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Because Vds voltage is almost zero..
Because Vds voltage is almost zero..
Your Mosfets are drawn with 4 pins instead of the normal 3 pins. Then we cannot see which is drain or source.
Your supply voltage is not shown. If it is low then the P-channel Mosfets are turned off and they are the loads for the N-channel mosfets so of course the current is very low.
The original circuit is "working" as well. The question is what you want to achieve.
Believe me, tweaking your circuit like this is not the best practice.
Your first circuit works as well. It's much better to have a current mirror as a load in your differential stage.
If you want to get more help from us, you should give further information such as: VDD, threshold voltages and aspect ratio of mosfets (at least).
The main issue is M14 drain and gate stuck at 3.294V therefore M14, M15 current load off. No current flowing.Look, in your first circuit you are tying the gate of M18 to VDD.
In principle, this is not the correct way of biasing because you want M18 to behave as a current source and create a virtual ground for balancing the current at each branch.
Basically, what you are doing is dropping the drain terminal of M18 to ground, so there is no Vds, then it operates in the linear region and not in saturation and the rest of your circuit is not operating as a consequence of this.
What you can do is to put an ideal current source, set the proper value (you need hand calculations for that) and mirror this current to M18.
This is the correct way of biasing since you ensure that your differential pair is drawing the current set by your current source and so you don't have floating nodes.
The main issue is M14 drain and gate stuck at 3.294V therefore M14, M15 current load off. No current flowing.
If I could solve when M16 gate at 0 V, M14 drain and gate would not be at 3.294V and be near 0 V.