Nicholas' sister Marsalee (born 1962) was shot to death by her ex-boyfriend in 1983, while Nicholas was in graduate school. Nicholas helped his mother and stepfather—Marcella and Robert Leach—found Justice for Homicide Victims, Inc., a non-profit organization that supports the families of murder victims.

After graduating from UCLA in the 1980s, Nicholas worked at TRW in Redondo Beach, where he met Dr. Henry Samueli, his Future Business partner who also was a professor of engineering at UCLA. Nicholas later moved to PairGain Technologies in Cerritos, California, where he was Director of Microelectronics. He left PairGain in 1991 to start Broadcom Corporation with Samueli.

He received a Bachelor of Science degree in Electrical Engineering from the UCLA School of Engineering in 1982, after attending the United States Air Force Academy, in Colorado Springs, Colorado. Nicholas earned a master's degree in 1985 and PhD. in Electrical Engineering from UCLA in 1998. His doctoral advisor was Henry Samueli. His doctoral dissertation on "Architectures, Optimization Techniques, and VLSI Implementations for Direct Digital Frequency Synthesizers" became the basis for the development of the chip that launched Broadcom.

Nicholas married in 1987; he and his former wife Stacey, a former electrical Engineer, have three children, Brett, Matthew, and Shelby. Nicholas is now divorced and lives in Newport Coast, California.

Nicholas founded Broadcom with Samueli in the spare bedroom of Nicholas' Redondo Beach condominium in 1991. Each invested $5,000 of his own money to get the Business off the ground. They took the company public in 1998.

Nicholas retired from Broadcom in 2003, ostensibly to work on his marriage.

In 2004, Nicholas announced a $10-million gift to St. Margaret's Episcopal School in Orange County and the formation of a partnership with the University of California, Irvine Henry Samueli School of Engineering to explore the application of Technology to enhance learning. In addition, Nicholas provides St. Margaret scholarships to students from Santa Ana.

Nicholas established the first-ever American Heritage Bowl Game for Historically Black Colleges, co-sponsored by the Navy and Marine Corps. It was held in August 2007 at the stadium at Cal State Fullerton and broadcast worldwide on ESPN and armed forces networks.

Nicholas and other Broadcom executives were indicted in June 2008 for stock fraud and options backdating. At the same time, Nicholas was also indicted on drug charges. The charges caused considerable scandal, and were the subject of much speculation in the press.

Judge Cormac J. Carney threw out the stock fraud and options backdating charges in December 2009. The drug charges were also dropped in January 2010. The Judge, in dismissing the charges, accused the prosecution of a "shameful" campaign of witness intimidation aimed at securing unjustified convictions.