Multi-Path Common Mode Feedback for High Speed Multi-Stage Amplifiers
AssigneeTexas Instruments Incorporated
InventorsAmit Kumar Gupta, Vijayakumar Dhanasekaran, Karthikeyan Soundarapandian
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Abstract
The invention includes methods and systems for providing a multi-path common mode feedback loop in an amplifier system. Embodiments include techniques for dividing a common mode feedback current path to provide a slow common mode feedback current path and a fast common mode feedback current path. The slow and fast paths are configured for controlling common mode feedback current within a small bandwidth.
Claims16
A system for common mode feedback in a fully differentiated multi-stage amplifier system, comprising:
- a multi-path common mode feedback loop configured for narrow bandwidth and large bias current.
A multi-path common mode feedback system for a high speed multi-stage amplifier, comprising:
- a slow path further comprising a series RC low pass filter operably coupled to a slow path transistor;
- and
- a fast path further comprising a fast path transistor;
- wherein the slow path and fast path are configured for controlling a common mode feedback current within a small bandwidth.
A method for controlling a common mode feedback loop for a multi-stage amplifier system, comprising the steps of:
- dividing the common mode feedback current path;
- thereby
- providing a slow common mode feedback current;
- and
- providing a fast common mode feedback current path;
- wherein the slow path and fast path are configured for controlling a common mode feedback current within a narrow bandwidth.
A multi-path common mode feedback system comprising:
- a fast path having a fast path transistor, the fast path configured for determining the bandwidth of the common mode feedback loop;
- and
- a slow path having a slow path transistor operably coupled to a low pass filter, the low pass filter having a 3 dB bandwidth of about one-tenth of the fast path bandwidth;
- wherein the slow path and fast path are configured to operate in combination to determine the direct current carrying capacity of the common mode loop, and wherein the bandwidth of the loop is determined by how the current is divided between the fast path and the slow path.
Dependencies are inferred from the claim text.