Sampling circuits
AssigneeMediatek Inc.
InventorPao-Cheng Chiu
Life of this patent
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Abstract
A sampling circuit includes an amplifier, a sampling capacitor, a feedback capacitor, and a voltage source. The sampling capacitor and the feedback capacitor are coupled to the same input terminal of the amplifier, such that the offset of the amplifier and low-frequency noise can be cancelled. The voltage source can shift the voltage level of an output signal of the sampling circuit by the difference between the input and output common mode voltages of the amplifier, so that an amplifier having different input common mode voltage and output common mode voltage can be adopted, and the capacitance of the sampling capacitor and that of the feedback capacitor can be different, resulting in a non-unit gain.
Claims16
A sampling circuit operating in a sampling phase and a holding phase, comprising:
- an amplifier having a first input terminal and an output terminal for outputting an output signal;
- a first capacitor, coupled to the first input terminal, for sampling an input signal during the sampling phase;
- a second capacitor, having a first terminal coupled to the first input terminal and a second terminal coupled to the output terminal during the holding phase and decoupled from the output terminal during the sampling phase, for sampling a reference signal during the sampling phase and receiving charges from the first capacitor during the holding phase;
- and
- a voltage source, coupled between the first input terminal and the output terminal, for providing a predetermined voltage level during the sampling phase to eliminate difference between an input common mode voltage and an output common mode voltage of the amplifier;
- wherein the input common mode voltage of the amplifier is different from the reference signal;
- and
- wherein the output common mode voltage of the amplifier is different from the reference signal.
A sampling circuit operating in a first phase and a second phase, comprising:
- an amplifier having a first input terminal and an output terminal for outputting an output signal;
- a first capacitor, coupled to the first input terminal, for sampling an input signal during the first phase and the second phase;
- a second capacitor, having a first terminal coupled to the first input terminal and a second terminal coupled to the output terminal during the second phase and decoupled from the output terminal during the first phase, for sampling a reference signal during the first phase and receiving charges from the first capacitor during the second phase;
- and
- a voltage source, coupled between the first input terminal and the output terminal, for providing a predetermined voltage level during the first phase to eliminate difference between an input common mode voltage and an output common mode voltage of the amplifier.
Dependencies are inferred from the claim text.