A complemetary metal-oxide-semiconductor (CMOS) lock-in pixel sensor based on a current-assisted photonic demodulation (CAPD) detector is described. The CAPD detector provides high demodulation contrast and yields excellent photo-response. The prototype followed standard active pixel sensor (APS) architecture and was fabricated using a 0.6 um CMOS process from AMS. We obtained a near infrared (NIR) light responsivity of 0.26 A/W at 860 nm. The pixel exhibits demodulation contrast of nearly 100\% at low frequencies and above 90\% even up to 2 MHz. The phase response is linear up to 2 MHz, and even up to 10 MHz with the appropriate phase extraction equations.