set by the circuit designer when he carefully selected the R1 and the R2. The inverting amplifier configuration In the inverting amplifier, the positive input terminal was connected to the ground with the Volt being at zero. The virtual concept of the earth was applied with the feedback loop that was negative in the op-amp place being able to adjust the voltage of the output, Vout, to a value that brought the deviation between the input voltages to zero. (Gray, 2012) Change in Vout caused the terminals of the negative input connected to the "A" node whereby it came to an energy that matched the zero volts to the terminals which were positive. The condition at Node a was termed as the virtual earth since the op-amp set no physical connection to the connection to the ground to the potential ground. The diagrammatic presentation of the practical was as follows: Discussion Intuitively, the current Iin and the If were easily seen with the infinite input impedances are equal in magnitude with If given a negative symbol as a way of showing that the flow if moving out of the node A instead of moving out it moved out in the In.’s case. It was clearly seen that as the prevailing currents flowed from the positive terminal to the negative one, the op-amp was supposed to take the Vout to a negative value thus bringing the If to stem from the A node during the matching of the values of the input. (Kaulberg, 2013) This was used to explain the action of insertion of the configuration. The clear understanding of the flow was also proved mathematically. The current laws of Kirchhoff were applied in the analysis of node A. With node A being at zero volts this was simplified to: On rearrangement, we got: Therefore on dividing the Vout by Vin, the ratio resulted was the circuits' "real gain." It was then called the loop gain which was closed and was expressed as Acl. It was also evident that the increase of the configurations was dependent on the R2 and R1 ratio and that the designer of the circuit had made the best choice of the loop gain that was closed of the amplifier through his selection of the resistor values which were suitable. The final equation that was settled for was: The summing of the noninverting op-amp's configurationAs shown below, the summing of the non-inverting op-amp's configuration had two voltage sources. The operating amplifier's tension with the loop of feedback operating there reached a value that reduced to zero the difference between the negative and the positive inputs. Therefore, the voltage at node A, and VA got to be equal to the voltage when the voltage was at the positive terminal. Also, the V+ whose connections was to the B node and the node between the two resistors got to the zero value. On application of analysis of note at node B gave the following results: Multiply through by R and addition of V1 and V2 to both sides gave: On Diving both sides by 2 and equating VA and VB there yielded: On the usage of the same resistor’s values in series together with the sources of voltage would result in VA, thus taking the mean value of the sources’ voltage. It was useful when we did set different gains for each of the sources through the usage of differentiated resistor values. The easiest approach to the determination of the Vout gave VA as I used the divider equation which was possible.The potential divider that was formed by R1, R2, and the Vout was as described below: Re-arranging for Vout gives: And substituting for VA: The summing of inverting op-amp On analyzing the circuit, it was simplified by replacement of the input networks on the input inverting by the EQUIVALENT CIRCUIT BY Thenenin. The simplifications used are as indicated below The Thevenin equation of network input the complete circuit with the thevenin equivalent input used is as shown below. There was another theorem called the "superposition theorem" that was used in finding the value of VTH. The VTH value was described as the voltage of an open circuit that was to be measured between the B and the A nodes. (Klinke, 2009) If v2 was deactivated, the difference in voltage between the A and B as well as the VTH were found by the usage of the potential equation of dividing. When V1 was deactivated, the VTH was found to be in the same way as it was. Therefore the VTH’ and the VTH’’ sum was expressed mathematically as worked out below Which was the simplified into the following: (3) In the finding of the Thévenin resistance RTH, the strength was measured in the range between a and b with de-activation of all sources. It was clearly seen that it all resulted in the active resistance of R1 and R2 in parallel. Conclusion The session showed that there was the requirement for additional power supply which could be the input v1 and v2. This was to be provided by the Schwarz and the Rohde HMC 8042 dual-output power supply, and this had two output channels which are adjustable from zero to thirty-two volts. Turning on the supplies and setting the output from 0v and 0. 1 A as described in the procedure. These Rohde power supplies are said to have a digitalized voltage and current display Reference Gray, P. R., & Meyer, R. G. (2012). MOS operational amplifier design-a tutorial overview. IEEE Journal of Solid-State Circuits, 17(6), 969-982. Huijsing, J. H., & Linebarger, D. (2005). Low-voltage operational amplifier with rail-to-rail input and output ranges. IEEE Journal of Solid-State Circuits, 20(6), 1144-1150. Hogervorst, R., Tero, J. P., Eschauzier, R. G., & Huijsing, J. H. (2006). A compact power-efficient 3 V CMOS rail-to-rail input/output operational amplifier for VLSI cell libraries. IEEE journal of solid-state circuits, 29(12), 1505-1513. Kaulberg, T. (2013). A CMOS current-mode operational amplifier. IEEE journal of solid-state circuits, 28(7), 849-852. Klinke, R., Hosticka, B. J., & Pfleiderer, H. (2009). A very-high-slew-rate CMOS operational amplifier. IEEE Journal of Solid-State Circuits, 24(3), 744-746. Read More