SPREAD SPECTRUM CLOCK GENERATION CIRCUIT FOR GENERATING CLOCK SIGNAL CHANGED ACCORDING TO PERIOD, JITTER GENERATION CIRCUIT, AND SEMICONDUCTOR DEVICE

• Main Authors: MIYATA SHINJI, SAITOU TERUHIKO, IIJIMA MASAO, MIYAZAKI YUKISATO, OKADA KOUJI
• Format: Patent
• Language: English; Korean
• Published: 03.07.2004
• Edition: 7
• Subjects: AUTOMATIC CONTROL, STARTING, SYNCHRONISATION, OR STABILISATIONOF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES; BASIC ELECTRONIC CIRCUITRY; CODE CONVERSION IN GENERAL; CODING; DECODING; ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; TRANSMISSION

PURPOSE: A spread spectrum clock generation circuit for generating a clock signal changed according to a period, a jitter generation circuit, and a semiconductor device is provided to reduce the electromagnetic wave radiation by using a simple configuration. CONSTITUTION: A spread spectrum clock generation circuit includes a frequency phase comparator, a charge pump, a loop-filter, a spread spectrum modulation circuit, and a clock generator. The frequency phase comparator is used for detecting a difference in phase between a reference clock and a generated clock. A charge pump is used for generating a charge/discharge signal according to the difference in phase detected by the frequency phase comparator. A loop-filter(14) is used for generating a differential signal in accordance with the charge signal. A spread spectrum modulation circuit(22) is used for generating a spread spectrum modulation signal by modulating the differential signal. The clock generator is used for generating the generated clock with a frequency in accordance with the spread spectrum modulation signal. The spread spectrum modulation period of the spread spectrum modulation signal is changed to multiple different periods.