Abstract: Method and apparatus are disclosed for checking the resistance of antifuse elements in an integrated circuit. A voltage based on the resistance of an antifuse element is compared to a voltage based on a known resistance, and an output signal is generated whose binary value indicates whether the resistance of the antifuse element is higher or lower than the known value of resistance. The method and apparatus are useful in verifying the programming of antifuse elements.

Abstract: A dual mode, full density/half density SDRAM includes a refresh controller specifically adapted to refresh memory cells of the SDRAM in the half density mode at a rate that is significantly slower than the rate at which the memory cells are refreshed in the full density mode. In the half density mode, the refresh controller increments a counter at a rate that is half the rate the counter is incremented in the full density mode. A refresh trigger pulse, which initiates the refresh of the memory cells, is generated when the counter has incremented to one of a first counter stage in the full density mode and a counter stage two stages beyond the first counter stage in the half density mode. Circuitry is also provided for ignoring some auto-refresh commands applied to the SDRAM in the half density mode so that the memory cells are also refreshed less frequently in the auto-refresh mode.

Abstract: Circuitry for programming antifuse elements is provided which permits all antifuse elements in a bank to be programmed simultaneously, thereby enhancing the speed at which antifuse elements may be programmed. In one embodiment, a feedback circuit is associated with each antifuse element to stop the flow of current through the antifuse element once it is programmed. In another embodiment, circuitry is provided for generating a separate programming pulse for each antifuse element, which is selected for programming.

Abstract: A dual mode, full density/half density SDRAM includes a refresh controller specifically adapted to refresh memory cells of the SDRAM in the half density mode at a rate that is significantly slower than the rate at which the memory cells are refreshed in the full density mode. In the half density mode, the refresh controller increments a counter at a rate that is half the rate the counter is incremented in the full density mode. A refresh trigger pulse, which initiates the refresh of the memory cells, is generated when the counter has incremented to one of a first counter stage in the full density mode and a counter stage two stages beyond the first counter stage in the half density mode. Circuitry is also provided for ignoring some auto-refresh commands applied to the SDRAM in the half density mode so that the memory cells are also refreshed less frequently in the auto-refresh mode.

Abstract: A dual mode, full density/half density SDRAM includes a refresh controller specifically adapted to refresh memory cells of the SDRAM in the half density mode at a rate that is significantly slower than the rate at which the memory cells are refreshed in the full density mode. In the full density mode, the refresh controller increments a counter at a rate that is half the rate the counter is incremented in the full density mode. A refresh trigger pulse, which initiates the refresh of the memory cells, is generated when the counter has incremented to one of a first counter stage in the full density mode and a counter stage two stages beyond the first counter stage in the half density mode. Circuitry is also provided for ignoring some auto-refresh commands applied to the SDRAM in the half density mode so that the memory cells are also refreshed less frequently in the auto-refresh mode.

Abstract: A method of verifying whether unprogrammed antifuses are leaky in a semiconductor memory. The method involves the steps of: connecting the antifuse in series with a node; providing current to the node, the current being sufficient to charge the node from a first to a second voltage; detecting whether the voltage at the node charges to the second voltage, or remains at the first voltage to indicate that the antifuse is leaky; outputting signals indicating the result of the detection; and detecting the voltage at the node remains at the first voltage indicates that the antifuse is leaky. In another embodiment, a method of verifying whether antifuses have been programmed properly in a semiconductor memory.

Abstract: Testing a memory device having M data pads with a tester having N<M data pads, comprising writing data to the memory device in a test configuration; then in a normal configuration reading the data and writing the data back to the memory device. Subsequently the memory device is configured to a test configuration and the data is read to the tester to check for error.

Abstract: A dual mode, full density/half density SDRAM includes a refresh controller specifically adapted to refresh memory cells of the SDRAM in the half density mode at a rate that is significantly slower than the rate at which the memory cells are refreshed in the full density mode. In the full density mode, the refresh controller increments a counter at a rate that is half the rate the counter is incremented in the full density mode. A refresh trigger pulse, which initiates the refresh of the memory cells, is generated when the counter has incremented to one of a first counter stage in the full density mode and a counter stage two stages beyond the first counter stage in the half density mode. Circuitry is also provided for ignoring some auto-refresh commands applied to the SDRAM in the half density mode so that the memory cells are also refreshed less frequently in the auto-refresh mode.

Abstract: A structure and method to improve sense amplifier operation in memory circuits is provided. An illustrative method of the present invention includes taking the predecoded the row address signals (i.e. RA123<n>, LPHe<n>, LPHo<n>) that run down the rowdriver seams in a memory array (peripheral circuitry), and decoding those address signals in the sense amplifier gaps. The decoding is done to fire a signal that runs up the sense amplifier gap and biases the sense amplifier to fire in one direction or the other.

Abstract: Circuitry for programming antifuse elements is provided which permits all antifuse elements in a bank to be programmed simultaneously, thereby enhancing the speed at which antifuse elements may be programmed. In one embodiment, a feedback circuit is associated with each antifuse element to stop the flow of current through the antifuse element once it is programmed. In another embodiment, circuitry is provided for generating a separate programming pulse for each antifuse element, which is selected for programming.

Abstract: A test-mode latching circuit residing on an integrated circuit with test circuitry and operational circuitry has an enable state and a disable state. In the enable state, a test key is able to be latched so as to trigger a test mode. In the disable state, test key inputs are not latched, and thus, test modes are not entered. Initially, the circuit is readily enabled so that the IC can be tested upon fabrication. The circuit is locked in a disable state before external sale. A re-enable circuit is present to preclude inadvertent switching of the latching circuit back into the enable state during customer operation. Safeguards are implemented to avoid inadvertently re-enabling the latching circuit. To re-enable the latching circuit, an out-of-spec voltage is applied to an anti-fuse capacitor or programmable logic circuit while an out-of-spec voltage of the same or another signal is detected at a field device. In one embodiment, the state switches to the enable state in response to the out-of-spec voltage.

Abstract: A circuit for adjusting a time when data is delivered to a data terminal with respect to an external clock signal includes a data passing circuit and a delay adjusting circuit. The delay adjusting circuit accepts a plurality of control signals each arranged to control passgates arranged in columns, with one column being controlled by a respective one of the control signals. A clock signal passes in parallel manner through a variety of delay gates, and each delay gate is coupled in series with one of the passgates. By selecting a path through desired passgates, one delay path is selected and the delay time added to the clock signal. This delayed clock signal is used to control the data passing circuit, which controls when data is output to the output terminals relative to the original clock signal. The control signals are created by selectively coupling or decoupling the control signals from a static voltage, and fuses or antifuses can be used to facilitate this coupling or decoupling.

Abstract: A Dynamic Random Access Memory (DRAM) device includes a bus for distributing a boosted voltage VCCP within the device. A conventional internal voltage regulator, ring oscillator, and charge pump help to boost the boosted voltage VCCP on the bus when the voltage VCCP falls below a preset minimum. During testing of the DRAM device, when the demand on the boosted voltage VCCP can be four or more times as much as it is under normal operating conditions, an external current source drives current ICCP into an unused bond pad, such as a no-connection (NC) or address signal bond pad. An NMOS transistor switch then connects this bond pad to the boosted voltage VCCP bus when a pump circuit controlled by the ring oscillator activates the switch. As a result, the external current augments the efforts of the internal charge pump to boost the voltage VCCP during testing, so there is no need to build the internal charge pump with oversized capacitors to handle the excessive VCCP demand during testing.

Abstract: A test-mode latching circuit residing on an integrated circuit with test circuitry and operational circuitry has an enable state and a disable state. In the enable state, a test key is able to be latched so as to trigger a test mode. In the disable state, test key inputs are not latched, and thus, test modes are not entered. Initially, the circuit is readily enabled so that the IC can be tested upon fabrication. The circuit is locked in a disable state before external sale. A re-enable circuit is present to preclude inadvertent switching of the latching circuit back into the enable state during customer operation. Safeguards are implemented to avoid inadvertently re-enabling the latching circuit. To re-enable the latching circuit, an out-of-spec voltage is applied to an anti-fuse capacitor or programmable logic circuit while an out-of-spec voltage of the same or another signal is detected at a field device. In one embodiment, the state switches to the enable state in response to the out-of-spec voltage.

Abstract: A test-mode latching circuit residing on an integrated circuit with test circuitry and operational circuitry has an enable state and a disable state. In the enable state, a test key is able to be latched so as to trigger a test mode. In the disable state, test key inputs are not latched and, thus, test modes are not entered. Initially, the circuit is readily enabled so that the IC can be tested upon fabrication. The circuit is locked in a disable state before external sale. A re-enable circuit is present to preclude inadvertent switching of the latching circuit back into the enable state during customer operation. Safeguards are implemented to avoid inadvertently re-enabling the latching circuit. To re-enable the latching circuit, an out-of-spec voltage is applied to an anti-fuse capacitor or programmable logic circuit while an out-of-spec voltage of the same or another signal is detected at a field device. In one embodiment, the state switches to the enable state in response to the out-of-spec voltage.

Abstract: A dual mode, full density/half density SDRAM includes a refresh controller specifically adapted to refresh memory cells of the SDRAM in the half density mode at a rate that is significantly slower than the rate at which the memory cells are refreshed in the full density mode. In the half density mode, the refresh controller increments a counter at a rate that is half the rate the counter is incremented in the full density mode. A refresh trigger pulse, which initiates the refresh of the memory cells, is generated when the counter has incremented to one of a first counter stage in the full density mode and a counter stage two stages beyond the first counter stage in the half density mode. Circuitry is also provided for ignoring some auto-refresh commands applied to the SDRAM in the half density mode so that the memory cells are also refreshed less frequently in the auto-refresh mode.

Abstract: A dual mode, full density/half density SDRAM includes a refresh controller specifically adapted to refresh memory cells of the SDRAM in the half density mode at a rate that is significantly slower than the rate at which the memory cells are refreshed in the full density mode. In the half density mode, the refresh controller increments a counter at a rate that is half the rate the counter is incremented in the full density mode. A refresh trigger pulse, which initiates the refresh of the memory cells, is generated when the counter has incremented to one of a first counter stage in the full density mode and a counter stage two stages beyond the first counter stage in the half density mode. Circuitry is also provided for ignoring some auto-refresh commands applied to the SDRAM in the half density mode so that the memory cells are also refreshed less frequently in the auto-refresh mode.

Abstract: A test-mode latching circuit residing on an integrated circuit with test circuitry and operational circuitry has an enable state and a disable state. In the enable state, a test key is able to be latched so as to trigger a test mode. In the disable state, test key inputs are not latched, and thus, test modes are not entered. Initially, the circuit is readily enabled so that the IC can be tested upon fabrication. The circuit is locked in a disable state before external sale. A re-enable circuit is present to preclude inadvertent switching of the latching circuit back into the enable state during customer operation. Safeguards are implemented to avoid inadvertently re-enabling the latching circuit. To re-enable the latching circuit, an out-of-spec voltage is applied to an anti-fuse capacitor or programmable logic circuit while an out-of-spec voltage of the same or another signal is detected at a field device. In one embodiment, the state switches to the enable state in response to the out-of-spec voltage.

Abstract: A circuit for adjusting a time when data is delivered to a data terminal with respect to an external clock signal includes a data passing circuit and a delay adjusting circuit. The delay adjusting circuit accepts a plurality of control signals each arranged to control passgates arranged in columns, with one column being controlled by a respective one of the control signals. A clock signal passes in parallel manner through a variety of delay gates, and each delay gate is coupled in series with one of the passgates. By selecting a path through desired passgates, one delay path is selected and the delay time added to the clock signal. This delayed clock signal is used to control the data passing circuit, which controls when data is output to the output terminals relative to the original clock signal. The control signals are created by selectively coupling or decoupling the control signals from a static voltage, and fuses or antifuses can be used to facilitate this coupling or decoupling.

Abstract: A structure and method to improve sense amplifier operation in memory circuits is provided. An illustrative method of the present invention includes taking the predecoded the row address signals (i.e. RA123<n>, LPHe<n>, LPHo<n>) that run down the rowdriver seams in a memory array (peripheral circuitry), and decoding those address signals in the sense amplifier gaps. The decoding is done to fire a signal that runs up the sense amplifier gap and biases the sense amplifier to fire in one direction or the other.