1. Field of the Invention
The present invention relates to a reference voltage generation circuit capable of generating a reference voltage having multiple steps by using a periodic response characteristic of a chaotic circuit.
2. Background of the Related Art
The comparator is a circuit for comparing a reference voltage and an input voltage and operates as a voltage level detector. Conventionally, a related art comparator includes a 74-series operational amplifier and a plurality of variable resistors.
FIG. 1 illustrates a related art comparator circuit. As shown therein, the comparator includes an operational amplifier OP and three variable resistors R1 through R3. The operational amplifier OP is connected between a power voltage V.sub.CC and a ground voltage V.sub.EE, and receives an input voltage V.sub.IN at an inverting input terminal (-) thereof. The variable resistors R1, R2 and R3 are connected in series between the power supply voltage V.sub.CC and the ground voltage V.sub.EE. A terminal which commonly connects variable resistor R2 and variable resistor R3 is connected with a non-inverting input terminal (+) of the operational amplifier OP. In the drawings, U+ denotes a reference voltage which is applied to the non-inverting (+) input terminal of the operational amplifier OP. A terminal which commonly connects variable resistor R1 and variable resistor R2 is connected with the output terminal of the operational amplifier OP.
The operation of the related art comparator circuit will now be described. As shown in FIG. 1, the operational amplifier OP compares the externally applied input voltage V.sub.IN with the reference voltage U+ and outputs an output voltage V.sub.OUT. If the input voltage V.sub.IN is greater than the reference voltage U+, the output voltage V.sub.OUT becomes the ground voltage -V.sub.EE. If, however, the input voltage V.sub.IN is less than the reference voltage U+, the output voltage V.sub.OUT becomes the power supply voltage V.sub.CC. Thus, EQU V.sub.IN &gt;U+, V.sub.OUT =-V.sub.EE EQU V.sub.IN &lt;U+, V.sub.OUT =V.sub.CC
However, the reference voltage U+ of the conventional comparator is variable in accordance with variable resistors R1 through R3 forming a voltage divider circuit. Thus, ##EQU1##
As described above, the related art comparator has various disadvantages. In accordance with Equation 1, since the related art reference voltage U+ varies in accordance with the variable resistors R1 through R3, the reference voltage U+ becomes unstable, making it difficult to properly operate the comparator.
The above references or above related art are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.