We present a CMOS computational camera with on-chip compressive sensing technique. Through per-pixel programmable charge modulation, camera exposure is spatial-temporally encoded by a CMOS image sensor without utilization of superfluous optical modulators. Each sensor pixel incorporates a two-tap charge modulator and exposure code memory cells, and a proof-of-concept image sensor (128×128 pixels) is capable of per-frame spatial-temporal coded exposure in either full resolution or designated region of interest. After reconstruction, high-speed videos at various temporal resolutions are recovered, while the prototype camera operates at 10 fps. Comparing to previous works, this camera design provides a power-efficient solution for compressive sensing related applications.