Mixer(gilbert cell) Gain problem
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
8117547.plt.pdf
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.
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
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 ----------
But I don't have TSMC 0.18 PDK
I change loads to 0.5Kohm
in this case, I_Proble1=1.217mA
[IMG][/IMG]Temp?11.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
Can you please to post the Spice Netlist, i am in great need of it.
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]))?