摘要:
A clock buffer includes: a comparator circuit comparing complementary clock signals CLK and /CLK with each other to output an internal clock signal used in a normal operation; a comparator circuit comparing a reference potential Vref and clock signal CLK with each other; and a comparator circuit comparing reference potential Vref and clock signal /CLK with each other. A phase comparator circuit compares the complementary clock signals with each other in respect to phase. An input/output buffer outputs an output of the phase comparator circuit to a data output terminal in a test mode. Therefore, there can be realized a test mode for performing efficient calibration of a measuring apparatus.
摘要:
Serial write data of the burst length transmitted to a data bus are stored in parallel in latch circuits by a S/P data conversion circuit. In a memory cell array, one row of memory cells and four columns of memory cells are rendered active at the same time. Respective bit lines and latch circuits are connected by a sense amplifier I/O circuit. The write data of the burst length are written into the memory cell array at one time. The data of the bit length read out at one time from the memory cell array are converted into serial data by a P/S data conversion circuit to be transmitted to the data bus.
摘要:
An internal clock signal generating circuit includes a selector, a delay line, a 2-frequency divider, a phase comparator and a shift register. The selector alternately selects an external clock signal and an internal clock signal output from the delay line and outputs the selected signal to the delay line. The delay line receiving the signal delays the external clock signal, and delays the internal clock signal output from itself. The 2-frequency divider divides frequency of the internal clock signal by 2. Phase comparator compares phases of the external clock signal and the output signal from the 2-frequency divider. Delay time of the delay line is adjusted by the phase comparator and the shift register so that the phase difference is made 0.
摘要:
A synchronous semiconductor memory device includes a prefetch selector receiving first and second data respectively read from first and second memory cells corresponding to even and odd addresses for outputting them to a data input/output terminal. The prefetch selector sequentially outputs first and second data to the data input/output terminal in one period of a clock period in the normal operation, determines if the first and second data match in a test mode, and outputs the determination result to the data input/output terminal in one period of the clock period.
摘要:
One strobe signal (QS) is outputted from a group of two adjacent memory chips (MC(i-1), MCi) in each module. In each group, the second memory chip (MCi) receives a data mask signal (DQM(i-1)) inputted to the adjacent first memory chip (MC(i-1)) as a data mask control signal (DQMCi), and stops outputting the strobe signal (QS) when both the data mask signal (DQMi) for the second memory chip (MCi) and the data mask control signal (DQMCi) are activated. Each memory chip (MCi) receives the data mask signal (DQMi) and stops outputting data. In a synchronous DRAM using a strobe signal as a trigger, this configuration allows reduction in the number of strobe signals.