Hello, this is not my circuit. but I'm playing with it, and I have some questions

hello. First, this is not my circuit. Second, I'm newbie student. I just started studying electronic circuit two weeks ago.

I'm just playing with this Circuit. just poking around.. I have some questions. can you guys help me?

in this case, I can see weird graph in oscilloscope. (channel B connected to 'c'in circuit and ground)

is this graph right? I thought this graph should look like sine graph...isn't it?

• Welcome to Stack Exchange. What do you expect the circuit to do? – Brian Carlton Nov 20 '18 at 2:14
• well, I thought this circuit is amplifier, so ... I think it should amplify my input voltage...and I just curious about that graph – Queen Ellery Nov 20 '18 at 2:16
• Try a 5 mV (or maybe 5 uV) peak-peak input, what results do you get? – The Photon Nov 20 '18 at 2:28
• The amplification of this circuit (an operational amplifier) is enormous – 100.000 or so. You had to apply external resistors to limit it. What you see is clipping (the tops of the sins are higher than the supply can deliver.) – Janka Nov 20 '18 at 2:30
• well, Thanks Janka. where do you recommend me to apply resistors? – Queen Ellery Nov 20 '18 at 3:14

1 Answer

Assuming 1mA thru the current source, split into left and right sides of the input diffpair, that 0.5mA making 'reac' be 52 ohms, the gain will be 15,000 / (52 + 52) or about 150X.

This answer has a similar circuit.

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