Sgs-thomson Microelectronics S.r.l.

Consorzio Per La Ricerca Sulla Microelettronica Nel Mezzogiorno

Giuseppe Patti

Melchiorre Bruccoleri

Marco Pio Demicheli

Gaetano Cosentino

Davide Demicheli

Marco DeMicheli

Valerio Pisati

David Demicheli

A servo-demodulator for a pair of alternating signals generated by a magnetic disc read head and indicative of the position of the read head in relation to the center of a recorded track. The servo-demodulator comprises a peak detector for successively and individually sampling the amplitude of each of a plurality of peaks of the pair of alternating signals, and a capacitor periodically connected to the output of the peak detector by a control logic for deriving a weighted average of the various successively sampled amplitudes. In this manner, the control logic obtains an averaged measure of amplitude with high immunity to noise.

Circuit and method for determining the position of a read head for a magnetic disk drive device

Magnetic disc read head positioning device and method

A circuit having a double half-wave rectifier connected to the outputs of a differential amplifier in order to produce two quantities dependent on the amplitudes of the half-waves of the output signal of the amplifier. Two comparators each having an input are connected to an output of the rectifier and a reference input in order to produce respective output signals when the amplitudes of the respective half-waves are greater than the levels applied to the reference inputs. The circuit also has processing means for generating a signal for regulating the gain of the amplifier in dependence on the durations of the output signals of the two comparators. The circuit may advantageously be used when the signal to be amplified is not symmetrical.

Circuit for automatically regulating the gain of a differential amplifier

A current generator stage for integrated analog circuits includes a current source connected between a supply voltage and a ground terminal. A current mirror is operationally connected to the current source to generate an output current. A bias circuit is operationally connected to the current source to perform switching of the current source from a first operating mode to a second operating mode. The bias circuit includes an energy storage circuit which, in a first circuit configuration, supplies to the current source a first predetermined voltage when the current source is in the first operating mode. The energy storage circuit in a second circuit configuration is a combination of first and second reactances to supply to the current source a second predetermined voltage when the current source is in the second operating mode.

Current generator stage used with integrated analog circuits

A digital/analog quadratic converter (DACQ) composed by a pair of linear converters connected in cascade has a direct coupling of the output node of the first converter (DAC1) with a node of a R-2R type resistive network of the second converter (DAC2) corresponding to the LSB stage of the R-2R type resistive network. High impedance nodes, notably the input node of the second linear converter, are advantageously eliminated from the 'current path' thus markedly reducing the problems of relatively long settling times of high impedance nodes (having intrinsically large parasitic capacitances associated therewith). The peculiar architecture of the quadratic converter provides also for a remarkable simplification of the circuit.

Reduced current quadratic digital/analog converter with improved

A differential charge pump circuit employing a lowpass filter network which is chargeable and dischargeable by switchingly controlled current generators. The differential charge pump employs two identical current generators for injecting the same current I in a substantially continuous manner, on the two significant nodes of the lowpass filter. The differential charge pump also employs two pairs of identical, switchingly controlled current generators connected to the two significant nodes, respectively, each capable of pulling a current I. The two generators forming each of the two pairs of switchingly controlled current generators are controlled by one of a pair of control signals (UP, DOWN) and by the inverted signal of the other of the pair of control signals, respectively. All four switchingly controlled generators may be of the same type (N-type), thus ensuring high speed and precision. The two identical (P-type) current generators employed for continuously injecting the same current I on the two nodes of the lowpass filter may be controlled through a common mode feedback loop for enhanced precision.

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Favara, Italy

Giuseppe Patti