really? chopper? i would LOVE to see a chopper that did not inject more noise than natural 1/f! 1/f is the random dance of carriers, my friend.. it's tiny. what is reported as flicker is usually measurement inaccuracy, and you know what? that may count!
chopper? even the clock injection from the substrate would be bigger than 1/f!
i understand there is a strong trend towards switched cap. razavi can burn in hell for all i care, although switched cap does have it's place. this paper is minimizing OFFSET thru switched cap, not flicker noise.
OKGUY - my suggestion for you is to reduce flicker would be to increase bias current. swamp out the randomness with strong current flow.. >50uA? >2mA? how much flicker do you consider too much?
PS - the way a chopper minimizes offset is by flipping the + and - terminals of the op amp (or some equivalent) back and forth very quickly. if the op amp has +2mV offset, then half the time it seems like +2v, half the time like -2mV. Suck up the ripple with a cap, and it seems like you have near-0 offset.