Nobuaki Matsudaira

An adaptive pre-emphasis technique with opposite directional training

This paper presents a novel adaptive pre-emphasis technique for half-duplex communication in asymmetric systems between electronic control units (ECUs) and automotive actuators. Both an adaptive decision feedback equalizer (DFE) and a DFE-like pre-emphasis circuit are implemented in only ECU side in order to compensate frequency dispersion of the automotive-grade harness. By transmittng the traning pattern from the actuator, the coefficients of both DFE and DFE-like pre-emphasis circuit are determined, providing the same equalization characteristics. The proposed pre-emphasis technique enables the actuator to receive already equalized signals without equalization circuit in it. Our simulation results demonstrate more than 200% improvement of the eye openinig for 400Mbps communication with a 5-m harness of more than 10-dB dispersion at the Nyquist frequency.

An over-sampling adaptive pre-emphasis technique for multi-drop bus communication system

This paper presents an over-sampling adaptive pre-emphasis technique for multi-drop bus communication between electronic control unit (ECU) and automotive actuators. Each actuator transmits the training pattern separately and decision feedback equalizer (DFE) in ECU analyzes the transmission characteristic of each path. DFE-like pre-emphasis circuit transmits the pre-emphasized signal to compensate the loss of transmission line. In actuator side, there is no equalization circuit because it receives equalized signal. Since this architecture employs an oversampling DFE and low pass filter for bandwidth limitation, ECU can provide the wide opening eye pattern even in multi-drop topology which has sharp drop in the transmission characteristic due to stub. In our simulation results, it can equalize the eye to the 0.06 UI jitter and 81 % eye height in the 3m stub multi-drop topology at 50 Mbps.

A 10-bit fast lock data recovery compensating pulse-width distortion for isolated data communications

This paper presents a fast lock data recovery, which can compensate pulse-width distortion of the data signal waveform caused by the optocoupler. The proposed technique exploits the nature that only the rising edges of the data have a fixed amount of time delay at the output of the optocoupler. This delay is cancelled out by a recursive digital calculation after the bit number estimation using the blind oversampling. An experimental prototype fabricated in an in-house 40-V 0.8-um SOI BCD automotive process compensates more than ±50% pulse-width distortion with only 10-bit training as a preamble pattern. It can be applied with an inaccurate CR oscillator with 0.17-UI (unit interval) peak-to-peak jitter and up to ±10% frequency offset between the transmitter and the receiver.