Variable gain instrumentation amplifier
AssigneeQUALCOMM Incorporated
InventorPaul L Bugyik
Life of this patent
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Abstract
Techniques for providing an instrumentation amplifier having a plurality of selectable gain settings. In an exemplary embodiment, a gain adjustment block for accepting a differential input voltage is coupled to a differential-to-single-ended conversion block for generating a single-ended output voltage. The gain adjustment block may have a plurality of gain settings selectable by one or more switches. The instrumentation amplifier advantageously offers precise gain control without the need for external calibration, while being robust and simple to design.
Claims9
An on-chip instrumentation amplifier for converting a differential voltage signal to a single-ended output voltage signal during testing of on-chip components, comprising:
- a plurality of switchable feedback paths associated with a discrete plurality of gain settings, each gain setting being defined by having (i) a negative input voltage of the differential voltage signal received at a positive input terminal of a first operational amplifier, (ii) a positive input voltage of the differential voltage signal received at a positive input terminal of a second operational amplifier, (iii) a negative input terminal of the first operational amplifier coupled via a first switch S1 to a programmably selected one of a first node of each switchable feedback path, and (iv) a negative input terminal of the second operational amplifier coupled via a switch S2 to a programmably selected one of a second node of each switchable feedback path,
- wherein each switchable feedback path has a predefined corresponding feedback resistance Rn.1 and a corresponding shunt resistance Rn.2, where the values Rn.2 for each switchable feedback path is different than that of the other switchable feedback paths.
In an on-chip instrumentation amplifier that converts a differential voltage signal to a single-ended output voltage signal during testing of on-chip components, comprising a plurality of switchable feedback paths, each gain setting being defined by having (i) a negative input voltage of the differential voltage signal received at a positive input terminal of a first operational amplifier, (ii) a positive input voltage of the differential voltage signal received at a positive input terminal of a second operational amplifier, (iii) a negative input terminal of the first operational amplifier coupled via a first switch S1 to a programmably selected one of a first node of each switchable feedback path, and (iv) a negative input terminal of the second operational amplifier coupled via a switch S2 to a programmably selected one of a second node of each switchable feedback path, wherein each switchable feedback path has a predefined corresponding feedback resistance Rn.1 and a corresponding shunt resistance Rn.2, where the values Rn.2 for each switchable feedback path is different than that of the other switchable feedback paths, a method comprising:
- identifying a desired gain setting value;
- and
- selectably programming S1 and S2 to select one of the plurality of switchable feedback paths providing the desired gain setting value.
Dependencies are inferred from the claim text.