Maxim Integrated Products, Inc.

U.S. Philips Corporation

Philips Electronics North America Corporation

Koninklijke Philips Corporation N.v.

Nxp B.v.

Signetics

North American Philips Corp, Signetics Division

Bronkhorst High-tech B.v.

North American Philips Corporation

Mierij Meteo B.v.

Maxim Integrated Prodcuts, Inc.

Signetics Company

Johan Hendrik Huijsing

Behzad Shahi

Anthonius Bakker

John P Tero

Kofi Afolabi Anthony Makinwa

Klaas-Jan De Langen

Kofi A A Makinwa

Qinwen Fan

Maarten J Fonderie

Ronald Hogervorst

Michiel Pertijs

Maarten Jeroen Fonderie

Rudolphe G Eschauzier

Rong Wu

Frank R Riedijk

Michiel A P Pertijs

Jun Wu

Rudy J Van De Plassche

Edmond Toy

Herman Schutte

Richard Edward Boucher

Gerrit Van Der Horn

Johan Frederik Witte

Timothy A Dhuyvetter

Daihong Fu

Roelof F Wassenaar

Martinus Bredius

Roeland F Tuk

Michiel A P Pertus

Lixia Zhou

Huibert Jan Verhoeven

Bastiaan Willem Van Oudheusden

Arend Hagedoorn

Marien G Maris

Kofi Anthony A Makinwa

Remco J Wiegerink

Ron Hogervorst

A method of differential signal transfer from a differential input Vinp and Vinn having a common mode input voltage that can be higher than the power supply voltage by providing an input chopper having first through fourth chopper transistors, each having a source, a drain and a gate, the input chopper having Vinp and Vinn as a differential input, providing an output chopper, capacitively coupling a differential output Voutp and Voutn of the input chopper to a differential input of the output chopper, capacitively coupling a clock to the input chopper and coupling the clock to the output chopper, the clock having a first phase and a second phase opposite from the first phase, the first phase being coupled to the gates of the first and second transistors and the second phase being coupled to the gates of the third and fourth transistors, and providing protection of the gates of the first through fourth transistors from excessive voltages. Various embodiments are disclosed.

Fully capacitive coupled input choppers

Fast-settling capacitive-coupled amplifiers are disclosed. The amplifiers use two Capacitive Coupled paths embedded in a Multipath Hybrid Nested Miller Compensation topology. One path is a direct high frequency path and the other path is a slower stabilization path. This combination results in a flat frequency response to and through the chopper frequency, and a fast settling response. Various exemplary embodiments are disclosed, including operational amplifier and instrumentation amplifier configurations.

Fast-settling capacitive-coupled amplifiers

A method of differential signal transfer from a differential input Vinp and Vinn having a common mode input voltage that can be higher than the power supply voltage by providing an input chopper having Vinp and Vinn as a differential input, providing an output chopper, capacitively coupling a differential output Voutp and Voutn of the input chopper to a differential input of the output chopper, capacitively coupling a clock to the input chopper and coupling the clock to the output chopper, the clock having a first phase and a second phase opposite from the first phase, the first phase being coupled to the gates of the first and second transistors and the second phase being coupled to the gates of the third and fourth transistors, and providing protection of the gates of the first through fourth transistors from excessive voltages. Various embodiments are disclosed.

Current-feedback instrumentation amplifiers that include dynamic element matching for the input transconductance amplifiers by periodically swapping the transconductance amplifiers between the instrumentation amplifier input and the feedback input. The instrumentation amplifiers may include a gain error reduction loop, which loop corrects differences in the gains of the input transconductance amplifiers and eliminates the ripple in the instrumentation amplifier output caused by the dynamic element matching. If chopper stabilization is used, the amplifiers may also include an offset reduction loop. Various embodiments are disclosed.

Current-feedback instrumentation amplifiers

Ripple reduction loop for chopper amplifiers and chopper-stabilized amplifiers. The ripple reduction loop includes a first chopper, a first amplifier having an input coupled to an output of the first chopper, a second chopper having an input coupled to an output of the first amplifier, a second amplifier having an input coupled to an output of the second chopper, a third chopper, an output of the second amplifier having its output capacitively coupled to an input of the third chopper as the only input to the third chopper, a third amplifier coupled as an integrator having an input coupled to an output of the third chopper, an output of the integrator being coupled to combine with the output of the first amplifier as the input of the second chopper, and at least one Miller capacitor coupled between an output of the second amplifier and the input of the second amplifier. Various embodiments are disclosed.

Ripple reduction loop for chopper amplifiers and chopper-stabilized amplifiers

Auto-gain correction in a precision amplifier provides continuous calibration of the gain of the two differential input stages relative to each other and thus significantly minimizes the effects of device mismatch and temperature. Auto-gain correction together with auto-zero minimizes the effects of common mode input voltage on the amplifier and eliminates the need for trim associated with the matching of the two differential input stages. Improved gain matching enhances the accuracy of the auto-zero, which further improves the accuracy of auto-gain correction, resulting in a synergy with both operating together. The implementation of the auto-zero using an input pair of series capacitors in conjunction with a common input reference and a feedback pair of series capacitors in conjunction with a common feedback reference provides for decoupling the common mode voltage of the input differential pair or feedback differential pair. Various features may be used in sub-combinations as desired.

Auto-gain correction and common mode voltage cancellation in a precision amplifier

A method for calibrating a digital temperature sensor circuit, the circuit comprising an analogue temperature sensing means, an internal reference voltage source and an analogue-to-digital converter (ADC). The ADC is arranged to receive respective signals from the analogue temperature sensing means and the reference voltage source and output a digital signal indicative of the ambient temperature. The method comprises the steps of determining the value of the internal reference voltage outputted by the reference voltage source, comparing it with the desired reference voltage value, and adjusting the reference voltage source in response to the result of the comparison step. Such an electrical voltage mode calibration can significantly reduce production costs, as it can be performed much faster than a traditional thermal calibration. The method can be applied to a sensor that produces a PTAT voltage that has to be compared to a temperature-independent bandgap reference voltage.

Digital temperature sensors and calibration thereof

Chopper stabilized amplifiers combining low clock noise and linear frequency characteristics. The chopper stabilized amplifiers are used in offset correction circuitry, with the output of the chopper stabilized amplifiers being integrated by an integrator. The integrator operates on alternate cycles, with a sample and hold circuit sampling the integrator output when the integrator is not integrating, with the output of the sample and hold being coupled to the main amplification path to cancel offset after at least some amplification is achieved. Autozeroing of amplifiers in the offset correction circuitry is also disclosed. The invention is applicable to operational amplifiers and instrumentation amplifiers.

Chopper stabilized amplifiers combining low chopper noise and linear frequency characteristics

A bias circuit for use in bandgap voltage reference circuits and temperature sensors comprises a pair of transistors (Q, Q2), the first of which (Q1) is arranged to be biased at an emitter current, and the second of which (Q2) is arranged to be biased at an emitter current of m.lbi. The circuit is arranged such that the difference between the base-emitter voltages of the transistors is generated in part across a first resistance means having a valueand in use carrying a bias current equal toand in part across a second resistance means of value substantially equal toand in use carrying a current equal to the base current of the second transistor. This results in use in a bias current Iwhich, when used to bias a substrate bipolar transistor via its emitter, produces a collector current therefrom which is substantially PTAT and a base-emitter voltage which is substantially independent of the forward current gain of the substrate bipolar transistor.

Bias circuits

When a reference signal is generated for a digital-to-analog converter in the feedback path of a sigma-delta modulator, the reference signal can contain modulated error signals, for example when the reference generator implements dynamic element matching. By controlling the reference signal generation in dependence on the bitstream output from the sigma-delta modulator, the effects of intermodulation of the reference signal with the bitstream can be reduced.

Bitstream controlled reference signal generation for a sigma-delta modulator

Frequency stabilization of chopper-stabilized amplifiers using multipath hybrid double-nested Miller compensation. The compensation may provide a desired 6 dB/oct roll off for both instrumentation amplifiers and operational amplifiers. Various embodiments are disclosed.

Frequency stabilization of chopper-stabilized amplifiers

Accurate voltage to current converters for rail-sensing current-feedback instrumentation amplifiers using folded cascode transistors. Embodiments using various degrees of cascoding, as well as using bootstrapped folded cascoded input transistors are disclosed. Circuits for sensing around the negative rail are disclosed, though circuits for sensing around the positive rail may be readily achieved by use of complementary devices.

Accurate voltage to current converters for rail-sensing current-feedback instrumentation amplifiers

Chopper chopper-stabilized instrumentation and operational amplifiers having ultra low offset. The instrumentation amplifiers use current-feedback, and include, in addition to a main chopper amplifier chain, a chopper stabilized loop for correcting for the offset of the input amplifiers for the input signal and for receiving the feedback of the output voltage sense signal. Additional loops, which may include offset compensation and autozeroing loops, may be added to compensate for offsets in the chopper stabilized loop for correcting for the offset of the input amplifiers. Similar compensation is disclosed for decreasing the offset in operational amplifiers.

Chopper chopper-stabilized instrumentation and operational amplifiers

An amplifier (AMP) is provided with a pair of choppers (CHP,CHP) in order to reduce the DC-offset and the noise produced by the amplifier (AMP). To obtain an optimal noise reduction the pair of choppers (CHP,CHP) operate on a high frequency. As a result the DC-offset cancellation is not optimal because a so-called charge injection of the switches in the pair of choppers (CHP,CHP) produces a DC-offset. To overcome this problem the amplifier (AMP) is further provided with further offset cancellation means which are for example formed by a further pair of choppers (CHP,CHP). This further pair of choppers (CHP,CHP) operates on a relatively low frequency. The combination of the pair of choppers (CHP,CHP) and the further pair of choppers (CHP,CHP) guarantees an optimal DC-offset cancellation as well as an optimal noise cancellation.

Circuit, including feedback, for reducing DC-offset and noise produced by an amplifier

An amplifier topology that combines the use of chopping and chopper stabilization, and may include auto-zeroing to achieve this very low offset. The use of choppers guarantees a very low offset, and moreover, eliminates the so-called 1/f noise. Chopper stabilization is used to avoid the so-called chopper noise associated with chopper amplifiers. The auto-zeroing technique may be used to improve the performance of the chopper-stabilization circuitry. Various exemplary embodiments are disclosed.

Chopper chopper-stabilized operational amplifiers and methods

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Schipluiden, Netherlands

Johan Hendrik Huijsing