hello everyone! below there is a circuit that i took some help from Franco's operational amplifier design book, as u can see i got a gain around 3 from the 20k/(20+11k) resistors. but when i increase the 20k resistor to have a higher gain, i got my output sinusoidal waveform like noise signal. As i heard from the Franco's book, the RC values (158k, 1nF) are designed to have a correct sinusoidal waveform around a 3 gain circuit. i have posted the oscilloscope screenshots below also, anyway i need help on this circuit to set the max. gain around 50, when i got the 20k to 490k i got a distorted signal looks like nothing. I didnt have any knowledge on amplifiers without an ac input, as i understanded from the book, this circuit creates its own ac input and amplifies it. Thanks for the help from now.
NOTE: 2nd pic is the output signal V2, 3rd is the input V5... thanks
NOTE: 2nd pic is the output signal V2, 3rd is the input V5... thanks
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