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US 8,576,002 B2Granted
ADC preamplifier and the multistage auto-zero technique
AssigneeAnalog Devices, Inc.
InventorSanjay Rajasekhar
Life of this patent
Estimating the term…
Abstract
Embodiments of the present invention provide a sample and hold amplifier that provides a preamplifier with a multi-stage zeroing architecture. The multi-stage architecture reduces effects of parasitic capacitance exponentially over prior attempts, which yields increased accuracy.
Claims16
A pre-amplifier system, having an input terminal for an input signal, comprising:
- an amplifier with a pair of input terminals and an output terminal;
- and
- an auto-zeroing stage comprising:
- a capacitor having a first terminal coupled to an input terminal of the amplifier,
- a first pair of switches to connect the capacitor between the amplifier output and the input signal terminal in a first phase of operation, and
- a third switch to connect a second terminal of the capacitor to the input signal terminal in a second phase of operation.
3 more elements
A method of capturing an input voltage, comprising:
- in a first phase,
- applying the input voltage to an amplifier to generate an output voltage,
- developing a voltage across a capacitor representing a difference between the input voltage and the output voltage;
- and
- in a second phase,
- reversing an orientation of the capacitor voltage, and
- applying a combination of the input voltage and the reversed capacitor voltage to the amplifier.
4 more elements
An amplifier system, comprising:
- an amplifier with a pair of input terminals and an output terminal;
- and
- a plurality of auto-zeroing stages, each stage comprising:
- a capacitor, and
- a plurality of switches,
- wherein each capacitor is switchably coupled to the output terminal and switchably coupled to an input voltage terminal.
3 more elements
An amplifier system, comprising:
- an amplifier with an output terminal;
- and
- a plurality of auto-zeroing stages, each stage comprising:
- a capacitor,
- a first pair of switches that, when activated, couple a first capacitor terminal of the capacitor to an input of the respective stage and a second capacitor terminal to the amplifier output terminal, and a
- third switch that, when activated, couples the second capacitor terminal to the input of the stage.
3 more elements
A method of capturing an input voltage, comprising:
- in a first phase,
- applying the input voltage to an amplifier to generate an output voltage,
- developing a voltage across a capacitor of a first stage representing a difference between the input voltage and the output voltage;
- and
- in successive phases,
- reversing orientation of the capacitor voltage of a preceding stage,
- applying a combination of the input voltage and the reversed capacitor voltages of all preceding stages to the amplifier, and
- developing a voltage across a capacitor of a next stage representing a difference between the input voltage and the output voltage.
5 more elements
Dependencies are inferred from the claim text.