Fujitsu Corporation

Fujitsu Microelectronics Limited

Nobutaka Taniguchi

Hiroyoshi Tomita

Yasurou Matsuzaki

Yasuharu Sato

Atsushi Takeuchi

Atsushi Hatakeyama

Kuninori Kawabata

Naoharu Shinozaki

Akira Kikutake

Toshimi Ikeda

Yoshihide Bando

Waichirou Fujieda

Yoshihiro Takemae

Masao Nakano

Takaaki Suzuki

Kenichi Kawasaki

Yasuhiro Fujii

Kotoku Sato

Masafumi Yamazaki

Kota Hara

Kazuhiro Ninomiya

A delay time adjusting method adjusts a delay time of an input signal so that a phase of the input signal and a phase of an output signal match each other. The delay time adjusting method comprises the step of delaying the phase of the output signal until a phase difference between the phase of the input signal and the phase of the output signal becomes N periods, where N is an integer other than zero.

Delay time adjusting method of delaying a phase of an output signal until a phase difference between an input signal and the output signal becomes an integral number of periods other than zero

A nonvolatile semiconductor memory device includes a plurality of memory cells holding memory cell information, a plurality of bit lines connected to the plurality of memory cells, the plurality of bit lines including a first bit line conected to a selected one of the plurality of memory cells and a plurality of second bit lines connected to non-selected memory cells, a plurality of reference cells supplying different reference currents respectively, and a read-out circuit, wherein, when reading the memory cell information, the read-out circuit is coupled to the first bit line connected to the selected memory cell and coupled to one of the plurality of reference cells through one of the plurality of second bit lines connected to the non-selected memory cells.

Multi-value nonvolatile semiconductor memory device equipped with reference cell and load balancing circuit

A memory device has a data line (DATA-BUS) for connection to a memory cell, a reference line (Reference-BUS) for reference, a precharge circuit (), a load circuit (), and an amplifier circuit (). The precharge circuit is connected to the data line and the reference line and configured to precharge the data line and the reference line. The load circuit is connected to the data line and the reference line and configured to apply a first constant current to the data line and apply a second constant current which is smaller than the first constant current to the reference line. The amplification circuit is connected to the data line and the reference line and configured to amplify a differential voltage between the data line and the reference line.

Memory device

In the present invention, an external power source supplied to an integrated circuit device is divided into a first external power source for the DLL circuit and a second external power source for circuits other than the DLL circuit. According to the present invention, it is arranged that power source noise generated in the second external power source cannot be transmitted to the variable delay circuit by utilizing the first external power source preferably for the variable delay circuit of the DLL circuit and even more preferably for its delay unit. Also, preferably, it is arranged that power source noise generated in the second external power source cannot be transmitted to the phase coincidence detection unit by utilizing the first power source for the phase coincidence detection unit in the phase comparison circuit of the DLL circuit. Also, by connecting the first external earthing power source to the variable delay circuit and/or phase coincidence detection unit, the effect of power source noise from the second external earthing power source originating from the operation of circuits other than these is suppressed.

Integrated circuit device incorporating DLL circuit

A semiconductor device receiving a stable external power voltage includes a reduced-voltage-generation circuit which generates an internally reduced power voltage, an input circuit which operates based on the internally reduced power voltage, causing the internally reduced power voltage to fluctuate, a clock-control circuit which generates an internal clock signal, an output circuit which outputs a data signal to an exterior of the device at output timings responsive to the internal clock signal, a clock-delivery circuit which conveys the internal clock signal from the clock-control circuit to the output circuit, and operates based on the external power voltage such as to make the output timings substantially unaffected by fluctuation of the internally reduced power voltage.

Semiconductor device using external power voltage for timing sensitive signals

The present invention has a hierarchical DLL circuit comprising a rough DLL circuit for phase adjustment by rough delay unit and a fine DLL circuit for phase adjustment by smaller, fine delay unit. When phase adjustment begins, only the rough DLL circuit operates; when the rough DLL circuit locks on, phase adjustment by the rough DLL circuit ends and the delay amount of the rough DLL circuit is set. When the rough DLL circuit locks on, the fine DLL circuit is caused to operate. In this way, the phase of the timing clock generated by the DLL circuit is adjusted only by fine delay units even if the phase of the reference clock is temporarily shifted by a large amount due to power source noise or the like. Consequently, in the event of temporary phase shifting, the amount of jitter in the timing clock can be suppressed to the small amount of a fine delay unit. Phase adjustment by the rough DLL circuit is stopped by ending phase comparison by the phase comparison circuit, or ending the input of the clock to the phase comparison circuit, for example.

Timing clock generation circuit using hierarchical DLL circuit

A semiconductor integrated circuit device includes a first delay circuit delaying a first clock signal, a second delay circuit delaying a second clock signal which has an inverted phase with respect to the first clock signal, a phase comparator outputting a phase error signal based on a comparison of the first clock signal and a feedback signal corresponding to an output signal from the first delay circuit, a delay control circuit generating a delay control signal based on the phase error signal, for variably controlling a delay quantity of the first and second delay circuits, and a timing adjusting circuit variably controlling a delay quantity of the second delay circuit by supplying the delay control signal to the second delay circuit at a timing synchronized to the second clock signal.

Semiconductor integrated circuit device

The present invention omits a variable delay circuit (,in FIG. 1) inside a DLL circuit, and instead, creates a timing synchronization circuit, which generates a second reference clock. The timing synchronization circuit shifts the phase of a first reference clock generated by a frequency divider to the timing of a timing signal generated from the other variable delay circuit so that the second reference clock matches to the timing signal. Then, a phase comparator compares the divided first reference clock to a variable clock that delays the second reference clock, and controls the delay time of the variable delay circuit so that both clocks are in phase. As a result, one variable delay circuit can be omitted, and a DLL circuit that uses a divided clock can be configured.

Integrated circuit device

A semiconductor integrated circuit device includes a DLL circuit. The DLL circuit includes a frequency divider which frequency-divides an input clock at a frequency dividing ratio which is varied depending on a frequency of the input clock and thus results in a dummy clock and a reference clock. A delay system includes a variable delay circuit which delays the dummy clock. A control circuit controls a delay amount of the variable delay circuit so that a phase of a delayed dummy clock from the delay system and the reference clock becomes zero.

A method of measuring a time which a timing-stabilization circuit requires in order to complete timing stabilization with regard to a semiconductor device provided with a first function to reset the timing-stabilization circuit and a second function to output a signal indicative of completion of the timing stabilization is disclosed. The method includes the steps of a) activating the timing-stabilization circuit, b) detecting a timing of the completion of the timing stabilization by using the second function, and c) measuring the time which the timing-stabilization circuit requires to complete the timing stabilization based on the timing.

Semiconductor device having timing-stabilization circuit and method of

A semiconductor integrated circuit is adapted to make invalid an external clock, externally supplied to the semiconductor integrated circuit, when the semiconductor integrated circuit is set in an active power-down state. The semiconductor integrated circuit includes a delay locked loop DLL circuit which outputs an internal clock which phase is synchronized to the external clock. A latch circuit retains control signals in synchronism with the internal clock output by the DLL circuit. An internal circuit performs a predetermined process based on the control signals supplied from the latch circuit.

Semiconductor integrated circuit

In a semiconductor memory device operable in synchronism with a clock signal externally supplied thereto, there are provided a first part which detects a state of a predetermined signal after a given command is input to the semiconductor memory; and a second part which sets, on the basis of the state of the predetermined signal, the semiconductor memory device to a self-refresh mode in which a refresh operation is carried out without an external signal.

Growing community of inventors

Kawasaki, Japan

Nobutaka Taniguchi