Stmicroelectronics S.r.l.

Roberto Modaffari

Germano Nicollini

Paolo Pesenti

Marco Garbarino

Federico Guanziroli

Tiziano Chiarillo

Mario Maiore

A delta-sigma modulator includes a quantizer, a signal propagation path including a plurality of cascaded integrators coupled between the input node and the quantizer, and a feedback network including a plurality of digital-to-analog converters. In a calibration mode of operation, a first digital-to-analog converter of the plurality of digital-to-analog converters of the feedback network receives a signal including a periodic alternated digital sequence, the first digital-to-analog converter being coupled to a first integrator of the plurality of cascaded integrators, integrators of the plurality of cascaded integrators other than the first integrator operate in a gain mode of operation, the delta-sigma modulator generates a digital test signal at an output of the quantizer based on the signal including the periodic alternated digital sequence, and calibration circuitry generates a calibration signal based on the digital test signal and a reference digital word.

Self-calibration circuit for delta-sigma modulators, corresponding device and method

A circuit includes an amplifier, a bias voltage node, and a first set of switches configured, based on a first reset signal having a first value, to couple first and second input nodes to the bias voltage node and to couple first and second output nodes of the amplifier. First and second feedback branches each include a respective RC network including a plurality of capacitances. The first and second feedback branches further include a second set of switches intermediate input nodes and the capacitances, and a third set of switches intermediate input nodes and the plurality of capacitances. These switches selectively couple the capacitances to the input nodes and output nodes, based on a second reset signal having a first value. The second reset signal keeps the first value for a determined time interval exceeding a time interval in which the first reset signal has the first value.

Charge amplification circuits and methods

A circuit for startup of a multi-stage amplifier circuit includes a pair of input nodes and at least two output nodes configured to be coupled to a multi-stage amplifier circuit. A startup differential stage includes a differential pair of transistors having respective control terminals coupled to the pair of input nodes, and each transistor in the differential pair of transistors has a respective current path therethrough between a respective output node and a common source terminal. The startup differential stage is configured to sense a common mode voltage drop at a first differential stage of the multi-stage amplifier circuit. Current mirror circuitry includes a plurality of transistors coupled to the common terminal of the differential pair of transistors and coupled to two output nodes of the at least two output nodes.

Multi-stage amplifier circuits and methods

A preamplifier circuit comprises a first pair of transistors and a second pair of transistors having current flow paths therethrough coupled at first and second output nodes and providing first and second current flow lines intermediate a supply node and ground. The two pairs of transistors comprise: first and second input transistors located intermediate the outputs nodes and one of the supply node and ground providing respective input nodes, first and second load transistors intermediate the output nodes and the other of the supply node and ground. The load transistors have control terminals capacitively coupled to the other of the supply node and ground and a reset switch arrangement is provided periodically activatable to short the first output node, the second output node as well as the control terminals of the first load transistor and the second load transistor.

Amplifier circuit, corresponding comparator device and method

A delta-sigma modulation circuit has a sampling period and, in operation, generates a delta-sigma modulated signal based on the analog input signal. The delta-sigma modulation circuit includes: a first integrator; an analog-to-digital converter; a feedback-loop coupled between an input of the first integrator and the output interface; a second integrator coupled between the first integrator and the analog-to-digital converter. The delta-sigma modulation circuit has loop-delay compensation circuitry having a plurality of switches. The loop delay compensation circuitry, in operation, controls the plurality of switches based on a time interval of a duration of half the sampling period and generates a loop-delay compensation signal.

Compensation circuit for delta-sigma modulators, corresponding device and method

A comparator circuit including: a first node and a second node, which receive a first current and a second current, respectively; a first current mirror, which includes a first load transistor and a first output transistor; and a second current mirror, which includes a second load transistor and a second output transistor. The comparator circuit further includes: a first feedback transistor and a second feedback transistor cross-coupled together, the control terminals of the first and second feedback transistors being connected to the first and second nodes, respectively; a first resistor, having a first terminal, which is connected to the control terminal of the first load transistor, and a second terminal, which is connected to the first node and to the control terminal of the first output transistor; and a second resistor, having a first terminal, connected to the control terminal of the second load transistor, and a second terminal, connected to the second node and to the control terminal of the second output transistor.

High-speed continuous-time comparator circuit

A phase shifter, which carries out a ninety-degree phase shift of a sinusoidal input signal having an input frequency, at the same input frequency, envisages: a continuous-time all-pass filter stage, which receives the sinusoidal input signal and generates an output signal phase-shifted by 90&#xb0; at a phase-shift frequency that is a function of a RC time constant of the all-pass filter stage; and a calibration stage, which is coupled to the all-pass filter stage and generates a calibration signal for the all-pass filter stage, such that the phase-shift frequency is equal to the input frequency of the sinusoidal input signal, irrespective of variations of the value of the input frequency and/or of the RC time constant with respect to a nominal value.

Ninety-degree phase shifter circuit and corresponding ninety-degree phase-shifting method

An amplifier includes a first input branch and a second input branch that form a differential input stage and a current mirror connected to the differential input. The current mirror is governed as a function of a common mode feedback signal applied to a control node of the current mirror. A second, amplification, stage includes a branch flowing through which is a current, which is a function of the current that flows in the first input branch, and is in turn connected to a first output branch. A capacitive element is coupled between the control node and the second stage. The circuit is symmetrical with respect to the input stage.

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Pallanzeno, Italy

Roberto Modaffari