Patent ID: 7804287

Claim:
In an industrial controller comprising a power supply providing a supply voltage and at least one input/output module, wherein the input/output module has at least one current-loop circuit and a logic circuit, which, at least in part, supplies a command signal to each current-loop circuit, the command signal indicating a desired current level for a load connected to the current-loop circuit, the current loop-circuit comprising: at least one load terminal connectable to a load; a control input receiving the command signal from the industrial controller; a current sensor providing a measured current value received by the load through the load terminals; a switching circuit having at least one solid state switch, the switching circuit receiving an error output and a supply voltage and based on the error output periodically connecting the supply voltage to the load terminal to control the current to the load according to the command signal; a low pass filter having multiple stages, wherein: each stage of the filter is connected in series and includes at least one reactive component, the low pass filter generates an anticipating signal prior to at least one of the multiple stages of the filter, at least one of the multiple stages of the low pass filter includes an inductor, and the anticipating signal is generated after the stage including the inductor; a feedback circuit receiving the command signal, the current value, and the anticipating signal to provide the error output; wherein all solid state switches of the switching circuit operate exclusively in a switching mode, being driven to either fully on or fully off states; and wherein current from the switching circuit connects to the load terminal without passing through any additional solid state switching elements not operated in a switching mode.