some of you probably remember my last question, but I like to reiterate: I created a bandpass filter with the help of the online tool FilterWizard, which should block below 30 kHz and above 300 kHz; the whole thing with ± 9V supply voltage and 3dB gain in the pass band. In addition, it has been optimized in the direction of Low Noise.
Under the ‘Voltage Range’ tab on the website, it is stated that the signal may range from -8.25V to 8.75V.
As you can see in the schematic created by the online tool, there is an AD8022. Since I use PSpice for TI 2021.1, I “only” have the components from Texas Instruments. I searched back and forth for a long time until I found a (apparently) suitable operational amplifier. I entered the specifications of the AD8022 (slew rate, gain bandwidth, Voltage Offset, Voltage Noise) on the Texas Instruments website and found and installed the THS4021. I've also tried others before. The problem is that no matter how good the op amps are on paper, the simulation always results in nonsense. I have already cross-checked whether I made a mistake in the schematic. What's going on?
This project is for training purposes only – I am not a qualified electrical engineer. Unfortunately I cannot offer you an .asc file.
Analog Filter Wizard – planned Magnitude
Analog Filter Wizard – given circuit
Analog Filter Wizard – Voltage Range tab
my circuit (jointed image)
Simulation: red curve: Voltage Source; green curve: VOut
Edit: Attached is a picture with graphs of what components R3, R5 and C7 see at their input.
Edit 2: While everything is ok on the left side of the C7, ‘Node N02220’ (orange line) sees this… .
Edit 3: I have now reduced the voltage to a tenth. This seems to work to me, except that from around 250kHz the amplitude of VOut is no longer as large as it should be up to 300kHz.