Dynamic memory word line driver scheme
First Claim
1. An apparatus for selecting a word line and writing to memory cells in a dynamic random access memory (DRAM), the apparatus comprising:
- a level shifter circuit including at least first and second transistors having their respective sources directly connected to a controlled high supply voltage level Vpp supplied from a high voltage supply, the level shifter circuit being configured to;
respond to a decoded address input signal selectively having logic voltage levels that are less than the controlled voltage level Vpp, the drain of the first transistor being configured to apply current to a first node, the drain of the second transistor being configured to apply current to a second node, the first and second transistors being gated from the second and first nodes, respectively, andproduce a control signal selectively having the controlled high supply voltage level Vpp or a Vss voltage level; and
a driving circuit to drive a selected word line to the controlled high supply voltage level Vpp in response to the control signal to write a logic voltage level in a DRAM cell storage capacitor associated with the selected word line.
3 Assignments
0 Petitions
Accused Products
Abstract
A circuit which accurately controls the word line (pass transistor gate) driving voltage to a voltage which is both controlled and is not significantly greater than is needed to drive the word line. The circuit eliminates the need for a double-boot-strapping circuit, and ensures that no voltages exceed that necessary to fully turn on a memory cell access transistor. Voltages in excess of that which would reduce reliability are avoided, and accurate driving voltages are obtained. A DRAM includes word lines, memory cells having enable inputs connected to the word lines, a gate receiving word line selecting signals at first logic levels Vss and Vdd, and for providing a select signal at levels Vss and Vdd, a high voltage supply source Vpp which is higher in voltage than Vdd, a circuit for translating the select signals at levels Vss and Vdd to levels Vss and Vpp and for applying it directly to the word lines whereby an above Vdd voltage level word line is achieved without the use of double boot-strap circuits.
181 Citations
21 Claims
-
1. An apparatus for selecting a word line and writing to memory cells in a dynamic random access memory (DRAM), the apparatus comprising:
-
a level shifter circuit including at least first and second transistors having their respective sources directly connected to a controlled high supply voltage level Vpp supplied from a high voltage supply, the level shifter circuit being configured to; respond to a decoded address input signal selectively having logic voltage levels that are less than the controlled voltage level Vpp, the drain of the first transistor being configured to apply current to a first node, the drain of the second transistor being configured to apply current to a second node, the first and second transistors being gated from the second and first nodes, respectively, and produce a control signal selectively having the controlled high supply voltage level Vpp or a Vss voltage level; and a driving circuit to drive a selected word line to the controlled high supply voltage level Vpp in response to the control signal to write a logic voltage level in a DRAM cell storage capacitor associated with the selected word line. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. A dynamic random access memory (DRAM) for storing a voltage level in a memory cell coupled to a word line and a bit line, the DRAM comprising:
-
a level shifter circuit including at least first and second transistors having their respective sources directly connected to a controlled high supply voltage level Vpp supplied from a high voltage supply, the level shifter circuit being configured to; respond to a decoded address input signal selectively having logic voltage levels that are less than the controlled voltage level Vpp, the drain of the first transistor being configured to apply current to a first node, the drain of the second transistor being configured to apply current to a second node, the first and second transistors being gated from the second and first nodes, respectively, and produce a control signal selectively having the controlled high supply voltage level Vpp or a low voltage level; and a driving circuit to drive a selected word line to the controlled high supply voltage level Vpp in response to the control signal to write a logic voltage level in a DRAM cell storage capacitor associated with the selected word line. - View Dependent Claims (8, 9, 10, 11, 12)
-
-
13. A dynamic random access memory (DRAM) comprising a word line driver configured to:
-
receive a word line select address signal having a selected one of a low logic level voltage Vss and a high logic level voltage Vdd, and selectively apply a controlled high supply voltage Vpp to the word line through the source-drain circuit of a P-channel pass FET, the controlled high supply voltage Vpp being substantially equal to or greater than the high logic level voltage Vdd plus one FET threshold voltage (Vdd+Vtn), the controlled high supply voltage Vpp being directly connected to the sources of first and second pull-up FETs, the gate of the second pull-up FET and the drain of the first pull-up FET being coupled to a first node, the gate of the first pull-up FET and the drain of the second pull-up FET being coupled to a second node, the drain of a first pull-down FET being coupled to the first node, the drain of a second pull-down FET being coupled to the second node, the first and second pull-up FETs being gated from the second and first nodes, respectively, in response to the word line select address signal to provide a control signal selectively having the high supply voltage Vpp or a Vss voltage level to the gate of the P- channel pass FET. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
-
Specification