DRAM boosted voltage supply
View Patent ↗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.
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.
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.
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.
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.