Auto-corrected IO driver architecture

1. A circuit, comprising:

a first driver including a first transistor bank connected between a first predetermined voltage and an output pad, the first transistor bank including a first driver transistor, a first primary calibration transistor, and a plurality of first secondary calibration transistors,

wherein a data signal controls the first driver transistor, and

wherein a most significant bit of a first calibration code controls the first primary calibration transistor, the first calibration code having a plurality of bits consisting of K most significant bits and L least significant bits,

wherein an output of at least one first logic gate controls the plurality of first secondary calibration transistors, a respective first logic gate receiving the most significant bit of the first calibration code and at least one of the least significant bits of the first calibration code, and

wherein K and L are positive integers.

2. The circuit according to claim 1 , wherein the K most significant bits of the first calibration code are a thermometric code and the L least significant bits of the first calibration code are a binary code.

3. The circuit according to claim 1 , wherein K is one.

4. The circuit according to claim 3 , wherein the at least one first logic gate includes:

an AND gate configured to receive the most significant bit of the first calibration code at a first input and the L least significant bits of the first calibration code respectively at L second inputs, and to output a first control code to a first subset of the plurality of first secondary calibration transistors; and

an OR gate configured to receive the most significant bit of the first calibration code at a first input and the L least significant bits of the first calibration code respectively at L second inputs, and to output a second control code to a second subset of the plurality of first secondary calibration transistors.

5. The circuit according to claim 1 , further comprising:

a second driver including a second transistor bank and a second resistor connected in series between a second predetermined voltage and the output pad, the second transistor bank including a second driver transistor, a second primary calibration transistor and a plurality of second secondary calibration transistors,

wherein the second primary calibration transistor and the plurality of second secondary calibration transistors are respectively controlled based on a second calibration code having K most significant bits and L least significant bits and on an output of at least one second logic gate.

6. The circuit according to claim 5 , wherein the plurality of first secondary calibration transistors have a first conductivity type and the plurality of second secondary calibration transistors have a second conductivity type opposite the first conductivity type.

7. The circuit according to claim 5 , wherein the second calibration code is an inversion of the first calibration code.

8. A system, comprising:

a memory array; and

an IO driver circuit configured to output a signal to the memory array, the IO driver circuit including:

a first driver including a first transistor bank and a first resistor connected in series between a first predetermined voltage and an output pad, the first transistor bank including a first driver transistor and a plurality of first calibration transistors, the plurality of first calibration transistors including a main calibration transistor,

a second driver including a second transistor bank and a second resistor connected in series between a second predetermined voltage and the output pad, the second transistor bank including a second driver transistor and a plurality of second calibration transistors,

a data signal source configured to control the first driver transistor with a data signal,

a calibration signal source configured to control the main calibration transistor with a most significant bit of a first calibration code, the first calibration code consisting of K most significant bits and L least significant bits, and

a logic gate configured to vary an impedance of the first driver based on bits of the first calibration code, and to vary an impedance of the second driver based on bits of a second calibration code.

9. The system according to claim 8 , wherein the K most significant bits of the first calibration code are a thermometric code and the L least significant bits of the first calibration code are a binary code, where K and L are positive integers.

10. The system according to claim 9 , wherein K is one.

11. The system according to claim 10 , wherein the logic gate is part of a logic circuit that is configured to:

vary an impedance of a first subset of the plurality of first calibration transistors based on at least one AND operation respectively between the most significant bit of the first calibration code and the L least significant bits of the first calibration code, and

vary an impedance of a second subset of the plurality of first calibration transistors based on at least one OR operation respectively between the most significant bit of the first calibration code and the L least significant bits of the first calibration code,

wherein the first subset and the second subset do not include the main calibration transistor.

12. The system according to claim 8 , wherein the plurality of first calibration transistors is a plurality of p-type transistors and the plurality of second calibration transistors is a plurality of n-type transistors.

13. The system according to claim 8 , further comprising an inverter configured to receive the first calibration code and generate the second calibration code.

14. A method, comprising:

selectively providing, by a pull-up driver, a path between a first predetermined voltage and an output pad by controlling a first transistor bank and a first resistor connected in series therebetween, the first transistor bank including a first driver transistor, a first calibration transistor, and a plurality of second calibration transistors;

selectively providing, by a pull-down driver, a path between a second predetermined voltage and the output pad by controlling a second transistor bank and a second resistor connected in series therebetween, the second transistor bank including a second driver transistor and a plurality of third calibration transistors;

controlling the first driver transistor by a data signal;

controlling the first calibration transistor by a most significant bit of a first calibration code;

controlling the plurality of second calibration transistors by a logical combination of the K most significant bits of the first calibration code and the L least significant bits of the first calibration code, K and L being positive integers; and

controlling the plurality of third calibration transistors by a logical combination of the K most significant bits of a second calibration code and the L least significant bits of the second calibration code,

wherein the first calibration code consists of the K most significant bits of the first calibration code and the L least significant bits of the second calibration code.

15. The method according to claim 14 , wherein the K most significant bits of the calibration code are a thermometric code and the L least significant bits of the calibration code are a binary code.

16. The method according to claim 14 , wherein K is one.

17. The method according to claim 16 , further comprising:

performing a plurality of AND operations respectively between the most significant bit of the first calibration code and the L least significant bits of the first calibration code so as to generate a first control code; and

performing a plurality of OR operations respectively between the most significant bit of the first calibration code and the L least significant bits of the first calibration code so as to generate a second control code.

18. The method according to claim 17 , further comprising:

outputting the first control code to a first subset of the plurality of second calibration transistors; and

outputting the second control code to a second subset of the plurality of second calibration transistors.

19. The method according to claim 17 , further comprising:

performing a plurality of AND operations respectively between the most significant bit of the second calibration code and the L least significant bits of the second calibration code so as to generate a third control code;

performing a plurality of OR operations respectively between the most significant bit of the second calibration code and the L least significant bits of the second calibration code so as to generate a fourth control code;

outputting the third control code to a first subset of the plurality of third calibration transistors; and

outputting the fourth control code to a second subset of the plurality of third calibration transistors.

20. The method according to claim 14 , further comprising inverting the first calibration code to obtain the second calibration code.