SUB connection in Pipelined ADC

[codec]

Should I separate SUB to a dedicated PAD in Pipelined ADC design?
If separation is necessary, should how to deal with the SUB of digital part?
Thanks!

 

[sunking]

it is better to connect the SUB to a dedicated PAD.
And it is also better for dedicated PAD with the SUB of digital part

 

[Btrend]

this is a question always there.
1. if u do test chip , u can try two type of connections
2. if ur ADC is integrated in SOC, usually pad is insufficient, u should consider again.
3. if body effect affect ur ckt, especially those cascode amp, u had better connect SUB to near GND first. otherwise ur output swing maybe limited by the cascode mos.