Hi,

I assume that you are referring to the Ahuja compensation (Ahuja, B., JSSC, Dec. 1983) when you say "cascode compensation", and the lead compensation involves using a MOS transisor in triode to realize a series compensation with an R and Cc (by Tsividis I believe).

From my experience, I can list the following pros and cons:

1. Ahuja compensation:

+ Breaks the feedforward path completely, gives excellent phase margin
+ Owing to above fact, compensation relatively independent of process etc.
+ Easier to design
+ Good PSRR at high frequencies
- 1 extra stage (level shifter)
- Systematic offset introduced, since the tail of the level shifter is tied to the output of first stage
- Slew rate of opamp affected by current flowing in the intermediate stage as well

2. Lead compensation (assuming a good MOS implementation as described in Johns & Martin):

+ Good phase margin, but less than what one would get from the former approach.
+ Fairly good control over process variation etc. when the gate bias of the compensating device generated properly to ratio with input Gm
+ No extra stage (less current consumed)
+ No systematic offset
+ Slew rate should not be affected
- PSRR worse, and similar to that of a standard Miller compensated stage without R
- 1 extra pole (Other scheme also introduces an extra pole, but typically at a much higher frequency)
- Slightly harder to design (Ahuja compensation can be made to work first time even by a novice)

Both schemes will add extra noise, and a good comparison on this point eludes me.

I prefer the lead compensation scheme in most cases, although I feel that the first approach is much more elegant and simple.

Regards
Vivek