Apparatus and method of fabricating mixed signal interface in GSM wireless application
First Claim
1. An integrated circuit comprising:
- a first circuit for processing a first analog signal and producing a first digital output;
a second circuit for processing a second analog signal and producing a second digital output;
a third circuit for processing a third analog signal and producing a third digital output;
a first digital subtractor circuit, connected to said first circuit and connected to said second circuit, to subtract said second digital output from said first digital output; and
a second digital subtractor circuit, connected to said third circuit and connected to said second circuit, to subtract said second digital output from said third digital output.
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Abstract
A analog-to-digital conversion apparatus and method for mobile communication devices are disclosed by the present invention. Because the conventional CMOS process does not allow for high order anti-aliasing circuits to be fabricated with digital circuits on the same chip, a new apparatus had to be developed to use low order anti-aliasing filters for the analog-to-digital conversion. The apparatus of the present invention includes a low order anti-aliasing circuit, a delta-sigma converter, and post-conversion filters. The post conversion filters include a decimation circuit, a droop correction filter, and an offset adjust circuit. In this implementation, a low order analog anti-aliasing filter can be used along with a delta-sigma converter and post-conversion filters to eliminate the need for high order analog anti-aliasing filters. Another aspect of the present invention is the duplication of the circuits to process the incoming signals. The duplicate circuit is fed a null signal to process the noise only. Then, the processed noise is subtracted from the processed signals, which contain the information plus noise, to obtain a noise free processed signal.
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Citations
37 Claims
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1. An integrated circuit comprising:
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a first circuit for processing a first analog signal and producing a first digital output; a second circuit for processing a second analog signal and producing a second digital output; a third circuit for processing a third analog signal and producing a third digital output; a first digital subtractor circuit, connected to said first circuit and connected to said second circuit, to subtract said second digital output from said first digital output; and a second digital subtractor circuit, connected to said third circuit and connected to said second circuit, to subtract said second digital output from said third digital output. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An integrated circuit comprising:
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a first circuit for processing a first analog signal and producing a first output; a second circuit for processing a second analog signal and producing a second output; a third circuit for processing a third analog signal and producing a third output; a first analog subtractor circuit, connected to said first circuit and connected to said second circuit, to subtract said second output from said first output; and a second analog subtractor circuit, connected to said third circuit and connected to said second circuit, to subtract said second output from said third output. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A method for converting analog signals to digital signals, said method comprising:
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filtering an analog signal using a lower order anti-aliasing filter to produce a filtered signal; sampling said filtered signal using a delta-sigma converter to produce digital samples; digitally filtering said digital samples to produce a digital signal output; filtering a null input signal using a second lower order anti-aliasing filter to produce noise signal; sampling said noise signal using a delta-sigma converter to produce digital noise samples; digitally filtering said digital noise samples to produce a digital noise output; and subtracting said digital noise output from said digital signal output. - View Dependent Claims (32)
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33. A method for converting analog signals to digital signals, said method comprising:
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filtering an analog signal using a lower order anti-aliasing filter to produce a filtered signal; sampling said filtered signal using a delta-sigma converter to produce digital samples; digitally filtering said digital samples to produce a digital signal output; filtering a null input signal using a second lower order anti-aliasing filter to produce a noise signal; and subtracting said noise signal from said filtered signal prior to sampling said filtered signal. - View Dependent Claims (34)
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35. A single chip useful in wireless communications for receiving and transmitting radio signals, the semiconductor device comprising:
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an analog-to-digital converter (ADC) to convert incoming analog signal to digital signal; a digital signal processor (DSP), connected to said ADC, to code, decode, modulate, and demodulate the digital signal; an audio digital-to-analog converter (audio-DAC), connected to said DSP, to convert processed digital signal to audio analog signal; an audio analog-to-digital converter (audio-ADC), connected to said DSP, to convert audio analog signal to audio digital signal; and a digital-to-analog converter (DAC), connected to said DSP, to convert coded and modulated digital signal to analog signal suitable for transmission. - View Dependent Claims (36, 37)
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Specification