Area Efficient Approximate 4-2 Compressor and Probability-Based Error Adjustment for Approximate Multiplier

Many multipliers based on approximate compressors have been developed for error-tolerant applications such as image processing to reduce power, but the combination of them has not been fully studied. This brief proposes a novel 4 gate 4-2 approximate compressor which is complementary with other compressors from earlier work and constructs a hybrid multiplier based on the compressors, a constant approximation, and error correction AND gate. According to the simulation results, the proposed hybrid approximate multiplier has excellent accuracy and electrical performance tradeoff and reduces the power-delay-area product (PDAP) by 66% with an MRED of 2.5% when compared to the exact multiplier.