Spread spectrum clock generation circuit, jitter generation circuit and semiconductor device
AssigneeFujitsu Limited
InventorsShinji Miyata, Kouji Okada, Masao Iijima, Teruhiko Saitou, Yukisato Miyazaki
Life of this patent
Estimating the term…
Abstract
A spread spectrum clock generation circuit capable of further reducing the electromagnetic wave radiation with a simple configuration has been disclosed and, particularly in a spread spectrum clock generation circuit using a current control oscillator (ICO), a differential signal to which a spread spectrum modulation signal, the period or amplitude of which changes, is added is generated, and the differential signal is applied to the ICO and a clock is generated.
Claims7
A spread spectrum clock generation circuit comprising a frequency phase comparator for detecting a difference in phase between a reference clock and a generated clock, a charge pump for generating a charge/discharge signal in accordance with the difference in phase detected by the frequency phase comparator, a loop-filter for generating a differential voltage signal in accordance with the charge signal, a voltage-current conversion circuit for converting the differential voltage signal into a differential current signal, and a clock generator for generating a generated clock with a frequency in accordance with the differential current signal, wherein a spread spectrum modulation circuit for generating a spread spectrum modulation signal by modulating the differential current signal and an amplifier circuit for amplifying the spread spectrum modulation signal are comprised and the amplified spread spectrum modulation signal is added to the differential current signal and applied to the clock generator.
A spread spectrum clock generation circuit comprising a frequency phase comparator for detecting a difference in phase between a reference clock and a generated clock, a charge pump for generating a charge/discharge signal in accordance with the difference in phase detected by the frequency phase comparator, a loop-filter for generating a differential voltage signal in accordance with the charge signal, a voltage-current conversion circuit for converting the differential voltage signal into a differential current signal, and a clock generator for generating a generated clock with a frequency in accordance with the differential current signal, wherein an amplifier circuit for amplifying the differential current signal and a spread spectrum modulation circuit for generating a spread spectrum modulation signal by modulating the amplified differential current signal are comprised and the spread spectrum modulation signal is added to the differential current signal and applied to the clock generator.
Dependencies are inferred from the claim text.