Design of NRZ/PAM-3/PAM-4 Tri-Mode Single-Ended Transmitter for Next-Generation Memory Interfaces
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This paper presents a single-ended voltage-mode transmitter for next-generation memory interfaces, supporting three signaling modes: non-return-to-zero (NRZ), three-level pulse amplitude modulation (PAM-3), and four-level pulse amplitude modulation (PAM-4). Utilizing the same output driver, the tri-mode transmitter effectively reduces the development cycle and associated costs for intellectual property (IP) development. Firstly, based on the mode selection signal, two mode selectors determine which data are passed to the tri-mode driver, outputting the data in either NRZ, PAM-3, or PAM-4 signaling. Secondly, 2-tap feed-forward equalizers (FFE) are separately applied to the three modes, compensating for signal distortions caused by losses in signal transmission through the channel based on different FFE encodings. A seven-step four-point ZQ calibration with offset cancellation is implemented to improve the level separation mismatch ratio. Designed using 65-nm CMOS technology, the transmitter achieved data rates of 16-Gb/s in NRZ mode, 24-Gb/s in PAM-3 mode, and 32-Gb/s in PAM-4 mode.
Abstract
This paper presents a single-ended voltage-mode transmitter for next-generation memory interfaces, supporting three signaling modes: non-return-to-zero (NRZ), three-level pulse amplitude modulation (PAM-3), and four-level pulse amplitude modulation (PAM-4). Utilizing the same output driver, the tri-mode transmitter effectively reduces the development cycle and associated costs for intellectual property (IP) development. Firstly, based on the mode selection signal, two mode selectors determine which data are passed to the tri-mode driver, outputting the data in either NRZ, PAM-3, or PAM-4 signaling. Secondly, 2-tap feed-forward equalizers (FFE) are separately applied to the three modes, compensating for signal distortions caused by losses in signal transmission through the channel based on different FFE encodings. A seven-step four-point ZQ calibration with offset cancellation is implemented to improve the level separation mismatch ratio. Designed using 65-nm CMOS technology, the transmitter achieved data rates of 16-Gb/s in NRZ mode, 24-Gb/s in PAM-3 mode, and 32-Gb/s in PAM-4 mode.
참고문헌 (10)
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