McMullan submitted his resignation due to personal reasons, the company said, and his resignation "is not the result of any matters related to Macom's's financial statements or disclosures or accounting principles and practices."
The company also announced that Conor Hegarty, vice president of financial planning and analysis, has been appointed to the role of principal financial officer and principal accounting officer, effective immediately.
Hegarty has been with the company for 22 years and has served in his current role since 2016.
"On behalf of the board of directors and the executive team, I would like to thank Bob for all of his contributions at Macom," said John Croteau, president and CEO. "During his tenure, Bob was instrumental in rebuilding and reshaping MACOM through numerous acquisitions and divestitures, as well as corporate financing transactions. We are grateful for Bob's positive impact on the company and wish him continued success in his next endeavor."