A first amplifier circuit includes differential pair transistors that amplify a difference between input voltages and active load transistors connected to the differential pair transistors. A second amplifier circuit amplifies output voltage of the first amplifier circuit. An offset correction current source is connected in parallel with the active load transistors and adjusts electric current flowing through the differential pair transistors correct offset voltage. An offset correction switch switches a driving state of the offset correction current source. A transconductance proportional current generation circuit generates transconductance proportional current for compensating for temperature drift of offset correction voltage for correcting the offset voltage. The transconductance proportional current is proportional to transconductance.

An apparatus, system, and method are disclosed for compensating input offset of an amplifier having first and second amplifier output nodes. The method comprises generating a proportional-to-absolute temperature (PTAT) current, generating a complementary-to-absolute temperature (CTAT) current, and selecting, based on the input offset, one of the first and second amplifier output nodes into which a compensation current is to be coupled. The compensation current is based on a selected one of the PTAT current and CTAT current.

A method includes providing a first voltage to a first output node during a first time interval, providing a second voltage to the first output node during a second time interval, and averaging the first and second voltages to provide a reference voltage to a second output node. The first voltage includes a proportional-to-absolute-temperature (PTAT) component, a complementary-to-absolute-temperature (CTAT) component, and a first residual offset component. The second voltage includes the PTAT component, the CTAT component, and a second residual offset component. An apparatus includes a discrete-time circuit to provide the first voltage to the first output node during the first time interval and to provide the second voltage to the first output node during the second time interval, and a filter to average the first and second voltages to provide the reference voltage to the second output node.

A differential operational amplifier, which comprises: a voltage adjusting module, coupled between a first predetermined voltage source and a second predetermined voltage source, for adjusting a first voltage via a first voltage adjusting value to generate a first adjusted voltage, and for adjusting a second voltage via a second voltage adjusting value to generate a second adjusted voltage, wherein the first voltage adjusting value and the second voltage adjusting value change corresponding to a temperature; and a differential signal computing module, coupled between the first predetermined voltage source and the second predetermined voltage source, for generating an output voltage according the first adjusted voltage and the second adjusted voltage.

The present invention relates to an operational amplifier, including: a symmetrical differential amplifier; a local common mode feedback circuit coupled to the symmetrical differential amplifier; a tail current source circuit including at least one first transistor and a second transistor and a current source resistor. The tail current source circuit is configured to adjust a control voltage of the first transistor by using the second transistor such that a predetermined reference current flows through a load path of the first transistor.

An operational amplifier (OPAMP) is biased with a tail current that varies with temperature and process in order to compensate for variations in amplifier bandwidth. A proportional to absolute temperature (PTAT) current source generates a PTAT current producing a reference voltage. A voltage-to-current generator circuit utilizing a differential amplifier circuit converts the reference voltage to a reference current from which the tail current is derived. Resistors coupled to the PTAT current source and the voltage-to-current generator circuit have resistance values dependent on operating temperature, wherein such resistors are matching of the resistors used for a gain setting circuit of the OPAMP.

A first correction voltage generation circuit provides a first positive or negative correction voltage for correcting an input voltage. A second correction voltage generation circuit provides a second correction voltage identical in polarity to the first correction voltage in accordance with the first correction voltage. The second correction voltage is generated to have a temperature coefficient reverse in polarity to a temperature coefficient of the first correction voltage.

The present disclosure relates to a current sensor, including a magnetic-field sensor for measuring a magnetic field induced by an electrical current; an output connection for providing an amplified measurement signal from the magnetic-field sensor, the magnetic-field sensor and the output connection being connected by an analog signal path having at least one amplifier, the analog signal path having a frequency response; a temperature sensor for measuring a temperature; and a compensation circuit which is coupled to the analog signal path and is configured to correct the frequency response of the analog signal path based on the temperature.