Title:
プログラマブルデュアルエッジトリガードカウンター
Document Type and Number:
Japanese Patent JP5059828
Kind Code:
B2
Abstract:
A counter for synthesizing clock signals with minimal jitter analyzes an ongoing count to determine whether the rising edge of an output clock should be triggered by the rising edge or falling edge of an input clock signal and to further determine whether the falling edge of the output clock should be triggered by the rising or the falling edge of the falling edge of the input clock signal. The counter may be implemented as a M/N:D counter in which a phase accumulator is compared to predetermined values to select the rising and falling edges of the output clock signal. In a default condition, the rising and falling edges of the output clock signal are triggered by rising edges of the input clock signal. However, if the accumulated phase value is greater than or equal to M/2 and less than M, an overriding signal will trigger the rising edge of the output clock based on the falling edge of the previous input clock cycle. If the accumulated phase value is greater than or equal to D+M/2 and less than M, the falling edge of the output clock is triggered by the falling edge of the preceding input clock signal. The use of rising and falling edges of the input clock signal reduces the jitter in the output clock signal and improves the duty cycle resolution. In addition, the clock circuit can produce a modulo-n signal with a 50% duty cycle. The designed architecture also produces an inverted output clock signal whose characteristics are identical to the non-inverted output clock signal (with the exception of duty cycle, which is inverted).
Inventors:
Matthew El. Severson
Application Number:
JP2009237690A
Publication Date:
October 31, 2012
Filing Date:
October 14, 2009
Export Citation:
Assignee:
QUALCOMM INCORPORATED
International Classes:
H03K23/64; H03K3/02; H03K5/1532; H03K5/156; H03K21/10; H03K23/68
Attorney, Agent or Firm:
Kurata Masatoshi
Satoshi Kono
Makoto Nakamura
Yoshihiro Fukuhara
Takashi Mine
Toshio Shirane
Sadao Muramatsu
Nobuhisa Nogawa
Kocho Chojiro
Naoki Kono
Katsu Sunagawa
Katsumura Hiro
Shoji Kawai
Tatsushi Sato
Takashi Okada
Mihoko Horiuchi
Takenori Masanori
Takuzo Ichihara
Yamashita Gen
Satoshi Kono
Makoto Nakamura
Yoshihiro Fukuhara
Takashi Mine
Toshio Shirane
Sadao Muramatsu
Nobuhisa Nogawa
Kocho Chojiro
Naoki Kono
Katsu Sunagawa
Katsumura Hiro
Shoji Kawai
Tatsushi Sato
Takashi Okada
Mihoko Horiuchi
Takenori Masanori
Takuzo Ichihara
Yamashita Gen