Instrumentation amplifier with rail-to-rail input range
AssigneeSemtech Corporation
InventorsOlivier Nys, Francois Krummenacher
Life of this patent
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Abstract
A system and method for adjusting a common mode output voltage in an instrumentation amplifier is provided. In one aspect, the common mode output voltage is increased or decreased with respect to the common mode input voltage to enable high amplification of the signal input to the instrumentation amplifier. Moreover, the common mode output voltage can be driven to (or approximately to) a target voltage value such as, but not limited to, half the supply, even if the common mode input voltage is close to supply or ground rail voltage. Thus, a high amplification of the differential input voltage can be obtained and utilized for various applications requiring rail to rail input.
Claims20
A method comprising:
- measuring output voltage signals from an instrumentation amplifier;
- comparing the output voltage signals with a predefined voltage range;
- based on the comparing, determining that at least one of the output voltage signals does not lie within the predefined voltage range;
- and
- in response to the determining, generating a control signal for adjusting a common mode output voltage to prevent saturation of the instrumentation amplifier, wherein the generating comprises generating a controlled current signal that is passed through an input resistor of the instrumentation amplifier.
A system, comprising:
- an instrumentation amplifier that amplifies a differential input voltage signal to generate output voltage signals;
- a control circuit that compares the output voltage signals with a defined voltage range and in response to a determination that at least one of the output voltage signals does not lie within the defined voltage range, generates a control signal that is employable to modify a common mode output voltage of the instrumentation amplifier to avoid saturation of the instrumentation amplifier;
- and
- a controlled current source that generates a common mode current that flows through input resistors of the instrumentation amplifier, wherein the controlled current source is controlled by the control signal.
A system, comprising:
- a first circuit configured to determine a common mode output voltage of an instrumentation amplifier based on the output voltage signals of the instrumentation amplifier;
- and
- a second circuit configured to generate a control signal that reduces a difference between the common mode output voltage and a target voltage, wherein the second circuit compares the output voltage signals with a defined voltage range and generates the control signal in response to a determination that at least one of the output voltage signals does not lie within the defined voltage range, and wherein the control signal adjusts a current signal that flows through input resistors of the instrumentation amplifier.
Dependencies are inferred from the claim text.