Abstract: A frequency coincidence detection circuit for detecting frequency edges for each of a plurality of periodic digital signals. The circuit generates count indicators for each of the periodic digital signals and compares each of the count indicators to a programmable sensitivity input to determine a coincidence window for the corresponding one of each of the periodic digital signals. The circuit determines a signal coincidence of the coincidence windows. In another embodiment, a frequency coincidence detection method is provided. The method detects frequency edges for each of a plurality of periodic digital signals, generates count indicators for each of the periodic digital signals and compares each of the count indicators to a programmable sensitivity input to determine a coincidence window for the corresponding one of each of the periodic digital signals. The method determines a signal coincidence of the coincidence windows.

Abstract: An I/O buffer circuit including: a driver circuit containing a pull-up device in a first floating well and a pull-down device in a second floating well; a first and second biasing circuits to bias the first and second floating wells in response to voltages internal and external to the I/O buffer circuit; and a first and second tracking circuits to bias each of said pull-up and pull-down devices in response to voltages internal and external to the I/O buffer circuit in a shutdown mode.