A 0.385-pJ/bit 10-Gb/s TIA-Terminated Di-Code Transceiver with Edge-Delayed Equalization, ECC, and Mismatch Calibration for HBM Interfaces

The bandwidth of parallel DRAM I/O has increased to meet big-data requirements. High bandwidth memory (HBM) interfaces use up to 1024 pins, and with an increased clock frequency, their power consumption has also increased [1]. Figure 28.5.1 shows four HBM interface approaches. Conventional HBM interfaces use a termination-less structure at the receiver to reduce power consumption. For higher data rates receiver-side termination can be used to improve signal integrity. However, this causes a large static current for long consecutive identical digits (CID). Di-code signaling can be used in HBM interfaces to reduce this static current. Nevertheless, there are still design constraints for conventional di-code interfaces, such as equalization, offset voltage, and series capacitor implementation constraints [2]. The series capacitor, specifically, causes frequency dependence and parasitic capacitance, which degrades its frequency range. In this paper, a capacitor-less and high-efficiency di-code transceiver using trans-impedance-amplifier (TIA) termination is implemented, as shown in Fig. 28.5.1. An adjustable inverter-based TIA is adopted for DC balancing the di-code signaling. A common-mode voltage calibration technique is proposed to minimize the static current during middle-level transmission. Several equalizing techniques for the di-code signaling are proposed to increase the sampling margin at the receiver and to maintain the common-mode voltage of di-code outputs. Also, an error correction circuit (ECC), based on di-code signaling, is implemented to reduce bit errors.