Adaptive operational transconductance amplifier load compensation
AssigneeMicron Technology, Inc.
InventorRobert Johansson
Life of this patent
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Abstract
A buffer varies the size of its output stage in response to a varying capacitive load. The capacitive load may vary in a predictable or a random manner. The buffer includes an operational amplifier having an output stage of multiple transistors, selectively connected in parallel. During operation, data regarding the size of the capacitive load is obtained and used to determine the size of the output stage. In general, as the capacitive load increases, the number of transistors connected in parallel at the output stage also increases.
Claims8
In an image sensor, a buffer for setting a reference voltage on a common plate of a plurality of capacitors, the buffer comprising
- input and output nodes,
- a reference voltage provided at the input node and buffered to the output node, and
- a plurality of transistors selectively connected in parallel at the output node,
- wherein the common plate of the plurality of capacitors is connected to the output node, and
- a first number of transistors of the plurality of transistors selectively connected in parallel increases as a second number of capacitors of the plurality of capacitors connected to the output node increases.
A method of maintaining a reference voltage at a common node of a plurality of capacitors, the method comprising the steps of:
- selectively connecting the plurality of capacitors in parallel for varying a capacitive load between input and output signals;
- buffering the reference voltage between input and output nodes of a buffer, the buffer including a plurality of output transistors;
- connecting the output node of the buffer to the common node of the plurality of capacitors;
- and
- selectively connecting the plurality of output transistors to the common node based on the plurality of capacitors selectively connected between the input and output signals;
- wherein a number of the output transistors connected to the common node increases when a number of capacitors connected between the input and output signals increases.
Dependencies are inferred from the claim text.