I'm designing a full-wave precision rectifier using OP07 in LTSpice. The first stage of the circuit (shown below) buffers the AC input using an OP07.
But the buffer output is clipped with a significant DC offset at 10 V input when the peak of the non-inverting terminal input is approximately 1.6 V: Buffer output for 10 V input
The buffer output is also clipped at 2 V input when the peak of the non-inverting terminal input is approximately 0.5 V, with the output waveform distorted: Buffer output for 2 V input
Both these non-inverting terminal voltages are below ±VDD. I observed a similar behavior on replacing the OP07 with the MAX4352.
Of course, the circuit with the OP07 replaced by a universal opamp - a single-pole opamp with no limits on output voltage swing - exactly buffers the input as expected, without any offset or clipping for both 10 V and 2 V inputs. Universal opamp buffer output for 10 V input
Why are MAX4352 and OP07 buffer outputs clipped and offset even though the non-inverting terminal voltage does not exceed ±VDD?
EDIT: As periblepsis and Andy aka pointed out, I messed up with the supply connections. The circuit now works as expected: enter image description here
-
\$\begingroup\$ Isn't your +Vdd just 0 V? \$\endgroup\$periblepsis– periblepsis2023年09月30日 12:54:53 +00:00Commented Sep 30, 2023 at 12:54
-
\$\begingroup\$ Ahh, indeed it is, I missed it somehow. \$\endgroup\$Kartik– Kartik2023年09月30日 13:10:02 +00:00Commented Sep 30, 2023 at 13:10
1 Answer 1
You have set-up your op-amp power supplies incorrectly. V2 positive is tied to ground and, of course V2 negative is at -12 volts but then, for V1, you have its negative terminal connected to -VDD when it should connect to ground: -
Alternatively leave as is but change V1's voltage to be 24 volts.
-
\$\begingroup\$ Oh no, I missed checking the supply somehow. Thank you for pointing this out! \$\endgroup\$Kartik– Kartik2023年09月30日 13:08:53 +00:00Commented Sep 30, 2023 at 13:08