DRAM boosted voltage supply

• US 6,980,448 B2
• Filed: 06/17/2003
• Issued: 12/27/2005
• Est. Priority Date: 04/06/1990
• Status: Expired due to Fees

• Current Assignee: Mosaid Technologies Incorporated (MOSAID Technologies Inc. (f/k/a Conversant Intellectual Property Management))
• Original Assignee: Mosaid Technologies Incorporated (MOSAID Technologies Inc. (f/k/a Conversant Intellectual Property Management))
• Inventors: Foss, Richard C., Gillingham, Peter B., Harland, Robert F., Lines, Valerie L.
• Primary Examiner(s): Riley, Shawn
• Application Number:
  US10/463,218
• Publication Number:
  US 20040036456A1
• Time in Patent Office: 924 Days
• Field of Search: 363/59, 363/60, 327/111, 327/589, 365/226, 365/203, 365/189.09, 365/149, 365/189.11, 365/230.06, 307/109
• US Class Current: 363/60
• CPC Class Codes: G05F 3/205 Substrate bias-voltage generators for static stores G11C5/146
• CPC Class Codes: G11C 11/4074 Power supply or voltage generation circuits, e.g. bias voltage generators, substrate voltage generators, back-up power, power control circuits
• CPC Class Codes: G11C 11/4085 Word line control circuits, e.g. word line drivers, - boosters, - pull-up, - pull-down, - precharge
• CPC Class Codes: G11C 5/145 Applications of charge pumps; Boosted voltage circuits; Clamp circuits therefor G11C5/141 takes precedence
• CPC Class Codes: G11C 5/147 Voltage reference generators, voltage or current regulators; Internally lowered supply levels; Compensation for voltage drops G11C5/141 takes precedence
• CPC Class Codes: G11C 8/08 Word line control circuits, e.g. drivers, boosters, pull-up circuits, pull-down circuits, precharging circuits, for word lines
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps

Abstract

A circuit for providing an output voltage for a DRAM word line which can be used to drive memory word lines which can be as high as 2V_dd. Transistors in a boosting circuit are fully switched, eliminating reduction of the boosting voltage by V_tn through the transistors. The boosting capacitors are charge by V_dd. A regulator detects conduction current of a replica of a memory cell access transistor, shutting off the boosting circuit clock oscillator when the correct voltage to operate the access transistor has been reached.

Claims

1. A dynamic random access memory (DRAM) having a boosted voltage supply comprising:

a boosting capacitor having first and second terminals; and

a switching circuit including a first transistor between a DC voltage supply and the first terminal of the boosting capacitor and a second transistor between the first terminal of the boosting capacitor and a capacitive load, the first transistor and the second transistor being driven by clock signals derived from an oscillator, the switching circuit alternately connecting the first terminal of the boosting capacitor to the DC voltage supply and to the capacitive load, while alternating the voltage level connected to the second terminal of the boosting capacitor with clocked transistors, to pump the voltage on the capacitive load to a boosted supply voltage greater than and of the same polarity as the DC voltage supply, the second transistor being fully switched to substantially eliminate a threshold voltage reduction of boosted voltage, the boosted supply voltage being supplied to a circuit of the DRAM.

3. A DRAM as claimed in claim 1 wherein the boosted voltage level is supplied to a clock generator for generating boosted clock signals.

4. A DRAM as claimed in claim 1 wherein the boosted voltage level is supplied to a word line decoder.

2. A method of generating a boosted supply voltage in a dynamic ransom access memory (DRAM) comprising:

providing a DC voltage supply and a boosting capacitor having first and second terminals;

with clock signals applied to switches, alternately switching the first terminal of the boosting capacitor to the DC voltage supply and to a capacitive load, while alternating the voltage level connected to the second terminal of the boosting capacitor with clocked transistors, to pump the capacitive load to a boosted supply voltage greater than and of the same polarity as the DC voltage supply, the switch between the first terminal of the boosting capacitor and the capacitive load being fully switched to substantially eliminate a threshold voltage reduction of boosted voltage; and

supplying the boosted supply voltage to a circuit of the DRAM.

5. A method as claimed in claim 2 wherein the boosted voltage level is supplied to a clock generator for generating boosted clock signals.

6. A method as claimed in claim 2 wherein the boosted voltage level is supplied to a word line decoder.