Programmable addressing circuitry for increasing memory yield
View Patent ↗Integrated circuits with memory elements are provided. A memory element may include a storage circuit coupled to data lines through access transistors. The access transistors may have gates that are controlled by an address signal. The address signal may be asserted during read/write operations to turn on the access transistors so that read/write data can be passed through the access transistors. The voltage level to which the address signal is raised during read/write operations may be adjusted using programmable voltage biasing circuitry. A number of integrated circuits may be tested during device characterization procedures to determine the amount by which the address signal should be adjusted using the programmable voltage biasing circuit so that the memory elements in the integrated circuits satisfy design criteria.
1. An integrated circuit comprising:
memory elements operable to receive a power supply voltage, wherein the memory elements comprise address transistors with gates operable to receive address signals; and
addressing circuitry operable to assert the address signals at a single voltage level that is less than the power supply voltage, wherein the addressing circuitry comprises a plurality of drivers operable to supply the address signals to the gates and voltage biasing circuitry operable to supply an adjustable bias voltage to the drivers.
2. The integrated circuit defined in claim 1 further comprising word lines operable to convey the address signals to the gates, wherein the addressing circuitry comprises a word line decoder operable to supply the address signals to the word lines.
3. The integrated circuit defined in claim 2 wherein the plurality of drivers is interposed between the word line decoder and the word lines.
4. The integrated circuit defined in claim 1 wherein the voltage biasing circuitry comprises programmable voltage biasing circuitry.
5. The integrated circuit defined in claim 1 wherein the voltage biasing circuitry comprises a transistor coupled between a power supply terminal and a path operable to supply the adjustable bias voltage to the drivers.
6. The integrated circuit defined in claim 5 further comprising an adjustable resistor chain coupled to the power supply terminal.
7. The integrated circuit defined in claim 1 further comprising:
a power supply terminal;
a ground terminal;
a resistor chain coupled between the power supply terminal and a ground terminal;
transistors coupled to intermediate nodes within the resistor chain; and
a plurality of logic gates operable to receive static control signals and operable to apply corresponding output signals to the transistors.
8. The integrated circuit defined in claim 7 further comprising a control path operable to apply an enable signal to the plurality of logic gates.
9. The integrated circuit defined in claim 8 wherein the voltage biasing circuitry comprises a transistor coupled between the power supply terminal and a path operable to supply the adjustable bias voltage to the drivers, the integrated circuit further comprising circuitry operable to receive the static control signals and operable to supply a corresponding control signal to the transistor.
10. The integrated circuit defined in claim 9 wherein the circuitry comprises a logic gate operable to receive the static control signals from a plurality of corresponding signal paths, wherein the logic gate has an output operable to supply the corresponding control signal and wherein the transistor has a gate coupled to the output.
11. A method for operating an integrated circuit having at least one memory element, wherein the integrated circuit is supplied with a power supply voltage, the method comprising:
with the at least one memory element, receiving only an asserted address signal at a single voltage level that is less than the power supply voltage during write operations; and
with addressing circuitry, supplying the asserted address signal at the single voltage level and receiving an address signal magnitude setting determined based on test data gathered from a plurality of integrated circuits.
12. The method defined in claim 11 further comprising:
with the at least one memory element, receiving only the asserted address signal at the single voltage level that is less than the power supply voltage during read operations.
13. A method for operating an integrated circuit, comprising:
receiving a power supply voltage with a memory element;
providing an asserted address signal to the memory element with control circuitry, wherein the asserted address signal has a voltage level that is different than the power supply voltage during read and write operations; and
with a driver circuit in the control circuitry that outputs the asserted address signal, receiving an adjustable power supply voltage.
14. The method defined in claim 13 , wherein the voltage level of the asserted address signal is less than the power supply voltage during the read and write operations.
15. The method defined in claim 13 , further comprising:
with the control circuitry, receiving an address signal magnitude setting determined based on test data gathered from a plurality of integrated circuits, wherein the control circuitry generates address signals having a magnitude that is established by the address signal magnitude setting.
16. The method defined in claim 13 ,
wherein the adjustable power supply voltage remains fixed at a predetermined voltage level during normal operation of the integrated circuit.