US 12,281,937 B1
Image sensor including peak hold circuit
Yoshiyuki Matsunaga, Kyoto (JP); Keiji Mabuchi, Cupertino, CA (US); and Lindsay Grant, Campbell, CA (US)
Assigned to OmniVision Technologies, Inc., Santa Clara, CA (US)
Filed by OmniVision Technologies, Inc., Santa Clara, CA (US)
Filed on Dec. 15, 2023, as Appl. No. 18/542,439.
Int. Cl. G01J 1/44 (2006.01)
CPC G01J 1/44 (2013.01) [G01J 2001/446 (2013.01)] 7 Claims
OG exemplary drawing
 
1. A pixel circuit, comprising:
a photodiode configured to operate in a photovoltaic mode and to accumulate charges corresponding to an incident light amount;
a reset transistor configured to reset the accumulated charges of the photodiode; and
a peak hold circuit configured to hold an output corresponding to the accumulated charges of the photodiode, the peak hold circuit including a peak hold transistor connected to an output end of the photodiode, a switching transistor configured to turn on/off an output of the peak hold transistor, and a holding capacitor configured to hold an output of the switching transistor, wherein
the peak hold transistor operates in a state where no carrier charge or only one carrier charge is present on a channel of the peak hold transistor, and wherein
the peak hold transistor operates under a condition that a drain current is less than or equal to kT*μe/L2 while no charge or only a single charge is present on the channel of the peak hold transistor, where k is a Boltzmann constant, T is an absolute temperature, μe is mobility of an electron, and L is a gate length of the peak hold transistor.