Image sensor array with external charge detection circuitry

摘要

An image sensor may include an array of pixels that do not include any source follower, reset, or addressing transistors, which helps to increase pixel well capacity, reduces or eliminates random telegraph signal (RTS) noise, and reduces undesirable dark current. Charge to voltage conversion may be performed by charge detection circuitry that is external to the array of pixels. The charge detection circuitry may include amplifier circuitry such as an operational amplifier and may be located at the periphery of the array of pixels or on a different semiconductor substrate. By locating the charge detection circuitry outside of the array of pixels, additional flexibility may be provided for the charge detection circuitry. The charge detection circuitry may be provided with switchable gain or with non-linear charge to voltage conversion capability.

主权项

1. An image sensor, comprising:
an array of pixels that do not include any source follower transistors, wherein at least a portion of the array of pixels is coupled to a signal bus; and charge detection circuitry that is external to the array of pixels and coupled to the signal bus, wherein the charge detection circuitry comprises:
pre-charge circuitry that includes a switch and a capacitor coupled to the signal bus, wherein the switch is operable in a first state in which the capacitor has a first capacitance value and a second state in which the capacitor has a second capacitance value, wherein the pre-charge circuitry increases a voltage swing at an output of the charge detection circuitry by changing the switch from the first state to the second state to provide the second capacitance to the signal bus.