Abstract: A conditional clock gate is implemented that equalizes load conditions on clocked transistor gates to provide a better quality clock signal in a clock distribution network. The conditional clock gate may be implemented as either a NAND gate or a NOR gate. According to one embodiment, a pre-charge transistor is that equals clock loading when the enable signal is deasserted. The pre-charge transistor charges a terminal of a clocked transistor during certain clock states to mimic load conditions that exist when the enable signal is asserted. In another embodiment, a pre-discharge transistor is implemented that charges a terminal of a clocked transistor during certain clock states to mimic load conditions that exist when the enable signal is asserted. Conditional clock gates may also be implemented with multiple enable inputs using these same principles.

Abstract: A multi-ported SRAM memory cell includes a pair of inverters that holds the data bit. The state terminals of the memory cell connect via a separate read and write data path to the bit lines. The read bit lines connect to a pull-down transistor stack. The first transistor in the stack is gated by the word line, and the second transistor is gated by the state terminal of the memory cell. If the word line is asserted and the second transistor is turned on by the state of the memory cell, the bit line is connected to ground, thus pulling the bit line low. Conversely, if the second transmitter is not turned on, the bit line stays at a high voltage level. In a preferred embodiment, the memory cell is isolated from the pull-down transistor stack by an isolation buffer, such as an inverter, which inverts the voltage on the state terminal of the memory cell.