| 摘要 |
<p>A CMOS boost word-line clock and decoder-driver circuit which can be used for CMOS DRAM's with substrate bias in addition to VDD supply. A boost word-line clock circuit including simple CMOS inverters are used for the word-line boost and the possible voltage overshoot, which usually occurs because of capacitor two-way boost, can be completely eliminated. Also, the circuit can be triggered by a single clock.</p><p>A high performance decoder circuit is provided in combination with the aforesaid SMOS boost word-line clock circuit, such decoder using NMOS pass-gate in the decoder driver and providing fast word-line boosting. The timing between the decoder and the word-line clock activation is not crucial.</p><p>In order to boost the word-line below 0 V, a negative substrate bias is provided which avoids the junction forward-biasing due to voltage undershoot below 0 V at NMOS source or drain, thus simplifying the design and speeding up the word-line clock pull-down when compared to the word-line boost clock circuit without using the substrate bias.</p><p>An embodiment is shown in the drawings in which block 11 is a NOR gate which sums the two clock signals ø<Sub>B</Sub> and ø <Sub>AS</Sub>. Blocks 13 and 15 include a chain of delay circuits. Block 17 is a delay circuit for clock signal ø<Sub>B</Sub>. Blocks 19 and 21 also include chains of delay circuits. Block 23 functions as a gate wherein clock signal ø<Sub>C</Sub> is stored at a device Q<Sub>24</Sub> and is gated to delay block 19 when a signal is applied to device Q23.</p><p>Block 25 is a NOR circuit for delayed signal øcfrom block 15 and delayed signal øD from block 21. Block 27 is a NAND circuit for the output of NOR circuit 25 and an external boost output signal (from block 33). Block 29 is an internal boost circuit for node 22 to control the device Q,. Block 31 is a clock driver means and block 22 is an external boosting means. Block 35 performs a NAND function for the delayed øDsignal from block 21 and the delayed øB signal from block 17.</p> |
