For example, consider two 3-bit XOR based LFSRs with different tap selections ( Fig 2).Ģ. The sequence of values generated by an LFSR is determined by its feedback function (XOR versus XNOR) and tap selection. The data input to the LFSR is generated by XOR-ing or XNOR-ing the tap bits the remaining bits function as a standard shift register. All of the register elements share a common clock input, which is omitted from the symbol for reasons of clarity. The taps in this example are at bit 0 and bit 2, and can be referenced as.
