swolf
Newbie level 6
I am designing a folded cascode OTA for pipelined ADC. It requires 400M Hz GBW with lowest power consumption. the load capacitance is fixed (i.e. 4 pF), so i need to design the input MOST to get the largest gm under the lowest id of the input MOST.
as we know, gm is inversely propotional to (Vgs-Vth), the question is: what is the proper Vgs-Vth?
i designed the mosts and simulation result is:
#(0.18um process) the simulation tool is Spectre.#
w=300u, L=0.18u, Id=1.023mA, Vgs=558mV, Vth=470mV, Vdsat=118mV, Vds=1.187mV, gm=14.6mS, ron=1.16K
is this value (Vgs-Vth=88mV) proper? would it course some problems in reality? or can i still decrease the Vgs for more larger gm? what is the proper value in reality?
Would you give me some hints? Thank you in advance!
as we know, gm is inversely propotional to (Vgs-Vth), the question is: what is the proper Vgs-Vth?
i designed the mosts and simulation result is:
#(0.18um process) the simulation tool is Spectre.#
w=300u, L=0.18u, Id=1.023mA, Vgs=558mV, Vth=470mV, Vdsat=118mV, Vds=1.187mV, gm=14.6mS, ron=1.16K
is this value (Vgs-Vth=88mV) proper? would it course some problems in reality? or can i still decrease the Vgs for more larger gm? what is the proper value in reality?
Would you give me some hints? Thank you in advance!