Method of and apparatus for detecting open circuit conditions at an input to a signal chain and for detecting channel imbalance in a differential signal chain
AssigneeAnalog Devices Global Unlimited Company
InventorsJonathan Ephraim David Hurwitz, Jesus Bonache, Robert Sythes, Eamonn J. Byrne
Life of this patent
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Abstract
It is often desirable to distinguish between an open circuit condition and a no signal condition. In both cases an input signal may be absent, but only one of these events represents a failure of the equipment. The present disclosure provides a way to use a difference amplifier to check for open circuit events, without requiring additional circuitry at the input of the amplifier.
Claims20
A method of detecting channel imbalance in a circuit that comprises a differential signal processing circuit, the method comprises:
- applying a periodic voltage signal to common mode inputs of the differential signal processing circuit, the common mode inputs being distinct from signal input nodes of the differential signal processing circuit, wherein the periodic voltage signal is defined as a signal that cycles between two values over time;
- and
- monitoring a differential voltage received from outputs of the differential signal processing circuit for changes that are correlated with changes in the periodic voltage signal applied to the common mode inputs.
An apparatus for detecting channel imbalance in a differential signal processing system having a node for controlling a common mode value of a differential output signal, the apparatus comprising:
- common mode inputs of the differential signal processing system that receive a periodic voltage signal, the common mode inputs being distinct from signal input nodes of the differential signal processing system, wherein the periodic voltage signal is defined as a signal that cycles between two values over time;
- and
- a processor coupled to receive outputs of the differential signal processing system for examining a correlation between the received outputs of the differential signal processing system and the periodic voltage signal applied to the common mode inputs to identify channel imbalance.
An apparatus comprising:
- means for applying a periodic voltage signal to common mode inputs of a differential signal processing circuit, the common mode inputs being distinct from signal input nodes of the differential signal processing circuit, wherein the periodic voltage signal is defined as a signal that cycles between two values over time;
- and
- means for monitoring a differential voltage received from outputs of the differential signal processing circuit for changes that are correlated with changes in the periodic voltage signal applied to the common mode inputs.
Dependencies are inferred from the claim text.