Comparator for determining process variations

Abstract

A comparison circuit may be fabricated along with a primary circuit on a semiconductor substrate. The propagation delay of a comparison signal across a first path of circuit elements is compared to propagation delays of the comparison signal across a second path of delay elements. As a semiconductor fabrication process varies, the relative propagation delays across the first and second paths will vary in a manner correlative to the process variations. By monitoring the relative propagation delays, the fabrication process may be controlled to ensure that the process does not vary to an undesirable extent. Also, various programmable delay elements may be fabricated into the primary circuit, and these programmable delay elements may be activated and / or deactivated in response to the relative propagation delays of the comparison circuit.

Description

[0001] 1. Field of the Invention[0002] The present invention relates generally to electronic circuitry and, more particularly, to a method and apparatus for comparing signal propagation delay across one circuit path with signal propagation delay across another circuit path.[0003] 2. Description of the Related Art[0004] This section is intended to introduce the reader to various aspects of art which may be related to various aspects of the present invention which are described and / or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.[0005] Microprocessor-controlled integrated circuits are used in a wide variety of applications. Such applications include personal computers, vehicle control systems, telephone networks, an...

AI Technical Summary

Problems solved by technology

As the density of memory arrays increases, the cost of the memory tends to decrease while the speed of the memory tends to increase.

However, as the density of a memory, or any other semiconductor device for that matter, increases, the dimensions of the individual elements which make up the semiconductor device tend to decrease.

As these dimensions become increasingly smaller, it becomes more and more difficult to fabricate the elements accurately.

Conversely, as gate dimensions become larger, or as the gate oxide becomes thicker, the transistor tends to operate slower.

Thus, as signals propagate through sequential elements in the circuit, time delays are introduced along each signal path.

A difference in time delays of signal propagation along different paths may cause a malfunction of a circuit that is typically referred to as a "race."

Thus, in a circuit having two or more signal propagation paths that are designed to coordinate to produce a desired function, the circuit may malfunction depending on which path of gates works faster.

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