Sgs-Thomson Microelectronics S.r.l.

Elia Pagani

Giovanni Avenia

Andrea Fassina

Adriano Lanzi

A method and device for measuring the switching noise of an audio amplifier by measuring the energy of the noise signal at the output of the audio amplifier as the amplifier is switched from one operating condition to another by a control signal, and after first weighing the energy according to the frequency and volume sensitivity of the human ear. The device comprises a control signal generator; an audio band filter connected to the output of the audio amplifier; a meter for measuring the power of the filtered signal; and an integrating element for calculating the energy of the filtered signal.

Audio amplifier switching noise measuring method and device

A test method whereby a high current is supplied to a first pin of an integrated device to be tested, and the variation in the voltage drop between the first pin and a second pin on the device to be tested is determined; the two pins being connected to two pads in turn connected, inside the device to be tested, by a low-voltage-drop path. The variation in the voltage drop of the device to be tested is compared with the measured nominal variation of an undoubtedly sound device of the same type, to determine any excessive deviation indicative of deficiency. The supply current in fact results in power dissipation, local heating and, consequently, a variation in the resistance of the connecting wires or of the die attachment to the lead frame, the extent of which differs according to whether only one or both of the wires of a two-wire connection to be tested are present, and according to whether the die is attached properly, poorly or badly to the lead frame. This variation in resistance is reflected in the amount or speed by which the detected voltage drop varies, thus enabling sound parts to be distinguished from faulty ones.

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Bergamo, Italy

Elia Pagani