opamp simulation

[zxcv2201]

I am trying to simulate an op amp made by OTA. The result comes out correctly only when the tail current is not entered. When checking the dB20, phase results of the Opamp, I wonder if I should put a bias or not.

If it's ok without the bias, I wonder what the reason is.

 

[FvM]

I guess it's the circuit.

 

[BradtheRad]

I guess a current source started out as your tail current. Set its Ampere level so the output is at a midway volt level (as though building a class A amplifier).

Apply input signals to the bias terminals. Set input average level centered on 0V.

Start with small signal amplitude, say a few mV.

The current source creates a negative polarity supply rail. Thus you have a bipolar power supply as normally specified for an op amp.

Observe output. It should behave as a differential detector.