Integrated circuit devices that provide constant time delays irrespective of temperature variation

#This application is related to and claims priority from Korean Application No. 2002-19946, filed on Apr. 12, 2002, the disclosure of which is hereby incorporated herein by reference as if set forth in its entirety.

#The present invention is related to integrated circuit devices and, more particularly, to integrated circuit devices including delay circuits that delay an input signal by a predetermined time.

#Signal delay circuits or pulse generating circuits have been used in integrated circuit devices for various purposes, such as signal control. Such signal delay or pulse generating circuits are typically formed using a delay circuit. Generally, the width of a pulse signal is dependant upon a delay time of a delay circuit. Accordingly, it may be important to control the delay time of the delay circuit in order to obtain an accurate pulse width. The delay time may be controlled using a time constant that is determined using the values of one or more resistors and capacitors in the delay circuit. A resistor may be formed of polysilicon, for example, a polysilicon resistor, and a capacitor may be formed using a gate capacitance of a transistor.

#FIG. 1 is a circuit diagram illustrating integrated circuit devices according to embodiments of the present invention;

#FIG. 2 is a diagram illustrating waveforms at nodes of integrated circuit devices according to embodiments of the present invention, for example, embodiments illustrated in FIG. 1;

#FIG. 3A is a diagram illustrating resistance variation of resistive elements according to embodiments of the present invention in accordance with temperature variation; and

#The present invention now will be described more fully with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. In the drawings, when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. Like reference numerals refer to like elements throughout.

#It will be understood that although terms such as first, second etc. are used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Thus, a first element discussed below could be termed a second element, and similarly, a second element may be termed a first element without departing from the teachings of the present invention.

#Embodiments of the present invention will be described below with respect to FIGS. 1 through 3B. Embodiments of the present invention provide delay circuits having a substantially constant time delay irrespective of temperature variation. A resistive means is provided having a substantially constant resistance value irrespective of temperature. In certain embodiments, the resistive means is provided by first and second resistive elements electrically coupled in series having first and second resistance values. In these embodiments, the first resistance value varies in proportion to temperature and the second resistance value varies in inverse proportion to temperature. Thus, a sum of the first and second resistance values may remain substantially constant despite a variation in the temperature of the integrated circuit device. The ability to maintain a substantially constant resistance value may provide a substantially constant time delay for the integrated circuit device because a time constant of the integrated circuit device is partially based on the resistance of the integrated circuit. In particular, the time constant (T) of the integrated circuit device is determined using the equation T=RC, where R is resistance value. Accordingly, integrated circuits according to embodiments of the present invention may provide substantially constant resistance values and/or signal delay times in the presence of temperature variation.