Analog Circuit Design Laboratory Report - MyWeb at WIT ...

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Figure 3- Inverting Amplifier The closed loop finite gain, ACL, is possible when the input resistance and the negative feedback resistance are connected between the output and the inverting voltage source. From a virtual ground created by the sensed difference between the op-amp’s inputs, a node equation can be made based on Kirchoff’s Current Law, as stated below: All currents entering a node equal the sum of currents leaving a node. From this equation, the feedback resistor, Rf, acquires a current with equal and opposite value of the current across the input resistor, Rin, driven by the input source. Only these two currents are involved in the node equation because the inverting input pin takes no current due to its ideally infinite resistance. The current across Rin and Rf must then be equal. Because of the virtual ground VO is equal to the voltage drop across Rf. Therefore the ACL can be written as shown in Equation 7. The gain is a result of negative feedback. A − R = Eq. (7) f CL Rin 8
The non-inverting amplifier works similarly to the inverting amplifier. The non- inverting amplifier has a different negative feedback loop by removing the source at the inverting pin. Thus changes the direction of the current across Rf, see Figure 4. Figure 4- Non-inverting Amplifier The inverting pin, now grounded, allows for Rin current and Rin voltage to be determined since a virtual ground is created with respect to Vin and an Ed of zero. This is also due to the inverting pin taking on no current due to its infinite resistance. The Rf current can then be found from Kirchoff’s Current Law because it is the only other current involved with the known current at Rin meeting at the virtual ground node. The direction of current flow there shows RF supplying the current to Rin. The gain equation for the non-inverting 9
Page 1 and 2: EVALUATING OPERATIONAL AMPLIFIERS I
Page 3 and 4: The ideal op-amp generally has 5 te
Page 5 and 6: ended output voltage Vo is equal th
Page 7: Negative feedback occurs when the o
Page 11 and 12: In association with the non-inverti
Page 13 and 14: Figure 7- Instrumentation Amplifier
Page 15 and 16: favorably both voltages being withi
Page 17 and 18: The next configuration, with a 10-k
Page 19 and 20: Figure 11- Positive Isc at approxim
Page 21 and 22: Figure 13- Plot of Ei versus time a
Page 23 and 24: Using the information derived from
Page 25 and 26: The output voltage can be altered s
Page 27 and 28: Analysis of an Inverting Amplifier
Page 29 and 30: 180º phase shift from the Vin. The
Page 31 and 32: The oscilloscope had the input volt
Page 33 and 34: Voltage (V) 8 6 4 2 0 -2 -4 -6 -8 F
Page 35 and 36: Voltage (V) 6 4 2 0 -2 -4 -6 Figure
Page 37 and 38: could be reduced to 1-kΩ. To decr
Page 39 and 40: The 10-kΩ potentiometer was then
Page 41 and 42: input stage VO’ was calculated to
Page 43 and 44: Adding Vref to an instrumentation a
Page 45 and 46: 1851g 4 lbs. 19.74 mV 2268g 5 lbs.
Page 47 and 48: Roff was calculated to be a 1.2-M
Page 49 and 50: Through the use of negative feedbac

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