We propose and demonstrate a vision chip that can detect eye-safe light by using SiGe heterobipolar transistor process. This process realizes monolithic integration with an eye-safe heterophototransistor(HPT)and CMOS circuits. The responsivity of the HPT is simulated and is found to have enough sensitivity in the eye-safe region. To employ the HPT in a vision chip, we design a test chip with pulse frequency modulation circuits, which has a wide dynamic range without accumulation action. The chip designed using 0.35μm CMOS 2P3M process works well under a power supply of 0.7V and has a dynamic range of 20dB and a power consumption of less than 1μ W. Also mutual inhibition is implemented in the chip to realize elemental image processing function.
