Random number generator with ring oscillation circuit
First Claim
1. A semiconductor apparatus comprising:
- a central processing unit;
a ring oscillator including plural gate circuits; and
a counter circuit,wherein the central processing unit supplies a first signal to the ring oscillator for instructing to start an oscillation, andthe counter circuit counts a number of output signals from the plural gate circuits during a period, which is determined by a time when a metastable state disappears in the ring oscillator, after the ring oscillator receives the first signal.
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Abstract
A random number generator includes a ring oscillator having an EX-OR gate and four inverters together forming a loop. This loop enters stable state for a start signal having the low level and oscillates for the start signal having the high level. When the start signal has a pulse of a width shorter than the loop'"'"'s delay time, output nodes responsively, sequentially enter metastable state hovering between the high and low levels. The metastable waveform becomes smaller with time and finally disappears. As metastable state cannot be controlled in longevity, it disappears at any random number node. A counter thus outputs a signal serving as true random number data depending on the longevity of the metastable state. A random number generator miniaturized and having reduced power consumption, and of high performance can thus be implemented.
25 Citations
4 Claims
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1. A semiconductor apparatus comprising:
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a central processing unit; a ring oscillator including plural gate circuits; and a counter circuit, wherein the central processing unit supplies a first signal to the ring oscillator for instructing to start an oscillation, and the counter circuit counts a number of output signals from the plural gate circuits during a period, which is determined by a time when a metastable state disappears in the ring oscillator, after the ring oscillator receives the first signal. - View Dependent Claims (2, 3, 4)
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Specification