impulse123
Newbie level 4
Hi All,
I have to design a PGA where 1st stage of my circuit is a folded casocde and second stage is a common source. There is a resistive feedback in my circuit .
I have to design it to meet the following specs
a) 100 Mhz 3db BW
b) SNR >= 70 db
c) Phase Margin >= 60 degree
d) IM3 at 20Mhz >= 70 db
e) IM3 at 100 Mhz >= 55db
f) Gain setting of -6db to 12db
I have designed them to meet all specs , except IM3 and SNR which is currently 60 db and 30 db at 20Mhz and 100 Mhz respectively. My SNR is 60 db.
I thought to use gain boosting to increase my loop gain. It increased my open loop gain from 60db to 100db.
However, It doesnt seem to have any considerable effect on IM3 and SNR.
Can anbody help me gain an insight into this? Aso, how can i improve my SNR and linearity.
I have to design a PGA where 1st stage of my circuit is a folded casocde and second stage is a common source. There is a resistive feedback in my circuit .
I have to design it to meet the following specs
a) 100 Mhz 3db BW
b) SNR >= 70 db
c) Phase Margin >= 60 degree
d) IM3 at 20Mhz >= 70 db
e) IM3 at 100 Mhz >= 55db
f) Gain setting of -6db to 12db
I have designed them to meet all specs , except IM3 and SNR which is currently 60 db and 30 db at 20Mhz and 100 Mhz respectively. My SNR is 60 db.
I thought to use gain boosting to increase my loop gain. It increased my open loop gain from 60db to 100db.
However, It doesnt seem to have any considerable effect on IM3 and SNR.
Can anbody help me gain an insight into this? Aso, how can i improve my SNR and linearity.