Current based sensor analog signal processing technique for extracting the feedback signal

In a closed loop system, feedback signals are continuously being fed back and compared with the input signal. The difference between the input signal and the feedback signal is being used by the system so as to reduce the error signal and bring the output of the system to a desired value. By knowing the transfer function and measuring the feedback signal, the corresponding input signal can be obtained. Most sensor systems are implementing feedback for several reasons. A common reason is to minimize the large signal linearity problem. This paper presents a circuit architecture that enables the extraction of the feedback current signal without giving significant influence as it is the case for typical shunt resistor solutions. The whole system is being realized in an integrated circuit 0.35μm CMOS technology using 1.5 V power supply.