Abstract: A low noise output buffer to simultaneously reduce switching noise and output signal ringing for output ringing and maintain DC current. A temporary and a steady-state output buffers are supplied by a buffer voltage source and an internal circuit voltage source, respectively. Each driver has a pull-up and a pull-down transistors. While switching the output buffer from a high voltage level to a low voltage level or from a low voltage level to a high voltage level, a predriver and a single steady-state circuit are designed to respectively generate a large simultaneous switching noise at the buffer voltage source and a small simultaneous switching noise at the internal circuit voltage source. A Schmitt trigger circuit is also used to turn off the temporary driver, so as to reduce the output signal ringing while the steady-state driver maintains a supply of DC current.

Abstract: A low noise output buffer to simultaneously reduce switching noise and output signal ringing for output ringing and maintain DC current. A temporary and a steady-state output buffers are supplied by a buffer voltage source and an internal circuit voltage source, respectively. Each driver has a pull-up and a pull-down transistors. While switching the output buffer from a high voltage level to a low voltage level or from a low voltage level to a high voltage level, a predriver and a single steady-state circuit are designed to respectively generate a large simultaneous switching noise at the buffer voltage source and a small simultaneous switching noise at the internal circuit voltage source. A Schmitt trigger circuit is also used to turn off the temporary driver, so as to reduce the output signal ringing while the steady-state driver maintains a supply of DC current.