Address transition detector for fast flash memory device
View Patent ↗An address transition detector circuit includes an input node, an output node, a bandgap reference node, and P bias and N bias nodes having voltages derived from the bandgap reference node. First through fifth cascaded inverters are each powered by a p-channel and n-channel MOS bias transistors having their gates coupled respectively to the P bias node and the N bias node. The input of the first inverter is coupled to the input node. First and second capacitors are coupled respectively to ground from the outputs of the first and fourth cascaded inverters. A NAND gate has a first input coupled to the input node, a second input coupled the output of the fifth cascaded inverter, and an output coupled to the output node.
1. An address transition detector circuit including:
an input node;
an output node;
a stable voltage supply node;
a Pbias node having a first voltage derived from a voltage at the stable voltage supply node;
an Nbias node having a second voltage derived from a voltage at the stable voltage supply node, the second voltage being lower than the first voltage;
first, second, third, fourth, and fifth cascaded inverters, the first cascaded inverter coupled to the input node, each cascaded inverter powered by a p-channel MOS bias transistor and an n-channel MOS bias transistor, the gates of each p-channel MOS bias transistor coupled to the Pbias node, the gates of each n-channel MOS bias transistor coupled to the Nbias node, the sources of each p-channel MOS bias transistor coupled to the stable voltage supply node, the sources of each n-channel MOS bias transistor coupled to ground;
a first capacitor coupled between the output of the first cascaded inverter and ground;
a second capacitor coupled between the output of the fourth cascaded inverter and ground;
a NAND gate having a first input coupled to the input node, a second input coupled the output of the fifth cascaded inverter, and an output coupled to the output node.
2. The address transition detector circuit of claim 1 wherein the stable voltage supply node supplies a voltage generated from a bandgap reference voltage.
3. The address transition detector circuit of claim 1 wherein the capacitances of the first capacitor and the second capacitor are substantially equal.
4. The address transition detector circuit of claim 3 wherein the capacitances of the first capacitor and the second capacitor are between about 0.05 pF and about 0.2 pF.
5. The address transition detector circuit of claim 1 wherein the second and fifth inverters are stronger that the first and fourth inverters.
6. The address transition detector circuit of claim 1 wherein the p-channel MOS bias transistors and n-channel MOS bias transistors driving the first and fourth inverters are smaller than the p-channel MOS bias transistors and n-channel MOS bias transistors driving the second and fifth inverters.
7. The address transition detector circuit of claim 1 wherein the p-channel MOS bias transistors are stronger than the n-channel MOS bias transistors.
8. The address transition detector circuit of claim 1 wherein the n-channel MOS bias transistors are stronger than the p-channel MOS bias transistors.
9. The address transition detector circuit of claim 1 wherein:
the first and fourth inverters are identical; and
the second and fifth inverters are identical.
10. The address transition detector circuit of claim 1 wherein the output of the NAND gate is coupled to the output node through an inverting buffer.