Measurement circuit with improved accuracy
AssigneeTeradyne, Inc.
InventorDavid G. Leip
Life of this patent
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Abstract
A measurement circuit for measuring input voltages in an automatic test system includes a pedestal source, a differential amplifier, and a feedback amplifier. The differential amplifier measures a “residue,” i.e., a difference between an input signal and a pedestal signal from the pedestal source, which is programmed to equal an expected input voltage. The feedback amplifier boosts the residue before it is presented to the differential amplifier, and thus allows the differential amplifier to be operated at lower gain than is typically used in conventional topologies. Consequently, the effect of the errors in the differential amplifier are reduced.
Claims16
A measurement circuit comprising:
- a differential amplifier having a first input and a second input;
- a feedback amplifier having a first input for receiving an input signal to be measured, a second input for receiving a feedback signal, and an output coupled to the second input of the differential amplifier;
- and
- an attenuator coupled between the first and second inputs of the differential amplifier and providing the feedback signal for the feedback amplifier.
An automatic test system for testing electronic devices, comprising:
- a computer for executing a test program,
- stimulus circuits operable under control of the computer;
- and
- measurement circuits operable under control of the computer, at least one of the measurement circuit comprising:
- a differential amplifier having a first input and a second input;
- a feedback amplifier having a first input for receiving an input signal to be measured, a second input for receiving a feedback signal, and an output coupled to the second input of the differential amplifier;
- and
- an attenuator having first and second nodes coupled respectively to the first and second inputs of the differential amplifier, and a third node for providing the feedback signal for the feedback amplifier.
Dependencies are inferred from the claim text.