Patent ID: 11968468
Assignee: OMNIVISION TECHNOLOGIES, INC.
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H | IPC H

Claim 21:
22. An imaging system, comprising:
an array of pixels to receive image light and generate an image charge voltage signal in response; and
readout circuitry coupled to receive the image charge voltage signal from the array of pixels and provide a digital representation of the image charge voltage signal in response, the readout circuitry including a comparator to receive the image charge voltage signal, compare the image charge voltage signals to a ramp signal from a ramp generator, and provide the digital representation of the image charge voltage signal in response, wherein the comparator is coupled to receive the ramp signal through a ramp buffer circuit, wherein the ramp buffer circuit comprises:
a ramp buffer input device having an input coupled to receive the ramp signal;
a current monitor circuit coupled to a power line and the ramp buffer input device, wherein the current monitor circuit is configured to generate a current monitor signal in response to an input current conducted through the ramp buffer input device;
a corner bias circuit coupled to the current monitor circuit, wherein the corner bias circuit is configured to generate an assist bias voltage in response to the current monitor signal received from the current monitor circuit;
a bias current source coupled to an output of the ramp buffer input device, wherein the ramp buffer input device and the bias current source are coupled between a power line and ground;
an assist current source coupled to the corner bias circuit and coupled between the output of the ramp buffer input device and ground, wherein the assist current source is configured to conduct an assist current from the output of the ramp buffer input device to ground in response to the assist bias voltage received from the corner bias circuit.