A 15-Gb/s PAM-3 Transceiver With Hybrid Equalization and Time-Domain Decoder for High-Bandwidth-Memory Interfaces

This study presents a 15-Gb/s three-level pulse amplitude modulation (PAM-3) transceiver (TRX) with a hybrid equalizer and a time-domain decoder using a low supply voltage for high-bandwidth-memory (HBM) interfaces in a 28-nm CMOS technology. To achieve low power consumption in next-generation HBM interfaces, the transmitter employs a hybrid equalizer composed of integrated pulsewidth modulation, a voltage mode feed-forward equalizer, and a delay line controller (DLC). The proposed hybrid equalizer technique reduces input/output capacitance, minimizes bandwidth degradation, and provides effective inter-symbol interference equalization and significant power reduction. The receiver utilizes a time-domain decoder, which halves the number of comparators and reference voltages compared to conventional decoder methods, minimizing hardware cost and design complexity. Additionally, using a low supply voltage in the decoder results in a slower rising slope of the comparator’s output, increasing the decodable range and enhancing power efficiency. Consequently, the proposed TRX achieves a 15-Gb/s data rate with an energy efficiency of 0.253 pJ/bit and occupies 0.0135 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>.