Patent ID: 9716850
Date: 2017-07-25
CPC Classifications: H04N

Claim:
1. A bipolar junction transistor (BJT) pixel circuit, configured to generate voltage signals corresponding to a light source signal, the light source signal including a light-on level and a light-off level, the pixel circuit comprising: a photodiode; a first read switch and a second read switch; a first shutter switch configured to control a first exposure time of the photodiode to correspond to the light-on level according to a first shutter signal; a second shutter switch configured to control a second exposure time of the photodiode to correspond to the light-off level according to a second shutter signal; a first storage capacitor having a first terminal coupled to the photodiode via the first shutter switch and a second terminal coupled to a ground, the first storage capacitor configured to hold a first predetermined voltage before the first exposure time and discharge, via the photodiode, to a first output voltage in the first exposure time; a first source follower having a gate coupled to the first terminal of the first storage capacitor, a source coupled to a readout line via the first read switch, and a drain coupled to a power source; a second storage capacitor having a first terminal coupled to the photodiode via the second shutter switch and a second terminal coupled to the ground, the second storage capacitor configured to hold a second predetermined voltage before the second exposure time and discharge, via the photodiode, to a second output voltage in the second exposure time; and a second source follower having a gate coupled to the first terminal of the second storage capacitor, a source coupled to the readout line via the second read switch, and a drain coupled to the power source.