Interdigitation question

Status
Not open for further replies.

AMSA84

Advanced Member level 2
Joined
Aug 24, 2010
Messages
577
Helped
8
Reputation
16
Reaction score
8
Trophy points
1,298
Location
Iberian Peninsula
Visit site
Activity points
6,178
Hi guys,

When doing interdigitation, the first diffusion is better to be the source or drain? Because of the capacitances.

I am doing a layout a differential pair. I can split him in 4 or 5. If I split in 4, each finger has 5um and I can do a interdigitation pattern as: AABBAABB or ABBAABBAAB. The first pattern starts with SOURCE, the second with DRAIN. The axis of symmetry for the first pattern is different for the transistor A and B and the axis of symmetry for the second one is the same.

Kind regarsd.
 

It depends if you need better common mode rejection or better bandwidth. Reducing capacitance at the sources extends the bandwidth of the common mode rejection, reducing it at the drains it helps to push parasitic poles (or dominant poles if that is the case) to higher frequencies.
 

Status
Not open for further replies.

Similar threads

Cookies are required to use this site. You must accept them to continue using the site. Learn more…