Showing papers on "Bandgap voltage reference published in 2001"

Mutual compensation of mobility and threshold voltage temperature effects with applications in CMOS circuits

Abstract: Mutual compensation of mobility and threshold voltage temperature variations may result in a zero temperature coefficient bias point of a MOS transistor. The conditions under which this effect occurs, and stability of this bias point are investigated. Possible applications of this effect include voltage reference circuits and temperature sensors with linear dependence of voltage versus temperature. The theory is verified experimentally investigating the temperature behavior of a simple voltage reference circuit realized in 0.35 /spl mu/m CMOS process.

Curvature-compensated BiCMOS bandgap with 1-V supply voltage

Abstract: We present a bandgap circuit capable of generating a reference voltage of 0.53 V. The circuit, implemented In a submicron BiCMOS technology, operates with a supply voltage of 1 V, consuming 92 /spl mu/W at room temperature. In the bandgap circuit proposed, we use a nonconventional operational amplifier which achieves virtually zero systematic offset, operating directly from the 1-V power supply. The bandgap architecture used allows a straightforward implementation of the curvature compensation method. The proposed circuit achieves 7.5 ppm/K of temperature coefficient and 212 ppm/V of supply voltage dependence, without requiring additional operational amplifiers or complex circuits for the curvature compensation.

Voltage References: From Diodes to Precision High-Order Bandgap Circuits

Abstract: Preface. Acknowledgments. List of Tables. List of Figures. Summary. 1. The Basics. 1.1 The Diode. 1.2 Current Mirrors. Appendix A.1: Temperature Dependence of the Diode Voltage. 2. Current References. 2.1 PTAT Current References. 2.2 Startup Circuits and Frequency Compensation. 2.3 CTAT Current References. 2.4 Temperature-Independent Current References. 2.5 PTAT[superscript 2] Current Generators. 3. Voltage References. 3.1 Zero-Order References. 3.2 First-Order References. 3.3 Second-Order References (Curvature Correction). 3.4 State-of-the-Art Curvature-Correction Techniques. 4. Designing Precision Reference Circuits. 4.1 Error Sources. 4.2 The Output Stage. 4.3 Designing for Power Supply Rejection and Line Regulation. Appendix A.4: Error Sources in a Typical First-Order Bandgap. Appendix B.4: Effect of the Resistors' Temperature Coefficient on a Reference with a Current-Mode Output Stage. 5. Considering the System and the Working Environment. 5.1 Design of the Trim Network. 5.2 Package-Shift Effects. 5.3 System-Related Issues. 5.4 Characterization. Appendix A.5: Bandgap Trimming Procedure for a Mixed-Mode (Both Voltage-Mode and Current-Mode) Output Stage. Appendix B.5: Package Shift-Effects in Bandgap Reference Circuits. Appendix C.5: Derivation of the Time Required for a Reference Circuit to Change a Finite Amount upon a single-Step Stimulus. Index. About the Author.

Trimmable bandgap voltage reference

Abstract: A trimmable bandgap voltage reference circuit includes variable current sources to drive variable currents through parallel combination circuits. The parallel combination circuits include variable resistors and diodes of differing sizes. Voltages developed across the parallel combination circuits are input to a differential amplifier that is used as a feedback amplifier to bias the variable current sources. The variable current sources and variable resistors can all be digitally controlled. A processor can query the operating point of the bandgap voltage reference circuit, and can also set the current and resistance values through a control circuit.

Low voltage band gap circuit and method

Abstract: A band gap circuit that may be implemented in a standard CMOS process including a pair of parasitic vertical PNP transistors operating at a different current density. The PNP transistors have common collectors and common bases and produce a difference in base-emitter voltages which is developed across a resistor so as to produce a current having a positive temperature coefficient. The current is used to produce a positive temperature coefficient voltage which is combined with another voltage having a negative temperature coefficient to produce a band gap reference voltage. A bias voltage is applied between the base and collector of each of the PNP transistors, typically on the order of 500 millivolts. This causes the emitters of the PNP transistors to be at a voltage which can be sensed by an error amplifier implemented with standard N type MOS input transistors while maintaining a capability of operating using a relatively low power supply voltage.

Threshold voltage compensation circuits for low voltage and low power CMOS integrated circuits

Abstract: A compensation circuit for transistor threshold voltages in integrated circuits is described. The compensation circuit includes a transistor, current source, and gate reference voltage supply. The transistor is biased to provide a well bias voltage, or backgate voltage VBG, which is coupled to transistors provided on a common integrated circuit. This compensation circuit eliminates the need for gate biasing capacitors, and provides flexibility in setting threshold voltages in low voltage circuits. The gate reference voltage and current source are established to provide a desired backgate voltage VBG. Compensation circuits are described for both n-channel and p-channel transistors. A memory device is described which includes compensation circuits for controlling threshold voltages of transistors provided therein.

Low voltage bandgap reference circuit

Abstract: A bandgap reference circuit that uses reduced substrate area while requiring relatively low voltage. The circuit may include a bipolar transistor with a resistor electrically connected across the emitter-base of the bipolar transistor. The resistor sums a first current with a second current and also generates a fractional VEB. The bandgap reference circuit may have a first current proportional to VEB, and a second current proportional to a PTAT current. An impedance booster may be incorporated into the circuit. Also disclosed is a method of regulating a voltage level using embodiments of the bandgap reference circuit.

Low voltage bandgap reference circuit

Abstract: A bandgap reference circuit that operates with a voltage supply that can be lass than 1 volt and that has one stable, non-zero current operating point. The core has a current generator embedded within it and includes one operational amplifier that provides a self-regulated voltage for several transistors used in the circuit

Current bandgap voltage reference circuits and related methods

Abstract: A bandgap voltage reference circuit and related method characterized in having a first current source for generating a first current having a positive temperature coefficient, a second current source for generating a second current having a negative temperature coefficient, and a resistive element to receive both the first and second current to develop a reference voltage. By configuring the circuit such that the magnitudes of the positive and negative temperature coefficients are substantially the same, the reference voltage becomes substantially invariant with changes in temperature. Another circuit is provided in conjunction with the voltage reference circuit to substantially equalize the drain-to-source voltage of the transistors used in the voltage reference circuit.

A 1.8-V /spl Delta//spl Sigma/ modulator interface for an electret microphone with on-chip reference

Abstract: The design of a delta-sigma (/spl Delta//spl Sigma/) analog-to-digital converter (ADC) for direct voltage readout of an electret microphone is presented. The ADC is integrated on the same chip with a bandgap voltage reference and is designed to be packaged together with an electret microphone. Having a power consumption of 1.7 mW from a supply voltage of 1.8 V, the circuit is well suited for use in mobile applications. The single-loop, single-bit, fourth-order /spl Delta//spl Sigma/ ADC operates at 64 times oversampling for a signal bandwidth of 11 kHz. The measured dynamic range is 80 dB and the peak signal-to-(noise+distortion) ratio is 62 dB. The harmonic distortion is minimized by using an integrator with an instrumentation amplifier-like input which directly integrates the 125-mV peak single-ended voltage generated by the microphone. A combined continuous-time/switched-capacitor design is used to minimize power consumption.

A 1.8 V ΔΣ modulator interface for electret microphone with on-chip reference

Abstract: The design of a delta-sigma ( ) analog-to-digital converter (ADC) for direct voltage readout of an electret micro- phone is presented. The ADC is integrated on the same chip with a bandgap voltage reference and is designed to be packaged to- gether with an electret microphone. Having a power consumption of 1.7 mW from a supply voltage of 1.8 V, the circuit is well suited for use in mobile applications. The single-loop, single-bit, fourth- order ADC operates at 64 times oversampling for a signal bandwidth of 11 kHz. The measured dynamic range is 80 dB and the peak signal-to-(noise distortion) ratio is 62 dB. The harmonic distortion is minimized by using an integrator with an instrumen- tation amplifier-like input which directly integrates the 125-mV peak single-ended voltage generated by the microphone. A com- bined continuous-time/switched-capacitor design is used to mini- mize power consumption. Index Terms—Analog-to-digital conversion, CMOS analog IC, continuous time, delta-sigma modulator, electret micro- phone, high input impedance, low-voltage bandgap reference, single-ended input, switched capacitor.

Configurable power amplifier and bias control

Abstract: The bias control (300) selectively provides for bias of a power amplifier (120) based upon a bandgap voltage (442) generated by the bias control, or by a bias voltage external to the bias control. A controller (420) controls the selection of either the bandgap voltage (442) or external bias voltage. The bias control is fabricated in a first semiconductor material capable of operating at low voltage supply levels, such as complementary metal oxide semiconductor (CMOS) material and may be fabricated on an integrated circuit common with a power amplifier.

Chopper stabilized bandgap reference circuit to cancel offset variation

Abstract: A bandgap reference circuit utilizes chopper stabilization to reduce reference voltage variation caused by, for example, offset voltage and 1/f noise within an associated amplifier. The input signal of the amplifier is modulated using a high frequency modulation signal. The modulated signal is then amplified and demodulated. In one embodiment, a single-ended chopper amplifier having integrated amplification/demodulation functionality is provided.

Low voltage bandgap circuit with improved power supply ripple rejection

Abstract: Methods and apparatus are disclosed for reducing output ripple voltages in bandgap voltage reference circuits. Ripple rejection circuitry is connected to a supply voltage and a first control signal, such as from an amplifier. The ripple rejection circuitry provides a second control signal representative of a difference between the supply voltage and the first control signal. The second control signal is then used to generate a reference voltage output. The incorporation of the supply voltage component in the second control signal operates to reduce or suppress the effects of power supply ripple on the bandgap voltage output.

Reference voltage stabilization in CMOS sensors

Abstract: A reference voltage generator for use in an image sensor provides a reference voltage to an S/H block during a pixel read-out operation and another reference voltage to an analog-to-digital converter (ADC) during a digitization operation. The reference voltage generator includes a variable voltage generator, a sample-and-hold circuit to sample a reference voltage prior to the pixel read-out operation or the digitization operation, and a buffer amplifier to drive the appropriate reference voltage to the relatively high impedance load presented by the S/H block and the variable impedance load provided by the ADC.

Bandgap voltage reference circuit

Abstract: An improved bandgap voltage reference circuit for providing a stable reference output voltage, useful in circuits associated with power supply voltage operations as low as approximately 1.3 Volts. The ΔV BE generator is comprised of a pair of bipolar transistors operating at different current densities. Resistors in series with the transistors, in conjunction with an operational amplifier and current sources, produce a larger Voltage drop proportional to the ΔV BE of the transistors. Output from the operational amplifier is connected to the base of a third bipolar transistor. The third bipolar transistor is provided as the bandgap voltage output device.

Voltage reference generation circuit and power source incorporating such circuit

Abstract: A voltage reference generation circuit is disclosed including a voltage reference generating stage and a voltage reference output stage, in which a depletion-mode MOS transistor and an enhancement-mode MOS transistor are connected in series, and the junction formed between these MOS transistors serves as an output terminal for outputting a voltage to be input to the voltage reference output stage. In the output stage, two enhancement-mode MOS transistors having the same channel dopant profile are connected in series between a power source and the ground, the gate of one MOS transistor is connected to the output terminal of the generating stage, the gate and drain of the other MOS transistor are interconnected, and the junction formed between these MOS transistors serves as an output terminal for a voltage reference. In addition, each of the enhancement-mode MOS transistors is provided with a floating gate having a different threshold voltage depending on, the coupling coefficient between the floating gate and a gate, the amount of charge input to the floating gate, the kind of dielectric material included in the gate, or the thickness of a gate oxide layer, which is suitably utilized to supply reference voltages with improved stability to fluctuations in operating temperatures or processing parameters.

Current mirror type bandgap reference voltage generator

Abstract: A current mirror type bandgap reference voltage generator which can reduce variations of a reference voltage due to temperature variations, by separately generating a current proportional to an emitter-base voltage and a current proportional to a thermal voltage, and which also can reduce variations of the reference voltage due to variations of a power voltage, by using a current mirror. The current mirror type bandgap reference voltage generator includes: a first current generator for generating a first current proportional to the emitter-base voltage; a second current generator for generating a second current proportional to the thermal voltage; and a reference voltage generator for adding the first and second currents, and generating a constant reference voltage regardless of variations of the temperature and the power voltage. As a result, the constant voltage is generated regardless of variations of the temperature and the power voltage.

Low voltage reset circuit device that is not influenced by temperature and manufacturing process

Abstract: A low voltage reset circuit device without being influenced by temperature and manufacturing process is formed by a first low voltage reset circuit using an energy gap circuit to generate a reference voltage, and a second low voltage reset circuit using a threshold voltage of a MOS transistor as a reference voltage. The first low voltage reset circuit is used to provide an accurate low voltage reset property,. while the circuit only works as VDD>1.2V. When VDD<1.2V, the second low voltage reset circuit still works normally for providing the desired reset signal thereby covering the low VDD voltage range.

Internal voltage generating circuit

Abstract: According to a reference voltage generated by a reference voltage generating circuit, a level shift circuit generates a control voltage with its level shifted from the reference voltage by a threshold voltage of a difference detection transistor. According to this control voltage, the difference detection transistor operates in a source follower mode to adjust a charged voltage of a capacitance element according to a voltage level of an internal voltage line. A current is supplied from a current drive circuit to the internal voltage line according to the charged voltage. In this way, an internal voltage is generated having a constant voltage level over a wide temperature range with a small occupying area and a small current consumption.

Low voltage supply bandgap reference circuit using PTAT and PTVBE current source

Abstract: A bandgap reference circuit comprising two NMOS transistors, where the first NMOS transistor is driven by a PTAT current source and the second transistor is driven by a PTVBE current source. The PTAT current (IPTAT) and PTVBE current (IPTVBE) are summed in a resistive circuit RX to generate the bandgap or sub-bandgap reference voltage. The IPTAT and IPTVBE currents are generated simultaneously in separate current sources and each of these currents is then used to gate the first and second transistor, respectively. The magnitude of the bandgap or sub-bandgap reference voltage is determined by the ratio of RX and a resistive circuit in the PTVBE current source. By requiring only two transistors, in parallel, coupled to resistive circuit RX the supply voltage required for all circuits is lower than heretofore possible.

A CMOS bandgap reference circuit

Abstract: Two types of CMOS bandgap reference circuits are presented in this paper, which can be used in many low voltage analog circuits. The simulation results show that the accuracy of the output bandgap voltages are 1.228/sup +/-0.003 V and 1.215/sup +/-0.003 V respectively over the process, voltage and temperature variations, and the dissipation in the bandgap references are less than 0.1 mW and 0.34 mW respectively, with the 3.3 v supply.

AC-DC converter with reduced energy loss through a switching element

Abstract: An AC-DC converter is provided which comprises a booster circuit 9 which has a MOS-FET 6 and a reactor 4 connected in series to MOS-FET 6 for generating a DC output voltage V OUT ; a voltage generator 11 for providing a reference voltage V R ; and a control circuit 10 for comparing reference voltage V R and DC output voltage V OUT and generating outputs to turn MOS-FET 6 ON and OFF in response to the difference between reference voltage V R and DC output voltage V OUT The control circuit 10 comprises a voltage detector 18 for measuring an input voltage V IN applied on an input terminal of the reactor 4; and a voltage retainer 22 for keeping output voltage V OUT on a level elevated by a substantially constant voltage V P +V R or V Z above input voltage V IN measured by voltage detector 18 such that booster circuit 9 simply raises input voltage V IN , even if on a lower level, by a substantially constant voltage with a smaller step-up ratio V OUT /V IN than that of a case for voltage increase up to a constant high DC output voltage regardless of a level of input voltage V IN

CMOS voltage reference

Abstract: A CMOS reference voltage generating circuit is described that produces a reference voltage by taking the difference between the gate-source voltages of two p-type and n-type CMOS transistors operating in the saturation region, one of the gate-source voltages being multiplied by a gain factor. Different circuits are described for situations where the n- or p-type transistors have the greater temperature dependence.

Low supply voltage, low quiescent current, ULDO linear regulator

Abstract: In this paper a new monolithic Ultra Low Drop-Out (ULDO) linear regulator developed in BCD (Bipolar CMOS, DMOS) technology, 5th generation, is described. It is able to deliver an output current up to 5 A with 150 mV drop-out voltage on the series element at a supply voltage down to 2 V The new regulator has been designed to reduce the quiescent and stand-by currents without degradation of the load transients performance and to guarantee an output voltage high accuracy, better than 1%, thanks to a new trimming structure. 200 /spl mu/A quiescent current and a very low stand-by current, up to 2 /spl mu/A, make the devices suitable for microprocessor applications such as Pentium, cellular phones, automotive and in all applications where power management and stand-by features are needed.

Bandgap reference voltage generator with a low-cost, low-power, fast start-up circuit

Abstract: A bandgap voltage reference generator includes a bandgap voltage reference circuit and a fast startup circuit. The fast start-up circuit, which is cost-efficient and saves power consumption, can rapidly start up the bandgap reference voltage circuit coupled thereto. The fast start-up circuit comprises a P-channel MOSFET or an N-channel MOSFET. Upon the bandgap voltage reference generator being powered by an external DC voltage, the bandgap reference generator will possibly operate in the power-down operating state. At this time there exists a large voltage drop between the gate and the source of the P-channel MOSFET (or N-channel MOSFET), and thus a large current flows rapidly through the P-channel MOSFET (or N-channel MOSFET). Voltages of drains of two specific MOSFETs in the bandgap voltage reference circuit will thus be pulled to be substantially the same, and the bandgap voltage reference circuit is brought into a normal operating state. The output of the bandgap reference generator is then very close to the bandgap voltage of silicon.

Supply voltage monitor using bandgap device without feedback

Abstract: A voltage monitor having a bandgap reference circuit driven by a voltage to be monitored. The bandgap reference circuit produces a voltage and a second voltage that each vary with the voltage to be monitored. The magnitudes of these voltages are compared by an open loop comparator to provide a high speed output state. The output of the voltage monitor can be used to monitor a supply voltage and produce a reset signal to a processor if the supply voltage falls to a magnitude below a specified threshold.

Low temperature coefficient reference current generator

Abstract: A low temperature coefficient reference current generator has a bandgap reference voltage generator for providing a low temperature coefficient bandgap reference voltage and a positive temperature coefficient current. The low temperature coefficient reference current generator utilizes the low temperature coefficient bandgap reference voltage to drive a positive temperature coefficient resistor disposed in an IC, so as to produce a negative temperature coefficient current. The positive temperature coefficient current and the negative temperature coefficient current are adjusted and combined to produce a low temperature coefficient reference current.

A CMOS 10GHz voltage controlled LC-oscillator with integrated high-Q inductor

Abstract: A 10GHz fully integrated Voltage Controlled Oscillator is presented. The circuit can be tuned from 8.1 GHZ to 10.9 GHz. This corresponds with a tuning range of 29.7%. The phase noise is -113dBc/Hz at 600kHz and - 127dBc/Hz at 3MHz. The VCO-core consumes 20 mA with a 2.5V power supply. The VCO is implemented in a 0.25µm 4 metal layer standard CMOS technology. The circuit's integrated inductor has a Q-factor of approximately 50 making it comparable to bondwire and discreet coils.

Voltage regulator for memory device

Abstract: A memory device includes a voltage regulator that compensates for resistance variations in the bit line control (multiplexing) circuit used to access the memory cells by including in its feedback path an emulated multiplexing circuit having an identical resistance to that of the multiplexing circuit. The voltage regulator also includes a differential amplifier, a pull-up transistor for generating a reference voltage, and a first clamp transistor controlled by the reference voltage to pass a desired voltage level to the multiplexing circuit. The feedback path incorporates the emulator circuit between a second clamp transistor and a voltage divider. Because the emulation and multiplexing circuits have the same resistance, the voltage passed to the voltage divider is essentially identical to the voltage passed by the multiplexing circuit to a selected memory cell, thereby allowing the voltage regulator to produce an optimal voltage level at the selected memory cell.