Auto-nulled bandgap reference system and strobed bandgap reference circuit
AssigneeAnalog Devices, Inc.
InventorsMichael A. Ashburn, Jr., Stephen W. Harston
Life of this patent
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Abstract
An auto-nulled bandgap reference system employing a substrate bandgap reference circuit with primary and auxiliary amplifiers and a switching circuit which in a first mode develops a voltage to null the offset and noise errors of the auxiliary amplifier and then in the second mode uses the nulled auxiliary amplifier to develop a voltage to null the offset and noise errors of the primary amplifier; and a strobe circuit including an output storage device and a strobe control circuit for periodically powering up a bandgap reference circuit to charge the output storage device and powering down the bandgap reference circuit to conserve power.
Claims36
An auto-nulled bandgap reference system comprising:
- a substrate bandgap core having a differential output;
- a primary amplifier for receiving at its input said differential output and a feedback circuit responsive to said primary amplifier to drive to zero said differential output at its input;
- said primary amplifier having inherent offset and noise errors;
- a first storage device connected to a nulling input of said primary amplifier;
- an auxiliary amplifier having inherent offset and noise errors;
- a second storage device connected to a nulling input of said auxiliary amplifier;
- and
- a switching circuit for selectively, in a first mode, shorting the inputs of said auxiliary amplifier and connecting its output to said second storage device to develop a compensation voltage for nulling the noise and offset error of said auxiliary amplifier and in a second mode connecting the input of said nulled auxiliary amplifier in parallel with the input to said primary amplifier and connecting the output of said nulled auxiliary amplifier to said first storage device to develop a compensation voltage for nulling the noise and offset error of said primary amplifier.
An auto-nulled bandgap reference system comprising:
- a substrate bandgap reference circuit including a primary amplifier having inherent offset and noise error;
- an auxiliary amplifier circuit having inherent offset and noise error;
- and
- a switching circuit for, in a first mode, developing a voltage to null the offset and noise errors of said auxiliary amplifier and in a second mode connecting together in parallel the inputs of said primary and auxiliary amplifiers for developing with said nulled auxiliary amplifier a voltage to null the offset and noise errors of said primary amplifier.
Dependencies are inferred from the claim text.