common source amplifier gain
Hi Denis,
Thanks,
here is my design spec.
Prcess :180nm
type : CS amp with active load
GBW= 50meg, Cload=1p, gain=~5, vdd=3.3
I have chosen (gm/id)nmos =10 corresponding id/w = 3.229 both values are for L=1u, Early voltage =71.3
(gm/id)pmos = 5 corresponding id/w=2.53 both values are for L=1u, early voltage=68
i calculated operating current frm this equation
GBW=(gm/id) x (id/2 x pi x Cload) and its value is 31u
but my simulated results are
gain=10, 3db bw=19meg, Id=48u.
as per the early voltage values my gain shld be around 340 (gm/id)nmos x vea_eff
please correct me.
othr question,
1. how to choose gm/ids for nmos & pmos connected in series, As they have different mobility but will have same current.
Please let me know if i m not clear
Thanks,