Timing generating apparatus with self-calibrating capability

Details Timing generating apparatus with self-calibrating capability Timing generating apparatus with self-calibrating capability

2000-12-27

2001-10-16

Ton, My-Trang Nu (Department: 2816)

Miscellaneous active electrical nonlinear devices, circuits, and

Signal converting, shaping, or generating

Synchronizing

Reexamination Certificate

active

06304119

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a timing generating apparatus, more particularly to a timing generating apparatus with self-calibrating capability.
2. Description of the Related Art
A timing generator is generally used to provide a timing pulse signal to an IC automatic test equipment (ATE) such that modules of the IC ATE can operate according to the timing pulse signal. Since IC ATE needs to test various IC products, the timing generator must provide accurate timing pulses to conform with a wide range of IC products. Recently, CMOS components are used in the IC ATE. However, due to changes in temperature, CMOS components will experience timing variation such that a compensation or calibration circuit is needed.
Referring to
FIG. 1
, a conventional timing generating apparatus is shown to include a master timing module
10
, and a plurality of slave timing modules
11
, each of which is coupled electrically to the master timing module
10
. The master timing module
10
receives an external reference clock, and generates a plurality of coarse timing pulse signals. Each of the slave timing modules
11
receives the coarse timing pulse signals, and is operable so as to generate a fine timing pulse signal according to a selected one of the coarse timing pulse signals. For example, the coarse timing pulse signals have different time periods, such as 1.0 ns, 2.0 ns, 3.0 ns, . . . . The slave timing modules can generate a plurality of timing pulse signals with different adjustments in time periods, such as 0.05 ns, 0.10 ns, 0.15 ns, . . . . When the conventional timing generating apparatus needs to generate a timing pulse signal with a time period of 6.12 ns, the coarse timing pulse signal with a time period of 6.0 ns is selected by one of the slave timing modules
11
that generates a phase delay of 0.12 ns.
FIG. 2
illustrates an embodiment of the conventional timing generating apparatus. The master timing module
10
is a phase locked ring oscillator that is a closed-loop system. The slave timing module
11
is composed of a programmable delay unit that is an open-loop system and that is unable to maintain the accuracy of the fine timing pulse signal.
FIG. 3
illustrates another embodiment of the conventional timing generating apparatus. In
FIG. 3
, unlike the embodiment of
FIG. 2
, the slave timing module
11
′ is implemented as a phase locked delay line for generating the fine timing pulse signal from the coarse timing pulse signal via a phase selection multiplexer
111
. While the fine timing pulse signal can be obtained from the slave timing module
11
′, it is noted that the phase selection multiplexer
111
and drivers are outside of a phase locked loop of the phase locked delay line. Therefore, the accuracy of the fine timing pulse signal is affected by the high temperature coefficient of solid state devices such that a temperature compensation mechanism is needed to maintain the accuracy of the fine timing pulse signal at different temperatures.
SUMMARY OF THE INVENTION
Therefore, the object of the present invention is to provide a timing generating apparatus with self-calibrating capability that has a relatively high accuracy and that can be produced at a relatively low cost.
According to the present invention, a timing generating apparatus includes a master timing module, a slave timing module and a calibration module.
The master timing module is adapted to receive an external reference clock and to generate a coarse timing pulse signal therefrom.
The slave timing module is coupled electrically to the master timing module so as to receive the coarse timing pulse signal therefrom, and is operable so as to generate a fine timing pulse signal from the coarse timing pulse signal.
The calibration module is coupled electrically to the master timing module and the slave timing module. The calibration module receives the coarse timing pulse signal and the fine timing pulse signal, determines a phase difference value between the coarse timing pulse signal and the fine timing pulse signal, and generates a phase compensation signal corresponding to difference between the phase difference value and a predetermined phase difference value.
The slave timing module includes a delay control unit that receives the phase compensation signal from the calibration module, and that generates a delay voltage signal corresponding to the phase compensation signal, and a voltage-controlled delay unit that receives the coarse timing pulse signal and the delay voltage signal, and that introduces a phase delay corresponding to the delay voltage signal into the coarse timing pulse signal so as to generate the fine timing pulse signal.


REFERENCES:
patent: 5214680 (1993-05-01), Gutierrez, Jr. et al.
patent: 5243227 (1993-09-01), Gutierrez, Jr. et al.
patent: 5710744 (1998-01-01), Suda
patent: 6247138 (2001-06-01), Tamura et al.

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