Nandan Nilekani has been appointed as its new chairman of Infosys , replacing R Seshasayee. He is former CEO and Aadhaar-architect.Ravi Venkatesan also resigned as co-chairman, but will continue as an independent director.Vishal Sikka, who quit last week as CEO but was made vice-chairman till his successor was appointed, also quit the board with immediate effect, the company said in a statement after its board meeting.Two independent directors Jeffery S Lehman and John Etchemendy also resigned from the Infosys board with immediate effect.