Question

a. (10 pts) Implement the voltage amplifier shown below using an ideal op amp circuit. You have one op amp available for this circuit, and a range of resistors with values from 1 kΩ to 100 ka. Draw the schematic of your op amp circuit, labeling resistor values. Make sure the gain, input resistance, and output resistance of your circuit matches the model in the schematic. R=012 *100v, RL 100 b. (5 pts) Your amplifier circuit should have a frequency response where the gain for f2 10 GHz decreases by 20 dB/dec. Calculate the required unity-gain bandwidth of the op amp. c. (10 pts) The available has a maximum output current of +0.3 mA, a maximum output voltage of t1 V, and a slew rate of 169 V/us. Will any of these specifications have an effect on the output signal of the op amp if you use an input signal that is 0.2 mVms at f- 1 GHz? If so, what will happen to the output (describe qualitatively in a sentence or two)? Is this particular op amp a good selection? If not, what specification needs to be improved?

Answer 1

(a) RF 99kn R lkn RL 1002 Va Figure 1 Figure 1 shows a low pass filter. At low frequencies where Capacitor C is an open circuit, the magnitude of the voltage gain is limited to the value 1 Rr A1+ 99k 1+ lk - 100 Output resistance, R 0 , Input resistance (b) As gain reduces by 20dB/dec, at f <10GHZ , hence it is the cut-off frequency wwww. -201B/dec R 20 log A B.W fc

Cut of frequency is, 1 RC 1 10x10 1x10 C 1 (10x10)(1x10) X X C 0.1pF Hence, C 0.1pF The gain bandwidth product op-amp is, GBWP Ax fe 100 x 10x10 1x1012Hz 1THZ Unity- gain bandwidth is the bandwidth of the op-amp at which that gain of the op- amp falls to unity GBWP AXBW 1x 10 1x BW BW 1x1012Hz 1THZ (C) Maximum current voltage and slew rate is, Iur 10.3mA, V a MAr SR 169 V/us For maximum output voltage of 1V, the input signal would be, Vo- A 1 V, 100 1mV

SR 2Tf V, =27T x 10 x10 x1x10 MAY 628.3V/us Hence, the slew rate required to amplify the maximum input of voltage 1mV is, 628.3V/uS and the slew rate is provided as 169 V/usS, hence the slew rate require is sufficient enough The required slew rate is much below than the slew rate of the op-amp hence, no modification in the circuit is required With the input signal of, 0.2mVG the required slew rate is, m f-1GH SR: 2πfV 27T x1x10 x0.2x v2 x103 X 1.77V/us Hence to amplify input signal of V 0.2mV the output of the op-amp must change by 1.77V/us, and the slew rate is provided as 169 V/us, hence the slew rate require is not sufficient enough, and output obtain will be distorted. Hence this op-amp is not a good selection for it as it is the only To obtain desire result frequency of op-amp could be changed variable which could be changed.