Quad-flat packages with a leadframe made of copper (Cu), or alloy42 are widely used for CMOS digital applications. As the clock speed ofCMOS VLSIs increases, the package inductance is considered to be alimiting factor for their performance. To investigate the relationshipbetween package inductance and switching noise, three types of leadframematerials, Cu, alloy 42, and Ag-plated alloy 42 were prepared.Frequency-dependent properties of leadframe materials were measured upto a high frequency range. Then, extensive experiments were executed byusing a CMOS noise generating chip to measure how leadframe materialsinfluence switching noise in conjunction with output buffercharacteristics. The alloy 42 leadframe is believed to be unsuitable forhigh-speed CMOS applications because of its high permeability offerromagnetics. However, it has been proved that the large inductancedifference at lower frequencies does not greatly affect switching noiseat practical operating frequencies. A modeling approach for leadframepackages was executed by taking mutual inductances into considerationand by using the measured values of inductances and resistance
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