Pulse density mapping method and circuit for delta sigma modulators

A method for mapping the serial 0 and 1 pulses received at a known clock rate from a delta sigma modulator All 0's are generated at the output when no 11 pairs are present in the input signal during the sampled clock periods. A 1 is generated at the output responsive to the input signal and the input signal delayed by one clock period both being 1's when no 00 pairs are present in the input signal during the sampled clock periods. A 1 is generated at the output for each 11 pair not balanced by a 00 pair when 11 and 00 pairs are serially alternating in the input signal during the sampled clock periods. According to this mapping method, the pulse density of 1's in the output signal increases only responsive to an increase in the net number of 11 pairs in the input signal during the sampled clock periods. A circuit for implementing this pulse mapping method is also described.