Taiwan Semiconductor Manufacturing Comp. Ltd.

Rob Abbott

Cheng-Hsiang Hsieh

Wei-Li Chen

Chaitanya Palusa

Dirk Pfaff

Po-Hsiang Lan

Fan-ming Kuo

Rolando Ramirez

Muhammad Nummer

A multi-tap Differential Feedforward Equalizer (DFFE) configuration with both precursor and postcursor taps is provided. The DFFE has reduced noise and/or crosstalk characteristics when compared to a Feedforward Equalizer (FFE) since DFFE uses decision outputs of slicers as inputs to a finite impulse response (FIR) unlike FFE which uses actual analog signal inputs. The digital outputs of the tentative decision slicers are multiplied with tap coefficients to reduce noise. Further, since digital outputs are used as the multiplier inputs, the multipliers effectively work as adders which are less complex to implement. The decisions at the outputs of the tentative decision slicers are tentative and are used in a FIR filter to equalize the signal; the equalized signal may be provided as input to the next stage slicers. The bit-error-rate (BER) of the final stage decisions are lower or better than the BER of the previous stage tentative decisions.

Multi-tap decision feed-forward equalizer with precursor and postcursor taps

An optimized pulse shaping clock data recovery system is provided that includes a slicer configured to receive a signal and provide an initial set of tentative decisions to a decision feedforward equalizer, where the decision feedforward equalizer provides a fully equalized output signal. The slicer may be incorporated as part of decision feedback equalizer to provide better quality tentative decisions. The clock data recovery system also receives the first output signal that is partially equalized in such a way as to optimally shape it for a clock to sample it at an ideal location by providing an adjustment signal to the analog to digital controller.

SerDes receiver with optimized CDR pulse shaping

Serdes receiver with optimized CDR pulse shaping

A delay circuit includes a delay line configured to output an output signal by imposing a delay value on an input signal. The delay circuit further includes an arithmetic unit configured to calculate a control code for the delay value based on delay codes. The delay circuit further includes a delay locked loop (DLL) configured to generate the delay codes based on a clock signal. The delay circuit further includes a controller configured to suspend operation of the DLL when the clock signal operates at a first frequency, to set the DLL to operate based on a second frequency when the DLL is suspended, and to resume operation of the DLL when the clock signal operates at the second frequency without the need to relock the DLL.

DLL calibration method for fast frequency change without re-locking

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Rob Abbott