Low power amplifier structures and calibrations for the low power amplifier structures
AssigneeAnalog Devices, Inc.
InventorAhmed Mohamed Abdelatty Ali
Life of this patent
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Abstract
Amplifiers can be found in pipelined ADCs and pipelined-SAR ADCs as inter-stage amplifiers. The amplifiers can in some cases implement and provide gains in high speed track and hold circuits. The amplifier structures can be open-loop amplifiers, and the amplifier structures can be used in MDACs and samplers of high speed ADCs. The amplifiers can be employed without resetting, and with incomplete settling, to maximize their speed and minimize their power consumption. The amplifiers can be calibrated to improve performance.
Claims20
An open-loop amplifier, comprising:
- a differential pair of input transistors to receive differential inputs at respective gates of the differential pair of input transistors;
- a first current source to provide current for the open-loop amplifier;
- an active load at differential output nodes of the open-loop amplifier;
- load resistance at the differential output nodes of the open-loop amplifier, wherein the load resistance comprises a load transistor controlled to operate in a linear region, a drain and a source of the load transistor are coupled to differential output nodes of the open-loop amplifier respectively;
- and
- an analog tracking circuit to generate a gate voltage to drive the load transistor, wherein the gate voltage tracks a sum of a gate-to-source voltage of the load transistor and an ideal common mode voltage of the open-loop amplifier.
An open-loop amplifier, comprising:
- a first pair of input transistors to receive differential inputs at respective gates of the first pair of input transistors;
- a second pair of input transistors, which are complementary to the first pair of input transistors, to receive differential inputs at respective gates of the second pair of input transistors;
- a first current source at terminals of the first pair of input transistors to provide current for the open-loop amplifier;
- and
- load resistance at differential output nodes of the open-loop amplifier, wherein the load resistance comprises a first load transistor of a first type across the differential output nodes of the open-loop amplifier, and a second load transistor of a second type different from the first type in parallel with the first load transistor, wherein the first load transistor and the second load transistor are controlled to operate in a linear region.
A method to improve performance of an open-loop amplifier, comprising:
- tracking one or more factors affecting an ideal gate-to-source voltage for operating a load transistor across differential output nodes of the open-loop amplifier;
- wherein the one or more factors comprises one or more of the following:
- process, temperature, voltage, a voltage across transistors in the open-loop amplifier, a transconductance or resistance of transistors in the open-loop amplifier, a gain setting in the open-loop amplifier, a bias current setting in the open-loop amplifier, and an error obtained from calibration of the open-loop amplifier;
- and
- generating a gate voltage to drive load transistor and operate the load transistor in a linear region, based on the one or more factors and an ideal common-mode voltage of the open-loop amplifier, wherein the gate voltage tracks a sum of a gate-to-source voltage of the load transistor and an ideal common mode voltage.
Dependencies are inferred from the claim text.