摘要:
A cache TAG RAM (20) has a TAG array (22, 24) for storing TAG addresses of data stored in a cache memory, and a valid bit array (26, 31). In the cache TAG RAM (20), a valid bit is set for each TAG address to indicate if the TAG address is valid. The valid bit array (26, 31) is located separate from the TAG array (22, 24). During power-up of the cache TAG RAM (20), a multiple step invalidation cycle is used to sequentially invalidate groups of columns of the valid bit array (26, 31). The multiple step invalidation cycle reduces the peak current during an invalidation cycle, thus reducing metal migration.
摘要:
A power-on reset circuit (30) for a memory (20) includes a DC model circuit (39), an N.sub.BIAS check circuit (64), and a NAND logic gate (71). A logic low power-on reset signal is provided at power-up of the memory (20) to establish initial conditions in a clock circuit (29) and in row and column predecoders/latches (24, 27). When the power supply voltage, a bandgap reference voltage, and a bias voltage all reach their predetermined voltages, the power-on reset circuit (30) provides a logic high power-on reset signal. In this manner, the power-on reset circuit (30) is assured of providing a logic low power-on reset signal until all of the proper voltage levels are reached. In addition, the power-on reset circuit models a DC circuit equivalent of an address buffer circuit (79) for compensating for process and temperature variations.
摘要:
A BICMOS output buffer circuit (20) has a voltage converter (21), a reference voltage circuit (28), a driver circuit (24), and a clamping circuit (40). The reference voltage circuit (28) receives a regulated voltage and provides a reference voltage having a low voltage level and a high voltage level. The low voltage level and the high voltage level control the logic high voltage of an output data signal. During a transition from a logic low voltage to a logic high voltage of the output data signal, the output data signal is allowed to overshoot the low voltage level. After the transition is complete, the output data signal settles at the high voltage level. This limits the amount of overshoot of the output data signal. The clamping circuit (40) dampens the oscillations of the output signal.