Elpida Memory, Inc.

Longitude Semiconductor S.a.r.l.

Atsuko Monma

Kanji Oishi

To provide a duty detection circuit including: a plurality of duty detectors that detect a duty ratio of internal clocks; a controller that controls the plurality of duty detectors so that the plurality of duty detectors operates in different phases from one another; and an output selecting unit that selects one of duty detection signals from the plurality of duty detectors. According to the present invention, since the duty detectors operate in the different phases from one another, the output selecting unit can output a duty detection signal with a higher frequency than a generation frequency with which each duty detector generates the duty detection signal. Accordingly, when the duty detection circuit according to the present invention is used to adjust a clock of the DLL circuit, a control period of the DLL circuit can be reduced.

Duty detection circuit, clock generation circuit including the duty detection circuit, and semiconductor device

A duty detection circuit includes an integration circuit for receiving an RCLK signal and an FCLK signal that are internal clock signals generated by a DLL circuit, and generating voltage levels in accordance with the duty ratio of these internal clock signals; an amplifier for amplifying the output of the integration circuit; a latch circuit for latching the output of the amplifier; a control circuit for controlling the operation timings of each component; a bias circuit for feeding a BIAS signal to the integration circuit; and a frequency monitor circuit unit for monitoring the frequency of the clock signal. The frequency monitor circuit unit is a circuit component used when the power source is turned on, during resetting, and when other initial settings are performed, and detects the actual frequency of the clock signal and adjusts the amount of charging or discharging of the capacitors Cthrough Cin the integration circuit according to this actual frequency.

Duty detection circuit

The clock delay circuit according to the present invention includes a delay circuit section, a selection circuit section, and jitter suppression elements. The delay circuit section provides a plurality of delay clock signals that are obtained by delaying a clock signal with a different delay amount. The selection circuit section selects and provides any one of a plurality of delay clock signals that are provided from the delay circuit section. The jitter suppression elements are connected in series between the delay circuit section and the selection circuit section. When jitters occur at the time of switching the delay clock signals at the selection circuit section, the jitter suppression elements serve to prevent the propagation of the jitters through the delay circuit section.

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Tokyo, Japan

Atsuko Monma