@Stefan Schippers or anyone can please suggest me i am trying to get the current of 50 micro amps i have marked in the picture for that i tried to increase the W and L also it did not work can you please suggest how can i increase the current to get output i have attached the circuit of controller ,switch and graph

I don't understand exactly what your circuit is. Is it an analog mux? What is the load? I'm only seeing a voltage sources at the inputs. How do you plan to make a current out of this?

Yes I am using voltage source at input and demux is digital and switch is analog and input to the switch is analog For that I have used level shifter I wanted to measure the current at output

If the input is, let's say, 1 V, and you want 50 uA at the output, you would need 20 kOhm at the output of the switch, connected to gnd. I'm not sure what you're using as the load of your circuit.

"I used a resistor as a resistive load to ground. To measure the current, I placed an ammeter in between. I'm trying to switch lines using a demux and using the analog input to CMOS gates so that one output will follow the analog input and the other will be zero. The resistive load has been used to ensure the upper operation is correct. I want to know how I can get a high current output. Is it possible to achieve this by increasing the cmos gate size?"

First of all, you need to check the voltage drop in your switch. It should be really small. What is happening there? You should try to design your switch alone first, then see what is happening. 50 uA is really a very small current for a transistor to work as a switch.

@Rafeeq Khan Mohammed I have not gone through the details of the circuit, however, please do not name an I/O port of a subcircuit to 1.8. Use V1P8 or V1_8 or whatever that is a valid identifier. May be ngspice accepts this port name , but let's stay on the safe side.

@Luis Henrique Rodovalho @Stefan Schippers Thank you