Semiconductor storage device

A semiconductor storage device, comprising:

• a selection circuit that, when a first port is selected by a select signal, selects an address signal supplied to the first port, input data supplied to the first port, an operation permission signal supplied to the first port and a read/write control signal supplied to the first port and which, when a second port is selected by the select signal, selects an address signal supplied to the second port, input data supplied to the second port, an operation permission signal supplied to the second port and a read/write control signal supplied to the second port, so as to send the selected address signal, input data, operation permission signal and read/write control signal to a memory circuit;
• a first output buffer for retaining first output data that is read from the memory circuit in accordance with a first output clock signal and for supplying the first output data to the first port;
• a second output buffer for retaining second output data that is read from the memory circuit in accordance with a second output clock signal and for supplying the second output data to the second port;
• and
• a control circuit that generates the select signal, the first output clock signal, the second output clock signal, and a memory clock signal for the memory circuit on the basis of a first clock signal supplied to the first port and a second clock signal supplied to the second port,
• wherein a rising edge or trailing edge of the first clock signal is taken as a reference timing, a first predetermined time is measured from the reference timing, a second predetermined time greater than the first predetermined time is measured from the reference timing and a third predetermined time greater than the second predetermined time is measured from the reference timing, and
• wherein the control circuit includes:
• a first phase adjustment section that generates the select signal for selecting the first port during a first period from elapse of the first predetermined time until the second predetermined time has elapsed and for the selecting the second port during other periods, generates the first output clock signal together with a first delayed clock signal having a first predetermined pulse width during a second period when the first port is selected by the select signal, generates a first delayed signal during a third period from elapse of the second predetermined time until the third predetermined time has elapsed, generates a second delayed clock signal having a second predetermined pulse width while the first delayed signal is being generated, and generates a conflict monitoring signal that is activated during a fourth period from the reference timing until the second predetermined time has elapsed;
• a second phase adjustment section that generates a second delayed signal a fixed time after a rising edge or trailing edge of the second clock signal and generates a third delayed clock signal having a third predetermined pulse width while the second delayed signal is being generated;
• a phase comparison section that, when the second delayed signal is generated while the conflict monitoring signal is being activated, generates a conflict detection signal during a fifth period from a start of generation of the second delayed signal until generation of the first delayed signal is stopped and generates an arbitration signal while the conflict detection signal and the first delayed signal are being generated;
• and
• a selection section that includes a first selector for selecting the second delayed clock signal when the arbitration signal is being generated and for selecting the third delayed clock signal masked by the conflict detection signal when the arbitration signal is not being generated, so as to issue the selected clock signal as the second output clock signal, and a second selector for selecting the first delayed clock signal when the first port is selected by the select signal and for selecting the second output clock signal when the second port is selected by the select signal, so as to issue the selected clock signal as the memory clock signal.