INTEGRATED CMOS CIRCUIT WITH DIFFERENTIAL OPEN DRAIN OUTPUT DRIVER
An integrated CMOS circuit with a differential open drain output driver comprises a plurality of differential output stages each having differential inputs and differential outputs, the differential outputs of the differential output stages being interconnected to provide a pair of differential open drain driver outputs, and the differential inputs of the differential output stages being driven by a pair of inverter chains each of which has an input receiving one of a pair of differential input signals and cascaded inverter stages each with an output connected to an input of one of the differential output stages.
1 . An integrated CMOS circuit with a differential open drain output driver, comprising a plurality of differential output stages and a pair of inverter chains; each differential output stage having differential inputs and differential output, with corresponding ones of the differential outputs of the plurality of differential output stages being interconnected to provide a pair of differential open drain driver outputs, and with corresponding ones of the differential inputs of the plurality of differential output stages being driven by a respective one of the inverter chains; each inverter chain having an input receiving one of a pair of differential input signals and comprising a plurality of cascaded inverter stages, each with an output connected to a respective input of one of the differential output stages.
2 . The circuit of claim 1 , wherein output nodes of successive inverter stages in each inverter chain are connected to differential inputs of a same polarity, opposite to the polarity of differential input signals applied to an input of the first inverter in each inverter chain.
3 . The circuit of claim 2 , wherein each differential output stage includes a source circuit with a current mirror that mirrors a reference current.
4 . The circuit of claim 3 , wherein the differential output stages are staggered in terms of current supplied by the associated current mirrors.
5 . The circuit of claim 4 , wherein the current mirror of the output stage driven by a last one of the inverter stages of each inverter chain supplies a substantially higher current than the current mirror of the output stage driven by a first one of the inverter stages in each inverter chain.
6 . The circuit of claim 1 , wherein each differential output stage includes a source circuit with a current mirror that mirrors a reference current.
7 . The circuit of claim 6 , wherein the differential output stages are staggered in terms of current supplied by the associated current mirrors.
8 . The circuit of claim 7 , wherein the current mirror of the output stage driven by a last one of the inverter stages of each inverter chain supplies a substantially higher current than the current mirror of the output stage driven by a first one of the inverter stages in each inverter chain.
9 . The circuit of claim 6 , wherein the current mirror of the output stage driven by a last one of the inverter stages of each inverter chain supplies a substantially higher current than the current mirror of the output stage driven by a first one of the inverter stages in each inverter chain.