Reference voltage generator having noise cancelling function and CMOS image sensor using the same
The reference voltage generator may include a reference current generation unit suitable for generating a reference current based on a first power supply voltage and a first ground voltage, a current amount adjustment unit suitable for adjusting a current amount of the reference current generated by the reference current generation unit based on a second power supply voltage and a second ground voltage, and a reference voltage generation unit suitable for generating a reference voltage corresponding to the reference current, of which the current amount is adjusted by the current amount adjustment unit, based on the first power supply voltage and the first ground voltage.
1. A complementary metal-oxide semiconductor (CMOS) image sensor comprising:
a pixel outputting a pixel signal corresponding to incident light based on a first power supply voltage and a first ground voltage;
a reference voltage generator generating a reference signal; and
a comparator comparing the pixel signal with the reference signal based on the first power supply voltage and the first ground voltage,
wherein the reference voltage generator includes:
a reference current generator generating a reference current based on the first power supply voltage and the first ground voltage;
a current amount adjuster adjusting the reference current generated by the reference generator based on a second power supply voltage and a second ground voltage; and
a reference voltage generator generating the reference signal corresponding to the reference current, which is adjusted by the current adjuster, based on the first power supply voltage and the first ground voltage,
wherein the second power supply voltage used for operating the current amount adjuster is a separate power supply voltage that is different from the first power supply voltage used for operating the pixel, the comparator, the reference current generator, and the reference voltage generator.
2. The CMOS image sensor of claim 1 , wherein the current amount adjuster unit is linked to the reference current generator and the reference voltage generator by using a diode-connected metal-oxide semiconductor (MOS) and a current flowing therethrough.
3. The CMOS image sensor of claim 1 , wherein the current amount adjuster is linked to the reference voltage generator by using a diode-connected metal-oxide semiconductor (MOS) and a current flowing therethrough.