Method and apparatus for a current control

摘要

A current controller includes impedance elements coupled to form at least one impedance ladder circuit which exhibits a fixed impedance at an input and current divider steps each differing in a current magnitude by a multiple of three with respect to the current magnitude in an adjacent less significant step. Single pole triple throw (SPTT) switchably couple an associated step in the impedance ladder circuit to one of three outputs. Three discrete current sources or sinks are each coupled to a corresponding one of the outputs of each of the SPTT switches. The digital driver is coupled to each control input of each SPTT switch to additively deliver selected ones of the stepped currents from each step of the impedance ladder circuit to a corresponding selected one of the current sources or sinks.

主权项

1. A current controller comprising:
discrete impedance elements coupled to one another to form at least one impedance ladder circuit configured to exhibit a fixed impedance at an input and current divider steps each differing in a current magnitude by a multiple of three with respect to the current magnitude in an adjacent less significant step; single pole triple throw (SPTT) switches each including a control input, a current input and three outputs, and each current input coupled to an associated one of the discrete impedance elements associated with each step of the impedance ladder circuit to switchably couple the associated step to a selected one of the three outputs; three discrete current sources or sinks each coupled to a corresponding one of the outputs of each of the SPTT switches; and a digital driver coupled to each control input of each SPTT switch to additively deliver selected ones of the stepped currents from each step of the impedance ladder circuit formed by the discrete input elements to a corresponding selected one of the current sources or sinks.