Linear/companding A/D converter
AssigneeTexas Instruments Incorporated
InventorsHenry T. Yung, James R. Hochschild, William A. Severin
Life of this patent
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Abstract
A multi-mode analog to digital converter is described for converting an analog input into a digital value according to a linear or a companding transfer function. The converter comprises a comparator, a successive approximation register and a charge redistribution device. The comparator compares the input voltage and a generated voltage. The successive approximation register generates a provisional binary word responsive to the output of the comparator. The charge redistribution device generates the generated voltage according to the provisional binary word and to a selected transfer function. The transfer function may be selected from the group consisting of linear and companding.
Claims9
A multi-mode analog to digital converter comprising:
- a comparator for comparing an input voltage level and a generated voltage level;
- a successive approximation register for generating a provisional binary word responsive to the output of the comparator;
- control circuitry for selecting a transfer function, the transfer function selected from the group consisting of linear and companding;
- and
- a charge redistribution device for generating the generated voltage responsive to the provisional binary word and to the selected transfer function.
A multi-mode analog to digital converter comprising:
- a comparator for comparing an input voltage level and a generated voltage level;
- a successive approximation register for generating a provisional binary word responsive to the output of the comparator;
- a first array of capacitors for generating a first voltage level at a first node, a first terminal of each of the capacitors coupled to the first node;
- a second array of capacitors for generating the generated voltage at an output node, a first terminal of each of the capacitors coupled to the output node;
- a scaling capacitor having first and second terminals, the first terminal coupled to the first node and the second terminal coupled to an intermediate node;
- control circuitry for selecting a transfer function, the transfer function selected from the group consisting of linear and companding;
- and
- switching circuitry for selectively coupling ones of the first and second arrays of capacitors to voltages of first and second sets of voltages, respectively, the second set of voltages comprising the voltage at the intermediate node, the circuitry responsive to the selected transfer function.
A method for converting an analog voltage level to a digital word comprising the steps of:
- providing a signal to a control circuit for selecting a transfer function, the transfer function selected from the group consisting of linear and companding;
- generating a voltage level at a first node, the voltage level responsive to a provisional binary word and to the selected transfer function;
- comparing the generated voltage level to the analog voltage level with a comparator;
- and
- modifying the provisional binary word responsive to the output of the comparator.
Dependencies are inferred from the claim text.