Canon whitepaper "Advances in CMOS Image Sensors and Associated Processing" by Shin Kikuchi, Daisuke Kobayashi, Hitoshi Yasuda, Hajime Ueno, and Laurence Thorpe, first presented at the Hollywood Professional Alliance (HPA) Tech Retreat in Palm Springs on February 19, 2016 talks about challenges in 19um large pixel design (note a strange definition of conversion gain, probably meant to be image lag):