Analog to digital ramp converter
First Claim
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1. A method of analog to digital voltage conversion comprising:
- generating a quadratic signal based on an analog time varying reference signal;
generating a ramp signal based on said quadratic signal, wherein generating said ramp signal further comprises generating a linear signal and summing said linear and quadratic signals to generate said ramp signal, and wherein said quadratic signal is offset by a reference time with respect to said linear signal such that said ramp signal comprises a linear portion up to said reference time; and
converting an analog input voltage to a digital output value based on a time duration determined by a comparison of said analog input voltage with said ramp signal.
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Abstract
A method of analog to digital voltage conversion including: generating a quadratic signal based on an analog time varying reference signal; generating a ramp signal based on the quadratic signal; and converting an analog input voltage to a digital output value based on a time duration determined by a comparison of the analog input voltage with the ramp signal.
22 Citations
27 Claims
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1. A method of analog to digital voltage conversion comprising:
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generating a quadratic signal based on an analog time varying reference signal; generating a ramp signal based on said quadratic signal, wherein generating said ramp signal further comprises generating a linear signal and summing said linear and quadratic signals to generate said ramp signal, and wherein said quadratic signal is offset by a reference time with respect to said linear signal such that said ramp signal comprises a linear portion up to said reference time; and converting an analog input voltage to a digital output value based on a time duration determined by a comparison of said analog input voltage with said ramp signal. - View Dependent Claims (2, 3, 4, 5, 7, 8)
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6. A method of analog to digital voltage conversion comprising:
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generating a quadratic signal based on an analog time varying reference signal; generating a ramp signal based on said quadratic signal, and converting an analog input voltage to a digital output value based on a time duration determined by a comparison of said analog input voltage with said ramp signal, wherein said converting step comprises starting an N-bit counter at a start of said ramp signal, and storing the N-bit value of said counter when a voltage level of said ramp signal corresponds to the level of said analog input voltage, wherein said counter increments in a linear manner, the method further comprising linearizing said digital output value by converting it into an M-bit value, wherein M is equal to at least N+1.
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9. An analog to digital converter comprising:
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a ramp generator adapted to generate; a quadratic signal based on an analog time varying reference signal; and a ramp signal based on said quadratic signal, wherein said ramp generator comprises a first digital to analog converter arranged to generate said quadratic signal by converting a digital time signal into said quadratic signal based on an analog time varying reference signal, wherein said quadratic signal and said analog time varying reference signal are currents, and wherein said ramp generator further comprises a second digital to analog converter arranged to convert said digital time signal into said time varying reference signal based on a reference current; and circuitry adapted to convert an analog input voltage to a digital output value based on a time duration determined by a comparison of said analog input voltage with said ramp signal. - View Dependent Claims (10, 12)
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11. An analog to digital converter comprising:
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a ramp generator adapted to generate; a quadratic signal based on an analog time varying reference signal; and a ramp signal based on said quadratic signal; and circuitry adapted to convert an analog input voltage to a digital output value based on a time duration determined by a comparison of said analog input voltage with said ramp signal, wherein said digital output value is an N-bit value, and further comprising adjustment circuitry adapted to convert said N-bit digital output value into an M-bit value based on a lookup table, wherein M is equal to at least N+1.
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13. A method for analog to digital conversion, comprising:
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generating a ramp signal that includes a quadratic signal and a linear signal, wherein generating the ramp signal comprises summing the quadratic signal and the linear signal; converting an analog input voltage to an N-bit value, including comparing the analog input voltage to the ramp signal and controlling storage of the N-bit value based on the comparison; and converting the N-bit value to a linearized digital output value. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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22. An analog to digital converter comprising:
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a ramp generator configured to generate a ramp signal that includes a quadratic signal and a linear signal, wherein the ramp generator is configured to start the quadratic signal after a reference time with respect to the linear signal, such that the ramp signal is linear until the reference time has elapsed; a conversion circuit configured to convert an analog input voltage to an N-bit value, the conversion circuit including a comparison circuit configured to compare the analog input voltage to the ramp signal and to control storage of the N-bit value based on the comparison; and an adjustment circuit configured to convert the N-bit value to a linearized digital output value. - View Dependent Claims (23, 24, 25, 26, 27)
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Specification