Mixer(gilbert cell) Gain problem

[laperla]

Hi
I really really need to help. I don't know what I do for my project...
My gilbert cell has negative gain I can't improve it
can somebody help me to improve my project?
plzzzzzzzz
View attachment 8117547.plt.pdf

 

[BigBoss]

W=44um, L=0.18um and Vgs=1.6V (less than)..
The drain currents will be very high and there won't be sufficient voltage headroom to be swung...
Check the drain currents
What about the load ?? If you terminate simply 50 Ohm, the gain will be very low and check the differential LO swing between the gates of switching MOSs by transient analysis.

 

[laperla]

thanks for replying
I_Probe1=1.129mA
I_Probe2=2.258mA

---------- Post added at 21:39 ---------- Previous post was at 21:36 ----------

can I give u my project and you edit it?
I really confuse:!:

 

[BigBoss]

thanks for replying
I_Probe1=1.129mA
I_Probe2=2.258mA

So, 1.129mA x 1kOhm=1.129V drops across the drain resistors.
The voltage headroom is 1.8V-1.129=0.671V .. This is too low for 2 MOSFETs.( 0.3V for each maybe less)
The MOSFETs are working probably linear mode.If we consider Vds(sat)=0.05V, the peak-to-peak swing at best case will be 1V at open circuit.
If you terminate the load with an low impedance, this swing will be much less...
Make a transient simulation and check the differential LO drive level at the gates.It might be low to drive..

---------- Post added at 22:51 ---------- Previous post was at 22:49 ----------

thanks for replying
I_Probe1=1.129mA
I_Probe2=2.258mA

---------- Post added at 21:39 ---------- Previous post was at 21:36 ----------

can I give u my project and you edit it?
I really confuse:!:

But I don't have TSMC 0.18 PDK

 

[laperla]

I change loads to 0.5Kohm
in this case, I_Proble1=1.217mA
View attachment Tempæ11.pdf
also in the other simulation I replaced R with LC but I couldn't give high gain and always the gain was low and negative

 

[kalidasascreator]

Can you please to post the Spice Netlist, i am in great need of it.

 

[laperla]

Hi my friend

I did that project but I need to draw the IIP3 ( input v.s output power) in ADS
in simulation page,, I have to use dbm(out([::1])) and dbm(out([::3]))???