System and method for improving speed and power in a switched-capacitor amplifier
AssigneeAnalog Devices, Inc.
InventorsWilliam T. Boles, Michael R. Elliott
Life of this patent
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Abstract
A multiplying analog-to-digital converter (“MDAC”) that reduces the power consumption of the MDAC by at least 2.3 times by improving the feedback factor. The amplifier may include a feed forward approach in which the input capacitor (also referred to as “sampling capacitor”) is buffered by a common gate amplifier to improve bandwidth by removing input and parasitic capacitance terms from the global feedback loss. THe amplifier may also use an alternate form of local compensation, for example, cascode compensation. The amplifier may also further include an alternate way to reduce parasitic capacitance with a buffer.
Claims18
A method for improving the efficiency of a switched-capacitor amplifier having a sampling capacitor and a feedback capacitor, the method comprising:
- buffering the sampling capacitor from the feedback capacitor such that a gain of the amplifier is maintained and a feedback factor of the amplifier is increased by removing a capacitance of the sampling capacitor from the feedback factor.
A multiplying digital-to-analog converter comprising:
- a first stage including:
- an input capacitor coupled to an input of the multiplying digital-to-analog converter;
- and
- a common-gate amplifier coupled to the input capacitor and a first current source;
- and
- a second stage coupled to an output of the first stage, the second stage including:
- an amplifier having an input coupled to an intermediate node of the common-gate amplifier;
- and
- a feedback capacitor coupled to the input of the amplifier and an output of the amplifier.
A multiplying digital-to-analog converter comprising:
- a first stage including:
- an input capacitor coupled to an input of the multiplying digital-to-analog converter;
- a common-gate amplifier coupled to the NMOS;
- and
- an NMOS having a drain coupled to the common-gate amplifier, and a source coupled to a first current source;
- and
- a second stage coupled to an output of the first stage, the second stage including:
- an amplifier having an input coupled to an intermediate node of the common-gate amplifier;
- and
- a feedback capacitor having an input coupled to the common-gate amplifier and the drain of the NMOS, and an output coupled to an output of the amplifier.
Dependencies are inferred from the claim text.