Patent ID: 6879274
Filing Date: 2005-04-12
Classification: H03M

Abstract:
1. An analog-to-digital device, comprising: a first programmable gain amplifier to amplify a first voltage signal from a first channel; a second programmable gain amplifier to amplify a second voltage signal from a second channel; a first analog-to-digital converter to convert the amplified first voltage signal to a first digital signal; a second analog-to-digital converter to convert the amplified second voltage signal to a second digital signal; a first lowpass filter circuit, receiving said first and second digital signals, to generate, therefrom, a filtered digital signal; a direct digital synthesizer to generate a third digital signal representing a predetermined waveform; a first multiplier to multiply said second voltage signal and said digital signal representing the predetermined waveform to generate a digital value; a phase shifter circuit, operatively connected to said first multiplier, to generate a signal representing a 90-degree phase shift of said digital value; a second multiplier, operatively connected to said phase shifter circuit and said first analog-to-digital converter, to multiply the signals therefrom and to produce a 90-degree phase signal; a third multiplier, operatively connected to said first multiplier and said first analog-to-digital converter, to multiply the signals therefrom and to produce a zero degree phase signal; a second lowpass filter circuit, operatively connected to said second and third multipliers, to filter said 90 degree and zero degree phase signals; a first root-mean-square circuit to convert the filtered zero degree phase digital signal into an In-Phase signal; and a second root-mean-square circuit to convert the filtered 90-degree phase digital signal into a Quadrature signal.