Patent ID: 6459325
Filing Date: 2002-10-01
Classification: H03K

Abstract:
An output buffer comprising:a first P-channel transistor having a first current electrode coupled to a first power supply voltage terminal, a control electrode for receiving a signal corresponding to the input signal, and a second current electrode for providing a predriver signal; a configurable resistance circuit having a first terminal coupled to the second current electrode of the first P-channel transistor, and a second terminal, the configurable resistance circuit switching in a first predetermined resistance during a beginning of a transition of the predriver signal and switching in a second predetermined resistance during an end of the transition of the predriver signal; a first N-channel transistor having a first current electrode coupled to the second terminal of the configurable resistance circuit, a control electrode for receiving the signal corresponding to the input signal, and a second current electrode coupled to a second power supply voltage terminal; a drive transistor, coupled between a third power supply voltage terminal and an output terminal, the drive transistor having a gate for receiving the pre-driver signal, and in response, the drive transistor for transitioning an output signal at the output terminal; and a threshold detection circuit comprising: a second P-channel transistor having a first current electrode coupled to the first power supply voltage terminal, a control electrode coupled to the first current electrode of the first N-channel transistor, and a second current electrode for providing a control voltage to the configurable resistance circuit; and a second N-channel transistor having a first current electrode coupled to the second current electrode of the second P-channel transistor, a control electrode for receiving a control signal, and a second current electrode coupled to the second power supply voltage terminal; the threshold detection circuit causes the configurable resistance circuit to change from the first predetermined resistance to the second predetermined resistance in response to a voltage of the pre-driver signal crossing a predetermined threshold voltage.