Patent ID: 7800253

Claim:
A system comprising: an interconnect to carry direct current (DC), the interconnect having a first conductor and a second conductor; an electronic device connectable to the interconnect to receive DC and having a communication circuit to transmit signals over the interconnect; and, a power supply connectable to the interconnect to provide the DC to the electronic device and having a decoder circuit to decode the signals received over the interconnect from the electronic device, where the decoder circuit is part of the power supply, wherein the decoder circuit is one of: a first decoder circuit comprising: a first operational amplifier having a positive input, a negative input, and an output, the positive input connected to the second conductor; a first capacitor and a first resistor connected in series between the first conductor and the negative input of the first operational amplifier; a second capacitor and a second resistor connected in parallel between the negative input and the output of the first operational amplifier; a second decoder circuit comprising: a first inverter; a third capacitor connected in series between the first conductor and the first inverter; a third decoder circuit comprising: a second operational amplifier having a positive input, a negative input, and an output, the output connected to the second conductor; a diode connected between the output of the second operational amplifier and the negative input of the second operational amplifier; a third resistor connected between the second conductor and the negative input of the second operational amplifier; a fourth resistor connected between the first conductor and the second conductor; a fourth capacitor connected between the first conductor and the positive input of the second operational amplifier; a second inverter connected to the second operational amplifier.