Many semiconductor stocks rallied strongly over the past year, fueled by robust demand for chips across various industries. That's why the Philadelphia Semiconductor Index advanced 32% over the past 12 months, easily beating the S&P 500's 14% gain.Two strong performers in that sector are NVIDIA (NASDAQ: NVDA) and Cypress Semiconductor (NASDAQ: CY), which rallied 75% and 35%, respectively, during that period.