Test circuit and method for multilevel cell flash memory
View Patent ↗A test device and method may be used to detect voltage, current or signals of a digital multilevel memory cell system or to test operation or performance by applying inputted voltages, currents or signals to the memory cell system.
1. A test transceiver comprising:
an ESD pad having a first terminal coupled to an input node and having a second terminal coupled to an output node; and
a resistive circuit having a first terminal coupled to the second terminal of the ESD pad and having a second terminal;
a connection circuit including an output terminal coupled to the first terminal of the resistive circuit, including at least one selection signal terminal; and including at least one internal node that provides signal thereon in response to a selection signal applied to a corresponding selection signal terminal.
2. The test transceiver of claim 1 further comprising:
at least two CMOS transmission gates in series between the internal node and the output node.
3. The test transceiver of claim 1 further comprising:
at least one disabled CMOS transmission gate having one terminal connected to the second terminal of the resistor and having another terminal connected to a power supply.
4. A test circuit comprising:
a first ESD protection circuit coupled to a first node;
a resistor having first and second terminals, said first terminal being coupled to the first node;
a boost circuit having a first terminal coupled to the second terminal of the resistor and having a second terminal coupled to a second node; and
a second ESD protection circuit coupled to the second terminal of the resistor.
5. The test circuit of claim 4 wherein the boost circuit comprising two NMOS transistors coupled in series between first and second terminals thereof.
6. The test circuit of claim 5 wherein the boost circuit comprises:
a clamp circuit coupled to a power supply and a gate of a first NMOS transistor of the boost circuit.
7. The test circuit of claim 5 wherein
a gate of the second NMOS transistor is coupled to a high power supply, and
a source of the second NMOS transistor is coupled to the second terminal of the boost circuit, and
a drain of the second NMOS transistor is coupled to a third terminal of the boost circuit].
8. The test circuit of claim 4 wherein the first ESD protection circuit includes four NMOS transistors coupled in series between ground and a high power supply.
9. The test circuit of claim 8 wherein gates of two NMOS transistors in the middle of the series of NMOS transistors are coupled capacitively to the input pad and coupled resistively to the ground.
10. The test circuit of claim 8 wherein gates of two NMOS transistors in the outside of the series of NMOS transistors are coupled capacitively to the input pad and coupled resistively to the high power supply.