Coded data generation or conversion – Analog to or from digital conversion – Nonlinear
Reexamination Certificate
2006-10-31
2006-10-31
Nguyen, Linh (Department: 2819)
Coded data generation or conversion
Analog to or from digital conversion
Nonlinear
C341S133000
Reexamination Certificate
active
07129872
ABSTRACT:
An apparatus for converting an input analog audio signal into digital form including an analog-to-digital converter. An amplifier circuit and step-down transformer provide an interface for the input analog audio signal to the analog-to-digital converter. The step-down transformer includes a primary winding operably coupled to the amplifier circuit and a secondary winding operably coupled to the analog-to-digital converter. The amplifier circuit drives the primary winding with the input analog audio signal (or an amplified version thereof). The step-down transformer generates a stepped-down representation of the input analog audio signal at its secondary winding. Advantageously, the step-down transformer lowers the effective output impedance of the amplifier circuit, which reduces distortion in the audio analog input signal supplied to the analog-to-digital converter. In addition, the step-down transformer reduces (by the factor 1/N) the demand placed on amplifier circuit in charging a sampling capacitor typically realized as part of the input stage of the analog-to-digital-converter.
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