Analog Devices,inc.

Chau Cuong Tran

Moshe Gerstenhaber

A Paul Brokaw

David Hall Whitney

Derek F Bowers

John Albert Geen

Adrian P Brokaw

Geoffrey Thomas Haigh

Sandro Herrera

Alasdair Gordon Alexander

Oljeta Bida Qirko

Mark Fazio

An amplifier includes a bootstrap circuit for improving a linearity of the amplifier and a feed-forward circuit for modifying a voltage of the bootstrap circuit in response to a change in an input signal. Modifying the voltage using the feed-forward circuit prevents a phase-inversion condition of the amplifier.

Feed-forward circuit to prevent phase inversion

A system and method for reducing gain error and distortion in an operational amplifier due to errors in the second or integrator stage. A correction circuit may replicate an error current and insert the current into the signal stream to preempt the induction of an error at the amplifier's input. A capacitor may sample the error voltage at the input of the integrator stage of the amplifier and generate a replica of the error current in the integration capacitor to feed it into the input of the integrator stage. This eliminates any nonlinearity errors created by error currents in the compensation or integration capacitor at the second or integrator stage of the two-stage amplifier. Feeding the error current to the integrator stage may be facilitated with a unity gain buffer and a current mirror.

Integrator distortion correction circuit

A temperature setpoint circuit comprises bipolar transistors Qand Qwhich receive currents Iand Iat their respective collectors and are operated at unequal current densities, with a resistance Rconnected between their bases such that the difference in their base-emitter voltages (&#x394;V) appears across R. An additional PTAT current Iis maintained in a constant ratio to Iand Iand provided to the collector of Qwhile Qis off, and is not provided while Qis on. The circuit is arranged such that Qis turned on and conducts a current equal to Ia when: &#x394;V=(kT/q)ln(NI/Ia), where Ia=I+I, the temperature T at which &#x394;V=(kT/q)ln(NI/Ia) being the circuit's setpoint temperature, such that the switching of current Iprovides hysteresis for the setpoint temperature which is approximately constant over temperature.

Temperature setpoint circuit with hysteresis

A repatterned integrated circuit chip package which balances and/or reduces the package capacitance associated with the gain resistor terminals to reduce the degradation of common mode rejection with frequency.

Repatterned integrated circuit chip package

A multiple differential amplifier system and method for transconductance mismatch compensation which in a first phase connects to a differential switched input of a null amplifier, the differential signal input of the main amplifier, inverted, for compensating for offset errors and transconductance mismatches in the null amplifier; and storing in a null storage device connected to an auxiliary input of the null amplifier the output of the null amplifier representing the compensation for the offset error and transconductance mismatch of the null amplifier; and in a second phase connecting the differential switched input of the null amplifier to the differential feedback input of the main amplifier and storing in the main storage device connected to an auxiliary input of the main amplifier the output of the null amplifier representing the compensation for the main amplifier offset error and transconductance mismatch.

Multiple differential amplifier system and method for transconductance mismatch compensation

A bandgap voltage regulator is arranged such that, when a desired output voltage is present between its output and common terminals, current densities in a pair of bipolar transistors having unequal emitter areas are maintained in a fixed ratio. The difference in the transistors' base-emitter voltages is across a resistor, which thus conducts a PTAT current. The regulator also generates a CTAT current, and both the PTAT and CTAT currents are made to flow in another resistor, with the resulting voltages added by superposition. The regulator's resistors are sized such that Vis an integral or fractional multiple of V, where Vis the bandgap voltage for the fabrication process used to make the regulator's transistors, such that Vis temperature invariant, to a first order. The resistors are preferably realized using unit resistors having a predetermined resistance, or series and/or parallel combinations of unit resistors.

Bandgap voltage regulator

A low quiescent power class AB current mirror circuit includes a first input transistor for receiving an input current and a second output transistor for providing an output current; the first and second transistors having bases connected together; and a first current supply for sinking current from the bases in response to a decrease in input current to lower the quiescent point of the transistors.

Low quiescent power class AB current mirror circuit

A high gain amplifier includes an intermediate gain stage; an output gain stage driven by the intermediate gain stage; an input stage, for driving the intermediate gain stage, which is balanced between positive and negative feedback in normal operation; bias means for driving the input stage to maintain balance between positive and negative feedback in normal operation; and a resistance for limiting the output current of the intermediate stage in response to the input stage being overdriven into positive feedback.

High gain amplifier with current limited positive feedback

A current compensation circuit for an amplifier, for example an operational amplifier, having input and output stages coupled at a high-impedance node, compensates for any modulation of current occurring at the high-impedance node. Particularly, the compensation circuit of the present invention reduces the error current at the high-impedance node resulting from a mismatch in beta between PNP and NPN transistors in the output stage, and reduces any error current resulting from the Early voltage effects of transistors in the output stage. In this manner, the present invention serves to substantially isolate the amplifier input stage from the output load, and from any beta mismatch or Early voltage effects in the transistors of the output stage, resulting in greatly improved open-loop gain.

Current compensation circuit for improved open-loop gain in an amplifier

A semiconductor magnetic field sensor including a substrate; a semiconductor moveable element suspended above the substrate, the moveable element being configured to have a current passed therethrough and to deflect perpendicularly with respect to an applied magnetic field; and at least one fixed semiconductor element arranged adjacent to the moveable element, the moveable element being deflected to or away from the fixed element in response to an applied magnetic field. In an alternative embodiment of the invention, there is provided a semiconductor magnetic field sensor including a substrate; first and second semiconductor moveable beams suspended above the surface of the substrate, the first and second beams being configured to have equal and opposite currents passed therethrough and to deflect perpendicularly with respect to an applied magnetic field; and at least one first and second fixed semiconductor elements arranged adjacent to the first and second beams, respectively, the first and second beams being deflected to or away from the respective first and second fixed elements in response to an applied magnetic field.

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Malden, MA, United States of America

Chau Cuong Tran