A field programmable device or software-defined hardware can change its functions by using software codes to alter the routing path of interconnect signal lines or the electrical properties of fundamental building elements. The field programmable device includes I/O interface blocks and signal processing blocks comprising analog signal processing units, digital signal processing units, memory units, clock units, and other supporting functional units which are electrically connected by user programmable interconnect signal lines. The analog signal processing functions can be altered by changing the electrical properties of fundamental building elements as well as the programmable signal lines after the device is manufactured.