REFERENCE VOLTAGE CIRCUIT

• US 20090322305A1
• Filed: 11/11/2005
• Published: 12/31/2009
• Est. Priority Date: 11/18/2004
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: De Cremoux, Guillaumc
• Granted Patent: US 8,125,209 B2
• Time in Patent Office: Days
• US Class Current: 323/313
• CPC Class Codes: G11C 27/005 with non-volatile charge storage, e.g. on floating gate or MNOS

Abstract

The present invention provides a reference voltage circuit making use of a non-volatile and non-modifiable storage of an electric charge. A tunable transformation module is adapted to transform a constant voltage corresponding to the constant stored charge into an output reference voltage. Further, a control loop provides tuning of the transformation module by means of an external calibration module with respect to a high precision reference voltage source. During a calibration procedure the transformation module is tuned in such a way that the output reference voltage equals the high precision reference voltage. After disconnecting reference voltage electronic circuit and calibration module, the output reference voltage is governed by the charge stored by means of the non-volatile storage and by the configuration of the tunable transformation module. It remains constant and accurate with respect to time and temperature and consumes only a minimum of electric current.

Claims

1. A reference voltage electronic circuit comprising:

a capacitive element having a floating gate for non-volatile and non-modifiable storage of a constant charge,

a tunable transformation module having an input being coupled to the capacitive element providing a constant voltage corresponding to the constant charge, the transformation module providing tunable transformation of the constant voltage to an output reference voltage,

a control loop for tuning the transformation module by means of an external calibration module making use of a high precision reference voltage source.

2. The reference voltage electronic circuit according to claim 1, wherein the tunable transformation module comprises an operational amplifier and at least first and second resistors forming a feedback loop, the resistance of the first and/or second resistors being tunable by means of the external calibration module.

3. The reference voltage electronic circuit according to claim 1, wherein the capacitive element comprising an erasable programmable read-only memory module.

4. The reference voltage electronic circuit according to claim 2, wherein each of the first and/or second resistors comprise a circuit of a set of resistors and a set of metal-oxide-semiconductor based switches, the resistance of the first and/or second resistor being determined by means of the configuration of the set of switches.

5. The reference voltage electronic circuit according to claim 4, wherein the resistances of the first and/or second resistors are determined by means of the calibration module and wherein the switch configuration is stored by means of a an EPROM module.

8. A battery powered portable electronic device having a voltage regulator making use of a reference voltage electronic circuit according to claim 1.

9. A cellular phone comprising a reference voltage electronic circuit according to claim 1.

6. A method of calibrating a reference voltage electronic circuit comprising the steps of:

storing a constant charge by means of a capacitive element having a floating gate for non-volatile and non-modifiable storage of charges,

providing a constant voltage corresponding to the constant charge to an input of a tunable transformation module,

transforming the constant voltage to an output reference voltage by means of the tunable transformation module,

calibrating the reference voltage electronic circuit by tuning the transformation module in response to receive a control signal from an external calibration module making use of a high precision reference voltage source.

7. A calibration module for calibrating a reference voltage electronic circuit having a capacitive element with a floating gate for non-volatile and non-modifiable storage of a constant charge and having a tunable transformation module having an input being coupled to the capacitive element providing a constant voltage corresponding to the constant charge, the calibration module comprising:

a high precision reference voltage,

a comparator module being adapted to compare the output of the reference voltage electronic circuit with the output of the high precision voltage source, the comparator module being adapted to tune the tunable transformation module of the reference voltage electronic circuit.