Demodulation of on-off-key modulated signals in signal isolator systems

An on-off key (“OOK”) receiver system, comprising:

• a voltage divider connected across differential inputs to the receiver system,
• a pair of current routers, each coupled to a common current source, a first current router having inputs coupled to the differential inputs to the receiver system, and a second current router having at least one input coupled to an intermediate node of the voltage divider, wherein transistors of the second current router are larger than transistors of the first current router;
• a comparator having inputs coupled to the current routers and a node for comparison of currents from each of the current routers;
• and
• an output circuit having an input coupled to the node and an output for a binary output signal.

A method of generating a digital voltage signal representing a differential on-off keyed input signal, comprising:

• generating a first current signal representing activity of a differential OOK signal received by an isolator device,
• generating a second current signal representing a common mode level of the differential OOK signal,
• comparing the first and second current signals, and
• generating a binary voltage signal from the current comparison.