As far as I know, that specification was never revealed.
There is no absolute set standard for chip sizes; the HVX200's chip is a little bit bigger than the one in the JVC HD100, and a little bit smaller than the one in the HVX200A, but they're all classified as 1/3".
If you want a "ballpark" estimate, it's somewhere around 4.8 x 3.6mm. But I don't know what the exact measurements are.
