Lucent Technologies Inc.

Xianguo Cao

Obed Duardo

Bo Ye

A delay compensation circuit that determines the effects of process, voltage, and temperature (PVT) conditions of a chip by measuring the effective delay time of delay components inside the chip. The delay compensation circuit includes a plurality of sampler modules, each of which receives a delayed clock signal from one of a series of delay cells within a tapped delay circuit. The delay compensation circuit generates an output value based on the total number of sampling modules that lock into a fixed input signal using the delayed clock signals. Since the delay time of each delay cell changes based on variations of PVT conditions, the output values generated by the delay compensation circuit are determinate of PVT conditions in the chip. These output values can be used to design components to compensate for variances in PVT conditions or to control a variable delay component based on detected PVT conditions.

Delay compensation circuit

An apparatus including first and second devices, at least one connection between an input of the second device and an output of the first device, and at least one resistor in series between the connection and the input of the second device. The series resistor, acting as a type of end termination, positively alters the waveforms of the signals input to the second device. In particular, glitches and ringing after the input pin package or at the input of the second device (at the gate for a CMOS transistor) are reduced. Overshoots and undershoots are also reduced. As a result, the input signals are usable and the interface between the first and second devices operates correctly. Further, the setup procedure of the valid logic level of the input signal can be accomplished much more quickly and is much more stable. The series resistor also consumes very little extra power.

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