Floating-gate reference circuit

A system comprising:

• a flash analog-to-digital converter containing a plurality of voltage comparators;
• a switch operative to provide a program-mode of operation and a run-mode of operation;
• a first floating-gate field effect transistor connected to a first voltage comparator in the plurality of voltage comparators, the first floating-gate field effect transistor being programmable to store a first floating-gate charge when the switch is operative in the program-mode of operation, and to produce, when the switch is operative in the run-mode of operation, a first reference voltage output that is proportional to the first floating-gate charge;
• a second floating-gate field effect transistor connected to a second voltage comparator in the plurality of voltage comparators, the second floating-gate field effect transistor being programmable to store a second floating-gate charge and produce a second reference voltage that is proportional to the second floating-gate charge;
• and
• a third floating-gate field effect transistor connected to a third voltage comparator in the plurality of voltage comparators, the third floating-gate field effect transistor being programmable to store a third floating-gate charge and produce a third reference voltage output that is proportional to the third floating-gate charge,
• wherein the first voltage reference output, the second voltage reference output, and the third voltage reference output provide a logarithmic change in voltage reference amplitudes for a flash analog-to-digital conversion in the flash analog-to-digital converter.

A method of providing a reference, the method comprising:

• providing a floating-gate field effect transistor;
• providing a switch;
• setting the switch in a first position to program a charge into the floating-gate field effect transistor, wherein programming the charge into the floating-gate field effect transistor includes:
• connecting a gate terminal of the floating-gate field effect transistor to a first input terminal of a voltage buffer;
• connecting an input voltage signal to a second input terminal of the voltage buffer;
• providing a feedback capacitor that capacitively couples an output voltage of the voltage buffer to the gate terminal of the floating-gate field effect transistor;
• selectively providing one of a hot-electron charge injection process and a tunneling process to the floating-gate field effect transistor to adjust the amplitude of charge stored in the floating-gate field effect transistor to a desired amplitude;
• and
• measuring the output voltage of the voltage buffer to determine the amplitude of charge stored in the floating-gate field effect transistor;
• and
• setting the switch in a second position to use the floating-gate field effect transistor as at least one of a voltage reference or a current reference.

A method of providing a reference, the method comprising:

• providing a floating-gate field effect transistor;
• connecting a drain terminal of the floating-gate field effect transistor to a first supply voltage;
• connecting a source terminal of the floating-gate field effect transistor to an injection voltage source;
• selectively providing one of a hot-electron charge injection process and a tunneling process to the floating-gate field effect transistor to adjust the amplitude of charge stored in the floating-gate field effect transistor to a desired amplitude;
• disconnecting the source terminal of the floating-gate field effect transistor from the injection voltage source;
• connecting the source terminal of the floating-gate field effect transistor to the first supply voltage;
• and
• using the floating-gate field effect transistor as a reference voltage node.

A method of providing a reference, the method comprising:

• providing a floating-gate field effect transistor;
• connecting a drain terminal of the floating-gate field effect transistor to a first supply voltage;
• connecting a source terminal of the floating-gate field effect transistor to an injection voltage source;
• selectively providing one of a hot-electron charge injection process and a tunneling process to the floating-gate field effect transistor to adjust the amplitude of charge stored in the floating-gate field effect transistor to a desired amplitude;
• disconnecting the source terminal of the floating-gate field effect transistor from the injection voltage source;
• connecting the source terminal of the floating-gate field effect transistor to a second supply voltage;
• and
• using the floating-gate field effect transistor as a reference current source.

A method of providing a reference, the method comprising:

• providing a floating-gate field effect transistor;
• connecting a source terminal of the floating-gate field effect transistor to a first supply voltage;
• connecting a drain terminal of the floating-gate field effect transistor to an injection voltage source;
• selectively providing one of a hot-electron charge injection process and a tunneling process to the floating-gate field effect transistor to adjust the amplitude of charge stored in the floating-gate field effect transistor to a desired amplitude;
• disconnecting the drain terminal of the floating-gate field effect transistor from the injection voltage source;
• connecting the drain terminal of the floating-gate field effect transistor to the first supply voltage;
• and
• using the floating-gate field effect transistor as a reference voltage node.

A method of providing a reference, the method comprising:

• providing a floating-gate field effect transistor;
• connecting a source terminal of the floating-gate field effect transistor to a first supply voltage;
• connecting a drain terminal of the floating-gate field effect transistor to an injection voltage source;
• selectively providing one of a hot-electron charge injection process and a tunneling process to the floating-gate field effect transistor to adjust the amplitude of charge stored in the floating-gate field effect transistor to a desired amplitude;
• disconnecting the drain terminal of the floating-gate field effect transistor from the injection voltage source;
• connecting the drain terminal of the floating-gate field effect transistor to a second supply voltage;
• and
• using the floating-gate field effect transistor as a reference current source.

A method of providing a reference, the method comprising:

• setting a switch in a first position to program a charge into a floating-gate field effect transistor;
• connecting a gate terminal of the floating-gate field effect transistor to a first input terminal of a voltage buffer;
• connecting an input voltage signal to a second input terminal of the voltage buffer;
• and
• providing a feedback capacitor that capacitively couples an output voltage of the voltage buffer to the gate terminal of the floating-gate field effect transistor.

A system comprising:

• a floating-gate charge programmer;
• a switch operative to provide a program-mode of operation and a run-mode of operation;
• a digital-to-analog converter including:
• a first floating-gate field effect transistor that is programmable by the floating-gate charge programmer to store a first floating-gate charge when the switch is operative in the program-mode of operation, and to produce, when the switch is operative in the run-mode of operation, at least one of a first reference voltage or a first reference current proportional to the first floating-gate charge;
• and
• a second floating-gate field effect transistor that is programmable by the floating-gate charge programmer to store a second floating-gate charge when the switch is operative in the program-mode of operation, and to produce, when the switch is operative in the run-mode of operation, at least one of a second reference voltage or a second reference current proportional to the second floating-gate charge.

A system comprising:

• a floating-gate charge programmer;
• a switch operative to provide a program-mode of operation and a run-mode of operation;
• and
• a first floating-gate field effect transistor that is programmable by the floating-gate charge programmer to store a first floating-gate charge when the switch is operative in the program-mode of operation, and to produce, when the switch is operative in the run-mode of operation, at least one of a first reference voltage or a first reference current proportional to the first floating-gate charge;
• and
• a second floating-gate field effect transistor that is connected to the first floating-gate field effect transistor to form a current-mirror circuit wherein the source-drain current of the second floating-gate field effect transistor is proportional to the source-drain current of the first floating-gate field effect transistor.

A system comprising:

• a floating-gate charge programmer;
• a switch operative to provide a program-mode of operation and a run-mode of operation;
• a first floating-gate field effect transistor that is programmable by the floating-gate charge programmer to store a first floating-gate charge when the switch is operative in the program-mode of operation, and to produce, when the switch is operative in the run-mode of operation, at least one of a first reference voltage and a first reference current proportional to the first floating-gate charge;
• and
• a second floating-gate field effect transistor that is connected to the first floating-gate field effect transistor to form a current-summing circuit wherein the output current of the current-summing circuit is proportional to the sum of the source-drain currents of the first and the second floating-gate field effect transistors.