Inter-stage gain calibration in double conversion analog-to-digital converter
First Claim
1. A method of estimating a residue gain in an analog-to-digital converter (ADC) circuit having a residue gain amplifier coupled to a digital-to-analog converter (DAC) circuit, the method comprising:
- generating a first residue voltage of a sample of an analog input signal with respect to a first code applied to at least one reference element coupled to the DAC;
amplifying the first residue voltage using the residue gain amplifier to provide a first amplified residue voltage;
generating a second residue voltage of the sample of the analog input signal with respect to a second code applied to the at least one reference element coupled to the DAC;
amplifying the second residue voltage using the residue gain amplifier to provide a second amplified residue voltage; and
comparing the first and second amplified residue voltages to a difference between the first and second codes applied to the at least one reference element coupled to the DAC to determine information about the residue gain of the residue gain amplifier.
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Accused Products
Abstract
Various background calibration techniques to calibrate inter-stage gain, e.g., in pipelined ADCs, are described to allow open loop amplifier circuits to be used as residue amplifiers for better power efficiency. Using various techniques, a well-controlled perturbation can be injected between two conversions and the actual perturbation after a residue amplifier can be measured. By comparing the actual measurement against an expected value, the gain information of the residue amplifier can be estimated and then calibration can be applied.
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Citations
26 Claims
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1. A method of estimating a residue gain in an analog-to-digital converter (ADC) circuit having a residue gain amplifier coupled to a digital-to-analog converter (DAC) circuit, the method comprising:
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generating a first residue voltage of a sample of an analog input signal with respect to a first code applied to at least one reference element coupled to the DAC; amplifying the first residue voltage using the residue gain amplifier to provide a first amplified residue voltage; generating a second residue voltage of the sample of the analog input signal with respect to a second code applied to the at least one reference element coupled to the DAC; amplifying the second residue voltage using the residue gain amplifier to provide a second amplified residue voltage; and comparing the first and second amplified residue voltages to a difference between the first and second codes applied to the at least one reference element coupled to the DAC to determine information about the residue gain of the residue gain amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 21, 22)
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11. An analog-to-digital converter (ADC) circuit for estimating a residue gain of a residue gain amplifier coupled to an output of a digital-to-analog converter (DAC) circuit, the ADC circuit comprising:
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at least one reference element coupled to the input of the residue gain amplifier; a control circuit configured to control application of first and second codes to the at least one reference element to generate corresponding first and second residue voltages of a sample of an analog input signal, the first and second residue voltages amplified by the residue gain amplifier to generate first and second amplified residue voltages; and a back-end circuit coupled to an output of the residue gain amplifier, the back-end circuit configured to compare the first and second amplified residue voltages to a difference between the first and second codes applied to the at least one reference element to determine information about the residue gain of the residue gain amplifier. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 23, 24)
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19. An analog-to-digital converter (ADC) circuit for estimating a residue gain of a residue gain amplifier coupled to an output of a digital-to-analog converter (DAC) circuit, the ADC circuit comprising:
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means for generating a first residue voltage of a sample of an analog input signal with respect to a first code applied to at least one reference element coupled to the DAC; means for amplifying the first residue voltage using the residue gain amplifier to provide a first amplified residue voltage; means for generating a second residue voltage of the sample of the analog input signal with respect to a second code applied to the at least one reference element coupled to the DAC; means for amplifying the second residue voltage using the residue gain amplifier to provide a second amplified residue voltage; and means for comparing the first and second amplified residue voltages to a difference between the first and second codes applied to the at least one reference element coupled to the DAC to determine information about the residue gain of the residue gain amplifier. - View Dependent Claims (20, 25, 26)
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Specification