A 7.5Gb/s transmitter with self-adaptive FIR

Abstract

This paper presents a transmitter FIR filter and a coefficient adaptation method based on exploration of the receive eye at the far end receiver. This method does not require backchannel or coding overhead and does not involve any proprietary functionality in the far-end SerDes. The transmitter FIR and the proposed adaptation method were proven in a CMOS 65n SerDes over a variety of copper media for data-rates up to 9.4 Gbps.

Reducing data dependent jitter utilising adaptive FIR pre-emphasis in 0.18 μm CMOS

“…These values are consistent when comparing to literature with similar systems and data rates [1], [2]. The receiver on the other hand, being fully functional except for the low quality pulses generated, dissipates 19.8 mW compared to the simulated value of 18 mW.…”

“…Two methods of adaptive pre-emphasis are presented in [16] of which the most feasible is pilot signalling and peak detection, introduced in [17]. Pilot signalling and peak detection works on the basis that by transmitting a pilot signal corresponding to a specific filter tap, the received peak voltage can be compared to an "ideal" received voltage [17], hence a decision can be made regarding the specific filter tap coefficient and can be adjusted accordingly until the optimum value is reached.…”

“…Pilot signalling and peak detection is easier to implement than a least mean squares (LMS) convergence engine, since it uses a low frequency return path and not two identical master-slave transceivers and channels, which is the more popular method for implementing adaptive pre-emphasis [16]. The low frequency feedback path hence requires no careful matching and layout considerations when implementing such a link on a printed circuit board.…”

A 1.62/2.7-Gb/s Adaptive Transmitter With Two-Tap Preemphasis Using a Propagation-Time Detector

“…Several adaptation methods [8]- [12] are widely used to adjust the tap coefficients to compensate the unknown channel loss. In [8]- [10], the back channel or the bidirectional transceiver is needed to process the eye-opening information.…”

“…In [11], the transmitter with an autoconfiguration technique is adopted, but the collaborating receiver is needed. In [12], an adaptation algorithm is used, but the external software and the connection via a serial interface are needed.…”