Signal masking method, signal masking circuit, and semiconductor integrated circuit
AssigneeFujitsu Microelectronics Limited
InventorKouji Mizutani
Life of this patent
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Abstract
A signal masking circuit includes a detection circuit, a delayed read data strobe signal generation circuit, a gating circuit, a counting circuit, and a masking circuit. The detection circuit detects a period of a logic “L” of a read data strobe signal. The gating circuit gates a delayed read data strobe signal, and generates a first masked read data strobe signal. The counting circuit counts the falls of the first masked read data strobe signal until the count reaches a predetermined number, and generates a masking signal for masking the first masked read data strobe signal. The masking circuit masks the first masked read data strobe signal, and outputs a second masked read data strobe signal.
Claims14
A signal masking circuit comprising:
- a detection circuit for detecting a period of a logic “L (Low)” preceding a period of a read data strobe signal effective for receiving read data, and generating a gating signal when the period of the logic “L” is equal to or longer than a predetermined period;
- a delayed read data strobe signal generation circuit for generating a delayed read data strobe signal by delaying the read data strobe signal;
- a gating circuit for gating the delayed read data strobe signal upon receipt of the gating signal, and generating a first masked read data strobe signal;
- a counting circuit for counting falls of the first masked read data strobe signal after the gating until counts counted by the counting circuit reaches a predetermined number, and generating a masking signal for masking the first masked read data strobe signal after the counting;
- and
- a masking circuit for masking the first masked read data strobe signal upon receipt of the masking signal, and outputting a second masked read data strobe signal.
A signal masking method comprising:
- detecting a period of a logic “L” preceding a period of a read data strobe signal effective for receiving read data after a lapse of a set period since the rise of a clock signal at which a read command is received;
- generating a delayed read data strobe signal by delaying the read data strobe signal;
- generating a gating signal for gating the delayed read data strobe signal after the period of the logic “L” has reached a predetermined length;
- generating a masked read data strobe signal by gating the delayed read data strobe signal with the gating signal,
- counting of the falls of the masked read data strobe signal after the generating a mask read data strobe signal;
- generating a masking signal for masking the delayed read data strobe signal when the number of counts of the falls of the masked read data strobe signal has reached a predetermined number;
- and
- masking the delayed read data strobe signal with the masking signal to set the logic of the masked read data strobe signal to a fixed value.
The signal masking method according to 13, wherein the predetermined length is specified by the ratio the predetermined length to one cycle of the clock signal.
Dependencies are inferred from the claim text.