Semiconductor device and method of forming same for acoustic sensing of close proximity objects

摘要

In embodiments a circuit provides a circuit for use in detecting close proximity objects in an acoustic distance sensing system. The circuit produces a close proximity zone flag when the time after transmitting an acoustic distance sensing pulse corresponds to the defined close proximity range. The circuit can also include a time of flight counter for determining the time of flight of a received echo. The circuit can further produce a close proximity time if flight valid flag indicating that echoes are being received in close proximity time frame.

主权项

1. A semiconductor device, comprising:
a close proximity zone flag circuit operable to assert a close proximity zone flag while a present period of a received signal from an acoustic transducer is within a preselected range during a proximity window time period; a time of flight circuit operable to produce a time of flight count based on a time period when a stream of present periods of the received signal, after being low pass filtered, overcrosses a preselected threshold value; and a close proximity time of flight valid flag circuit operable to compare the time of flight count to a valid time interval threshold value and assert a close proximity time of flight valid flag when the time of flight count is within the valid distance threshold interval.