WO2006069157A2 - Temperature-stable voltage reference circuit - Google Patents

Temperature-stable voltage reference circuit Download PDF

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Publication number
WO2006069157A2
WO2006069157A2 PCT/US2005/046381 US2005046381W WO2006069157A2 WO 2006069157 A2 WO2006069157 A2 WO 2006069157A2 US 2005046381 W US2005046381 W US 2005046381W WO 2006069157 A2 WO2006069157 A2 WO 2006069157A2
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WO
WIPO (PCT)
Prior art keywords
voltage
bias generator
coupled
circuit
diode
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US2005/046381
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French (fr)
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WO2006069157A3 (en
Inventor
Brian J. Cherek
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Atmel Corp
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Atmel Corp
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Publication date
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Publication of WO2006069157A3 publication Critical patent/WO2006069157A3/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F3/00—Non-retroactive systems for regulating electric variables by using an uncontrolled element, or an uncontrolled combination of elements, such element or such combination having self-regulating properties
    • G05F3/02—Regulating voltage or current
    • G05F3/08—Regulating voltage or current wherein the variable is DC
    • G05F3/10—Regulating voltage or current wherein the variable is DC using uncontrolled devices with non-linear characteristics
    • G05F3/16—Regulating voltage or current wherein the variable is DC using uncontrolled devices with non-linear characteristics being semiconductor devices
    • G05F3/20—Regulating voltage or current wherein the variable is DC using uncontrolled devices with non-linear characteristics being semiconductor devices using diode- transistor combinations
    • G05F3/30—Regulators using the difference between the base-emitter voltages of two bipolar transistors operating at different current densities

Definitions

  • the present invention relates generally to integrated circuits and more particularly to circuits for producing reference voltages and reference currents.
  • Temperature-stable voltage references have a multiplicity of applications. Examples of usage could be voltage monitoring circuits, temperature sensing devices, data conversion products (ADCs and DACs), and frequency/time measurement devices. It is very important for certain low voltage applications that require temperature stable devices to operate increasingly at lower voltages. For example, there are many products in the consumer marketplace in which low voltage/low power operation is needed, such as in cell phones, hearing aids, MP3 players, etc.
  • a voltage reference circuit comprises a PTAT bias generator circuit and a band gap voltage system coupled to the PTAT bias generator circuit.
  • the band gap voltage system includes at least one diode-connected CMOS transistor.
  • CMOS device allows for a lower output voltage level than a bipolar device, particularly at colder temperatures. This allows for lower overall operating voltage for the device.
  • the present invention provides for the creation of a temperature-stable reference voltage at a supply voltage and/or operating temperature lower than conventional circuits.
  • Figure IA illustrates a first embodiment of a conventional bandgap reference circuit for providing a temperature-stable voltage.
  • Figure IB illustrates a second embodiment of a conventional bandgap circuit.
  • Figure 2A illustrates a general embodiment of a temperature stable voltage reference circuit in accordance with the present invention.
  • FIG. 2B illustrates a specific embodiment of a temperature stable voltage reference circuit in accordance with the present invention.
  • the present invention relates generally to integrated circuits and more particularly to circuits for producing reference voltages and reference currents.
  • the following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements.
  • Various modifications to the preferred embodiments and the generic principles and features described herein will be readily apparent to those skilled in the art.
  • the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features described herein.
  • FIG. IA illustrates a first embodiment of a conventional bandgap reference circuit 10 for providing a temperature-stable voltage.
  • the conventional bandgap reference circuit 10 delivers a voltage of approximately 1.2 V. This is achieved by two vertical PNP transistors 12 and 14 as shown in Fig. IA with an emitter area ratio of n and equal emitter currents. The difference between their base emitter voltages is in this case proportional to the absolute temperature (PTAT).
  • An operational amplifier 22 controls the emitter currents in such a way that the difference in base-emitter voltages is put across resistor R' PTAT 16. This means that the current through the resistor 16 is also PTAT and so is the current through all transistors in Fig. IA.
  • the voltage across R'i 26 is then also PTAT.
  • the bandgap referred voltage V' BG is formed by adding a base- emitter voltage, which has a negative temperature coefficient, to a voltage across R'i, 26 which has a positive temperature coefficient.
  • FIG. IB A second embodiment of a conventional bandgap circuit 10' is shown in Figure IB. Connecting a resistor R 2 50 across the bandgap reference transistor 28' leads to
  • the absolute V EB of the bipolar device 28' limits the minimum possible output voltage of the circuit, as well as the minimum operating VDD. This is particularly true at colder temperatures, where the absolute V EB of device 28' increases.
  • a temperature-stable voltage reference in accordance with the present invention is disclosed that allows for an output voltage lower than the standard 1.2 volt, allowing for low-voltage operation.
  • the key characteristic of this cell is substitution of a diode-connected bipolar bandgap reference transistor with a diode-connected CMOS bandgap reference transistor.
  • a diode-connected CMOS transistor allows for a voltage with a negative temperature coefficient.
  • the absolute output voltage and absolute operating VDD can both be reduced, because the CMOS V T can be made lower than the bipolar V EB at a given operating current.
  • FIG. 2A illustrates a general embodiment of temperature voltage reference circuit 100 in accordance with the present invention.
  • a PTAT bias generator 102 provides a I PTA T to the output.
  • the key feature of the circuit 100 is that a diode connected CMOS transistor 160 is the bandgap reference transistor rather than the bipolar bandgap reference transistor 28.
  • FIG. 2B illustrates a more specific embodiment of the circuit 100 in accordance with the present invention.
  • the PTAT bias generator system comprises a first NMOS device, a second NMOS device, ratioed in size to the first, a first resistor, coupled to the second NMOS device, and two PMOS devices, coupled to the first and second NMOS devices, forming a bias generator loop in conjunction with the aforementioned devices.
  • a third PMOS device coupled to the other two PMOS devices, and ratioed in size to those other devices, to provides a PTAT output current of the bias generator.
  • the advantage of a circuit in accordance with the present invention is that the diode-connected CMOS device allows for a lower output voltage level than a bipolar device, particularly at colder temperatures. This allows for lower overall operating voltage for the device.
  • the present invention provides for the creation of a temperature-stable reference voltage at a supply voltage and/or operating temperature lower than conventional circuits.
  • the present invention can be provided in a conventional CMOS process.
  • Performance would be determined by specific process parameters, particularly threshold voltage and device mobility.
  • the bandgap transistor is an NMOS device, it could be replaced with a PMOS device, any and all of the transistors within the circuit could be NMOS devices and they would be within the spirit and scope of the present invention. Accordingly, many modifications may be made by one of ordinary skill in the art without departing from the spirit and scope of the appended claims.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Physics & Mathematics (AREA)
  • Power Engineering (AREA)
  • Nonlinear Science (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Automation & Control Theory (AREA)
  • Control Of Electrical Variables (AREA)

Abstract

A voltage reference circuit is disclosed. The circuit comprises a PTAT bias generator circuit and a band gap transistor voltage system coupled to the operational amplifier system. The band gap voltage system includes at least one diode-connected CMOS transistor. The advantage of this configuration is that the diode-connected CMOS device allows for a lower output voltage level than a bipolar device, particularly at colder temperatures. This allows for lower overall operating voltage for the device. The present invention provides for the creation of a temperature-stable reference voltage at a supply voltage and/or operating temperature lower than conventional circuits.

Description

TEMPERATURE-STABLE VOLTAGE REFERENCE CIRCUIT
FIELD OF THE INVENTION
The present invention relates generally to integrated circuits and more particularly to circuits for producing reference voltages and reference currents.
BACKGROUND OF THE INVENTION .
It is important to provide a temperature stable voltage for a variety of applications. Temperature-stable voltage references have a multiplicity of applications. Examples of usage could be voltage monitoring circuits, temperature sensing devices, data conversion products (ADCs and DACs), and frequency/time measurement devices. It is very important for certain low voltage applications that require temperature stable devices to operate increasingly at lower voltages. For example, there are many products in the consumer marketplace in which low voltage/low power operation is needed, such as in cell phones, hearing aids, MP3 players, etc.
Accordingly, what is needed is a system and method for providing a stable reference voltage circuit that operates at lower voltages that addresses these issues. The present invention addresses such a need.
SUMMARY OF THE INVENTION
A voltage reference circuit is disclosed. The voltage reference circuit comprises a PTAT bias generator circuit and a band gap voltage system coupled to the PTAT bias generator circuit. The band gap voltage system includes at least one diode-connected CMOS transistor.
The advantage of this configuration is that the diode-connected CMOS device allows for a lower output voltage level than a bipolar device, particularly at colder temperatures. This allows for lower overall operating voltage for the device.
The present invention provides for the creation of a temperature-stable reference voltage at a supply voltage and/or operating temperature lower than conventional circuits.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure IA illustrates a first embodiment of a conventional bandgap reference circuit for providing a temperature-stable voltage. Figure IB illustrates a second embodiment of a conventional bandgap circuit. Figure 2A illustrates a general embodiment of a temperature stable voltage reference circuit in accordance with the present invention.
Figure 2B illustrates a specific embodiment of a temperature stable voltage reference circuit in accordance with the present invention.
DETAILED DESCRIPTION
The present invention relates generally to integrated circuits and more particularly to circuits for producing reference voltages and reference currents. The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the preferred embodiments and the generic principles and features described herein will be readily apparent to those skilled in the art. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features described herein.
Figure IA illustrates a first embodiment of a conventional bandgap reference circuit 10 for providing a temperature-stable voltage. The conventional bandgap reference circuit 10 delivers a voltage of approximately 1.2 V. This is achieved by two vertical PNP transistors 12 and 14 as shown in Fig. IA with an emitter area ratio of n and equal emitter currents. The difference between their base emitter voltages is in this case proportional to the absolute temperature (PTAT). An operational amplifier 22 controls the emitter currents in such a way that the difference in base-emitter voltages is put across resistor R'PTAT 16. This means that the current through the resistor 16 is also PTAT and so is the current through all transistors in Fig. IA. The voltage across R'i 26 is then also PTAT. The bandgap referred voltage V'BG is formed by adding a base- emitter voltage, which has a negative temperature coefficient, to a voltage across R'i, 26 which has a positive temperature coefficient.
If this V'BG equals the bandgap voltage of silicon (1.2V), a zero temperature coefficient results.
It is clear, however that with a worst-case supply voltage of 0.9 V, a reference voltage of 1.2V cannot be realized.
A second embodiment of a conventional bandgap circuit 10' is shown in Figure IB. Connecting a resistor R2 50 across the bandgap reference transistor 28' leads to
D
BG = "7Ϊ ^T V EB + * PTAT ^X J K\ + K2
The result is a simple resistive division of the conventional bandgap reference voltage of 1.2V. By taking the temperature dependence of the integrated resistors into account, a zero temperature coefficient can be realized.
However, even in this circuit of Figure IB, the absolute VEB of the bipolar device 28' limits the minimum possible output voltage of the circuit, as well as the minimum operating VDD. This is particularly true at colder temperatures, where the absolute VEB of device 28' increases. A temperature-stable voltage reference in accordance with the present invention is disclosed that allows for an output voltage lower than the standard 1.2 volt, allowing for low-voltage operation.
The key characteristic of this cell is substitution of a diode-connected bipolar bandgap reference transistor with a diode-connected CMOS bandgap reference transistor. A diode-connected CMOS transistor allows for a voltage with a negative temperature coefficient. However, by using the CMOS transistor, the absolute output voltage and absolute operating VDD can both be reduced, because the CMOS VT can be made lower than the bipolar VEB at a given operating current.
Figure 2A illustrates a general embodiment of temperature voltage reference circuit 100 in accordance with the present invention. In this embodiment, a PTAT bias generator 102 provides a IPTAT to the output. The key feature of the circuit 100 is that a diode connected CMOS transistor 160 is the bandgap reference transistor rather than the bipolar bandgap reference transistor 28.
Figure 2B illustrates a more specific embodiment of the circuit 100 in accordance with the present invention. The PTAT bias generator system comprises a first NMOS device, a second NMOS device, ratioed in size to the first, a first resistor, coupled to the second NMOS device, and two PMOS devices, coupled to the first and second NMOS devices, forming a bias generator loop in conjunction with the aforementioned devices. A third PMOS device, coupled to the other two PMOS devices, and ratioed in size to those other devices, to provides a PTAT output current of the bias generator.
The advantage of a circuit in accordance with the present invention is that the diode-connected CMOS device allows for a lower output voltage level than a bipolar device, particularly at colder temperatures. This allows for lower overall operating voltage for the device.
The present invention provides for the creation of a temperature-stable reference voltage at a supply voltage and/or operating temperature lower than conventional circuits. The present invention can be provided in a conventional CMOS process.
Performance would be determined by specific process parameters, particularly threshold voltage and device mobility.
Although the present invention has been described in accordance with the embodiments shown, one of ordinary skill in the art will readily recognize that there could be variations to the embodiments and those variations would be within the spirit and scope of the present invention. For example, although in this embodiment, the bandgap transistor is an NMOS device, it could be replaced with a PMOS device, any and all of the transistors within the circuit could be NMOS devices and they would be within the spirit and scope of the present invention. Accordingly, many modifications may be made by one of ordinary skill in the art without departing from the spirit and scope of the appended claims.

Claims

CLAIMS What is claimed is:
1. A voltage reference circuit comprising: a PTAT bias generator circuit; and a band gap voltage system coupled to the PTAT bias generator circuit; wherein the band gap voltage system includes at least one diode-connected CMOS transistor.
2. The voltage reference circuit of claim 1 wherein the PTAT bias generator system comprises: a first NMOS device; a second NMOS device, ratioed in size to the first NMOS device; a first resistor, coupled to the second NMOS device; two PMOS devices, coupled to the first and second NMOS devices, to form a bias generator loop; and a third PMOS device, coupled to the two PMOS devices, and ratioed in size to those the two PMOS devices, to provide a PTAT output current of the bias generator.
3. The voltage reference circuit of claim 1 wherein a second resistor is coupled to the PTAT bias generator and the diode-connected CMOS transistor.
4. The voltage reference circuit of claim 3 wherein the band gap voltage system includes a third resistor coupled in parallel with the second resistor and the diode- connected CMOS transistor.
5. A voltage reference circuit comprising: a PTAT bias generator circuit; a band gap voltage system coupled to the PTAT bias generator circuit; wherein the band gap voltage system includes at least one diode-connected CMOS transistor; wherein the PTAT bias generator system comprises a first NMOS device; a second NMOS device, ratioed in size to the first NMOS device; a first resistor, coupled to the second NMOS device; two PMOS devices, coupled to the first and second NMOS devices, to form a bias generator loop; and a third PMOS device, coupled to the two PMOS devices, and ratioed in size to those the two PMOS devices, to provide a PTAT output current of the bias generator; wherein a second resistor is coupled to the PTAT bias generator and the diode- connected CMOS transistor; wherein the band gap voltage system includes a third resistor coupled in parallel with the second resistor and the diode-connected CMOS transistor.
PCT/US2005/046381 2004-12-22 2005-12-19 Temperature-stable voltage reference circuit Ceased WO2006069157A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US11/021,346 US20060132223A1 (en) 2004-12-22 2004-12-22 Temperature-stable voltage reference circuit
US11/021,346 2004-12-22

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WO2006069157A2 true WO2006069157A2 (en) 2006-06-29
WO2006069157A3 WO2006069157A3 (en) 2006-10-05

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CN106055011B (en) * 2016-06-23 2017-06-23 电子科技大学 A kind of self-starting power supply circuit
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CN111966159B (en) * 2020-08-29 2024-12-03 深圳市爱协生科技股份有限公司 A low voltage, low power consumption reference circuit and calibration method thereof
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Also Published As

Publication number Publication date
TWI313798B (en) 2009-08-21
WO2006069157A3 (en) 2006-10-05
TW200632613A (en) 2006-09-16
US20060132223A1 (en) 2006-06-22

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