A method of testing non-volatile memory cells formed on a die includes erasing the memory cells and performing a first read operation to determine a lowest read current RC1 for the memory cells and a first number N1 of the memory cells having the lowest read current RC1. A second read operation is performed to determine a second number N2 of the memory cells having a read current not exceeding a target read current RC2. The target read current RC2 is equal to the lowest read current RC1 plus a predetermined current value. The die is determined to be acceptable if the second number N2 is determined to exceed the first number N1 plus a predetermined number. The die is determined to be defective if the second number N2 is determined not to exceed the first number N1 plus the predetermined number.

A data sampling circuit includes a frequency dividing circuit, a sampling circuit and a selection circuit. The frequency dividing circuit is configured to receive a first data sampling signal, and perform frequency dividing processing on the first data sampling signal to obtain multiple second data sampling signals associated with respective phases; the sampling circuit is configured to receive the multiple second data sampling signals and a first data signal, and sample the first data signal according to the multiple second data sampling signals to obtain multiple second data signals associated with respective phases; and the selection circuit is configured to receive preamble information and mode register set (MRS) information, and select among the multiple second data sampling signals and the plurality of second data signals according to the preamble information and the MRS information to obtain a target data sampling signal and a target data signal respectively.

A method for testing a circuit includes performing, by a test engine, a test of bit write to a memory. The test includes defining a bit group based on a set of bits from an address of a memory location. The test further includes generating a bit mask for the bit group. The test further includes performing a bit write operation to the address to store a sequence of bits, the sequence of bits selected using a predetermined bit pattern. The test further includes reading content of the address. The test also includes comparing, using the bit mask, only bits corresponding to the bit group from the sequence of bits and from the content of the address.

An integrated circuit includes a memory and a memory test circuit, which when invoked to test the memory, is configured to generate one or more March tests applied to the memory. The memory test circuit is further configured to construct a table including a first index, a second index, and a first March test of the one or more March tests. The first index is associated with one or more families each characterized by a different length of the one or more March tests. The second index is associated with one or more mechanisms each characterized by a different property of the one or more March tests. The memory test circuit is further configured to generate a second March test from the first March test.

Technology is disclosed herein for a semiconductor die, and controlling operation of the semiconductor die. In some aspects, a semiconductor die is configured to test an I/O circuit on the semiconductor die. The semiconductor die has an input circuit that compares a voltage signal at one of a first input or a second input with a reference voltage at the other of the first input or the second input to generate an input voltage signal. The first input may be connected to an I/O contact. During a normal mode a control circuit on the die provides a reference voltage to second input. During a test mode, the control circuit internally loops back a test signal from an output circuit to the second input of the input circuit. Thus, the test signal avoids the I/O contact.

A memory device that includes a plurality of non-volatile memory cells and a controller. The controller is configured to erase the plurality of memory cells, program each of the memory cells, and for each of the memory cells, measure a threshold voltage applied to the memory cell corresponding to a target current through the memory cell in a first read operation, re-measure a threshold voltage applied to the memory cell corresponding to the target current through the memory cell in a second read operation, and identify the memory cell as defective if a difference between the measured threshold voltage and the re-measured threshold voltage exceeds a predetermined amount.

A test system is provided that includes a memory test circuit, a memory, an input logic circuit, a bypass circuit, an output logic circuit and a register. The register is operated as a pipeline register of the memory test circuit and the output logic circuit. In a first test mode, the memory test circuit transmits a first test signal to the memory such that the memory outputs a memory output test signal to be stored in the register and further transmitted to the memory test circuit or the output logic circuit to perform test.

A method for testing a circuit includes performing, by a test engine, a test of bit write to a memory. The test includes defining a bit group based on a set of bits from an address of a memory location. The test further includes generating a bit mask for the bit group. The test further includes performing a bit write operation to the address to store a sequence of bits, the sequence of bits selected using a predetermined bit pattern. The test further includes reading content of the address. The test also includes comparing, using the bit mask, only bits corresponding to the bit group from the sequence of bits and from the content of the address.

A test system for a memory card includes a first circuit board. One side of the first circuit board is provided with a plurality of contact groups spaced apart from each other along a row direction. Another side of the first circuit board is provided with slots disposed along the row direction. The test system further includes a second circuit board. The second circuit board is provided with a test circuit, and is inserted into the slot along a direction perpendicular to the first circuit board. The second circuit board provides a test signal to the contact groups.

Technology is disclosed herein for a semiconductor die, and controlling operation of the semiconductor die. In some aspects, a semiconductor die is configured to test an I/O circuit on the semiconductor die. The semiconductor die has an input circuit that compares a voltage signal at one of a first input or a second input with a reference voltage at the other of the first input or the second input to generate an input voltage signal. The first input may be connected to an I/O contact. During a normal mode a control circuit on the die provides a reference voltage to second input. During a test mode, the control circuit internally loops back a test signal from an output circuit to the second input of the input circuit. Thus, the test signal avoids the I/O contact.