Conn. Gen. Stat. § 33-711: Greater quorum or voting requirement.

(a) The certificate of incorporation may provide for a greater quorum or voting requirement for shareholders, or voting groups of shareholders, than is provided for by sections 33-600 to 33-998, inclusive.

(b) An amendment to the certificate of incorporation that adds, changes or deletes a greater quorum or voting requirement must meet the same quorum requirement and be adopted by the same vote and voting groups required to take action under the quorum and voting requirements then in effect or proposed to be adopted, whichever is greater.