A 10.4pJ/b (32, 8) LDPC decoder with time-domain analog and digital mixed-signal processing

Analog computation is potentially more efficient in certain arithmetic operations since a single wire can represent multiple bits of information, while digital systems retain advantages, for example, in logical operations. However, the use of conventional voltage-domain analog computation [1, 2] is limited due to its poor scalability, design complexity, and the overhead of interface circuits (i.e. ADC/DAC) to a surrounding digital system. Therefore, an alternate technique is required for exploiting the efficiency of analog computation. In this paper, we propose time-domain analog and digital mixed (TDMixed) signal processing, wherein time instead of voltage is utilized as the analog signal. To verify the validity of the TDMixed signal processing, we implement an (32, 8) low-density parity-check (LDPC) decoder in 65nm CMOS. The decoder achieves power and area efficiencies of 10.4pJ/b and 6.1Gb/s/mm², respectively.