Lab Report Operational Amplifier Application Essays

Lab Report Operational Amplifier Application Essays Lab Report Operational Amplifier Application Paper Lab Report Operational Amplifier Application Paper In this report, we Will go through two experiments, Which are the fundamental circuits of operational amplifiers: non-inverting and inverting amplifier circuits, to analyze the difference between ideal and real pop-amps. For the following section, the relevant theory will be introduced, and then the detail and results of the experiments Will be discussed before proceeding to conclusion. Theory Figure 1 The pop amp and its ideal attributes As the Figurer shown, operational amplifier has two inputs labeled (+) and (-) with positive and negative power supply, and a single output. It is primarily a sigh gain differential amplifier which amplifies the difference tot voltages been two inputs. The output voltage of the amplifier Bout is given by the following formula: Bout = A (VT V-) Where A is the open loop voltages gain of the amplifier, which typically is very large about ISO at low frequency. And V- are the non-inverting and inverting input voltage respectively. From the equation, output voltage is entirely governed by the difference between the two input voltages. However for real pop-amps inputs do draw a small amount of current and the output voltage is affected by the output current drawn. Poor the analysis, both inverting and non-inverting amplifiers are applying negative feedback. It cause the V- to increase, hence voltages Of the two input terminals Will be much closed together. And the input draw current is assumed to be zero. Therefore Kerchiefs first (current) Law and Kerchiefs second (voltage) Law could be applied. Experiment The main apparatus for this experiment are the test board with TLS power supply, Kingwood ACCESS oscilloscope, Homage DVDs, and the input signal function generator is Homage HM80030-2. Inverting amplifier: Bout=-RFC Vein Inverting amplifier: Figure 2 Inverting Amplifier Constructing the circuit of an inverting amplifier as shown in figure 2 on the test board. In order to make an amplifier with a gain of . 10, setting RI 2. 7 k and RFC = 27 aquaplaning a Homage signal generator, a KHz sine wave was supply into the amplifier input, the amplitude should be adjusted to low values to prevent waveform distortion occur. Moreover, connecting the input and output of amplifier to X-Y channels of the Oscilloscope, to check the waveform and verity the amplification, If both inputs are held at a common zero, the offset voltage will not be zero as deadly owing to a small amount of bias currents and internal imbalances of a real amplifier. Setting the oscilloscope to X-Y mode, a graph like Figure 3 will be display in the screen. The output offset voltage which is the sum of two independent variables, one is Input offset voltage (Vein offal the other one is input bias current (In bias ). The equation of the Bout off is given below: Bout off=Vein offal+RFC+line bias RFC For the experimental purpose, the values of RI and RFC should be varied to form simultaneous equations, as a result, Vein Off and In bias could be derived separately. When applying RI = 2. Non and RFC = kick , the value of offset voltages Obtained was urn: furthermore, the value Of Bout Off increased to I Iron While RI = 0. Aka and RFC = Aka. Hence the simultaneous equation could be solved: offshoot 2. K*line bias ask Vein off= 0. 916 NV offal bias ask In bias 06. 92 an Figure 3 WY mode trace of Bout against Vein With the respect to Figure 3, the values foeman and Vein acquired from experiment are and -1 IV, therefore the real output voltage range is from -IV to +13. IV when  ±IV supply rails are being used. Additionally, two horizontal nines reveal that maximum and minimum output voltages will less than the supply rail voltages due to the energy losses in the internal resistors. Figure 4 Measurement of the output impedance Measure the output impedance of the inverting amplifier by setting input voltage to ground, and injecting a load current to output side by adding a signal generator which drives a 10 kHz sine wave via a 2200 resistor. Compare the difference between V out and V load shown in figure 4 by applying the oscilloscope, so that the output impedance could be derived by following equation Output impedance: V outlet here lout=(V load- V out)220 As the result, the value Of output impedance obtained from experiment is I . Q, which is quite small but still not equal to zero as ideal situation. In addition to this, V out Will rise when the frequency Of the signal is increasing; Meanwhile, the closed loop output impedance Will tend to zero. Because the deviation between the V out and V load is getting smaller. Inverting amplifier: Bout=1+Riving Non-inverting amplifier: Bout= 1 Vein Figure S: Nan-inverting amplifier Converting the circuit in to non-inverti ng amplifier and using the same values of RFC and RI ,Moreover, applying the signal to the positive input of pop-amps, thus a positive gain can be acquired Much more interesting, the output offset voltage and output impedance will stay the same as values obtained from inverting amplifier. The reason is the resistors for both circuits are consistent. Discussion Prom the investigation Of the experiments, the gain Of non-ideal amplifiers is finite and it could be affected by the changing in frequency and existence of input Offset voltages. Experiments have shown that there is error input voltage due to the non-zero bias currents flowing in the input terminals. Also they have proved that the maximum gain Of real pop-amps is finite and limited by maximum and minimum supply voltages. During the experiment, it is vital to be aware of the error that may occur. Generally, errors can be divided into tuft categories which are the systematic errors and random errors. Unfortunately, systematic errors are unavoidable because of the existing error in the equipment used in the experiments. For instance, homage DVDs can accurate about 0. 1% for DC voltages and 0. 2% for resistance; the accuracy of AC signals is around 1% while the frequency is within angel from GHz to kHz. However,the random error could be minimized to the best extent by taking several measurements and using the average values. Conclusion The results acquired from the experiments reveal the properties of both inverting and non-inverting amplifiers, and describe the differences between real and ideal pop-amp Further, the phase relationships of input and output voltage for the inverting amplifier are 180 degrees out of phase; as opposed to this, they are in phase with each other for Nan-inverting amplifier.