Programmable input range ADC
First Claim
1. A programmable input voltage range analog-to-digital converter comprising:
- an analog-to-digital converter (ADC) having a characteristic dynamic range; and
an input voltage scaling network in which the input voltage is sampled onto one or more selected sampling capacitors to scale the input voltage to substantially match the characteristic dynamic range of the ADC.
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Abstract
A programmable input voltage range analog-to-digital converter in which a split gate oxide process allows the use of high voltage (±15 volt) switches on the same silicon substrate as standard sub-micron 5 volt CMOS devices. With this process, the analog input voltage can be sampled directly onto one or more sampling capacitors without the need for prior attenuation circuits. By only sampling on a given ratio of the sampling capacitors, the analog input can be scaled or attenuated to suit the dynamic range of a subsequent ADC. In the system of the present invention, the sampling capacitor can be the actual capacitive redistribution digital-to-analog converter (CapDAC) used in a SAR ADC itself, or a separate capacitor array. By selecting which bits of the CapDAC or separate sampling array to sample on, one can program the input range. Once the analog input signal has been attenuated to match the allowed dynamic range of the SAR converter, traditional SAR techniques can be used to convert the input signal to a digital word. Other conversion technologies, such as sigma-delta and pipeline, can also be used in conjunction with the inventive system.
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Citations
55 Claims
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1. A programmable input voltage range analog-to-digital converter comprising:
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an analog-to-digital converter (ADC) having a characteristic dynamic range; and
an input voltage scaling network in which the input voltage is sampled onto one or more selected sampling capacitors to scale the input voltage to substantially match the characteristic dynamic range of the ADC. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A programmable input voltage range analog-to-digital converter comprising:
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an analog-to-digital converter (ADC) having a characteristic dynamic range; and
an input voltage scaling network including an array of parallel-connected sampling capacitors in an input amplifier providing a sampled input voltage to the ADC;
such that the input voltage is sampled onto one or more selected sampling capacitors to scale the input voltage to substantially match the characteristic dynamic range of the ADC. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A programmable input voltage range analog-to-digital converter comprising:
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an analog-to-digital converter (ADC) having a characteristic dynamic range;
an input voltage scaling network including an array of parallel-connected sampling capacitors in an input amplifier providing a sampled input voltage to the ADC, such that the input voltage is sampled onto one or more selected sampling capacitors to scale the input voltage to substantially match the characteristic dynamic range of the ADC;
a network of high voltage sampling switches interposed between the input voltage and the input voltage scaling network, such that the input voltage is selectively sampled onto one or more of the sampling capacitors;
range decoder logic that controls the network of high voltage sampling switches to select said one or more of the sampling capacitors; and
a range register to which a range selection control word is written, the range decoder logic being responsive to the range selection control word. - View Dependent Claims (29, 30, 31, 32, 33, 34)
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35. A programmable input voltage range analog-to-digital converter integrated circuit device fabricated on a single substrate, the device comprising:
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an analog-to-digital converter (ADC) subsystem fabricated utilizing a standard sub-micron low-voltage CMOS process, and having a characteristic dynamic range;
an input voltage scaling network in which the input voltage is sampled onto one or more selected sampling capacitors to scale the input voltage to substantially match the characteristic dynamic range of the ADC; and
a network of high-voltage MOS sampling switches fabricated utilizing a split gate oxide process to accommodate higher gate voltages, said network of high-voltage sampling switches interposed between the input voltage and the input voltage scaling network, such that the input voltage is selectively sampled onto one or more of the sampling capacitors. - View Dependent Claims (36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47)
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48. A programmable input voltage range analog-to-digital converter integrated circuit device fabricated on a single substrate, the device comprising:
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an analog-to-digital converter (ADC) subsystem fabricated utilizing a standard sub-micron low-voltage CMOS process, and having a characteristic dynamic range;
an input voltage scaling network in which the input voltage is sampled onto one or more selected sampling capacitors to scale the input voltage to substantially match the characteristic dynamic range of the ADC;
a network of high-voltage MOS sampling switches fabricated utilizing a split gate oxide process to accommodate higher gate voltages, said network of high-voltage sampling switches interposed between the input voltage and the input voltage scaling network, such that the input voltage is selectively sampled onto one or more of the sampling capacitors;
range decoder logic that controls the network of high voltage MOS sampling switches to select said one or more of the sampling capacitors; and
a range register to which a range selection control word is written, the range decoder logic being responsive to the range selection control word. - View Dependent Claims (49, 50, 51, 52, 53, 54, 55)
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Specification