Patent ID: 6664805
Filing Date: 2003-12-16
Classification: H03K

Abstract:
A method for reducing the slew rate of a signal on a transmission line driven by an output switching device, said output switching device characterized by a turn-on threshold voltage and comprising a control input responsive to a predrive signal for placing said output switching device in one of an OFF state, a linear state, or an ON state, wherein: said output switching device is in said OFF state not driving said transmission line when said predrive signal is at a voltage level between said turn-on threshold voltage and an OFF voltage level; said output switching device is in a linear state driving said transmission line to a voltage level proportional to said predrive signal when said predrive signal is at a voltage level between said turn-on threshold voltage and a saturation voltage level; and said output switching device is in said ON state driving said transmission line to predetermined constant voltage level when said predrive signal is at a voltage level between said saturation voltage level and said ON voltage level, said method comprising:connecting a predetermined first capacitance in a switched capacitance sequence comprising a plurality of capacitance steps to the control input of said output switching device; determining whether a next sequential capacitance step exists in said switched capacitance sequence; if a next sequential capacitance step exists in said switched capacitance sequence, connecting a predetermined next capacitance in said switched capacitance sequence to said control input of said output switching device; repeating said determining step through said repeating step until no next sequential capacitance step exists in said switched capacitance sequence; monitoring a voltage level on at least one of said control input of said output switching device and said transmission line; and when said monitored voltage level reaches a predetermined reference voltage, connecting said control input of said output switching device to said ON voltage source.