Method and apparatus for analyzing an analog-to-digital converter with a nonideal digital-to-analog converter

Claim 1

A method for calibrating an analog-to-digital converter (ADC) comprising the steps of: exciting a plurality of inputs of a digital-to-analog converter (DAC) from an excitation means generating known digital excitation signals, each said excitation signal being applied at a single digital bit input of the DAC and each said excitation signal being binary and orthogonal with respect to all other ones of said plurality of excitation signals, the sum of said excitation signals constituting a maximum entropy sequence of substantially uniform amplitude probability, said DAC producing an analog output signal, the transfer function of said DAC having been characterized by premeasured bit weighting values; providing said analog output signal of the DAC to an analog input of the analog-to-digital converter (ADC) under test, said ADC producing digital output signals; transforming said digital output signals from time domain digital signals into binary transform domain digital signals to obtain an output response weighting coefficient for each bit of the converter under test; and correcting each said output response weighting coefficient for bias errors induced by said DAC by adding to each output response weighting coefficient the corresponding difference between the ideal binary weights and said premeasured bit weighting values in a bias correction means in order to obtain unbiased weighting values of each bit specifying the transfer characteristic of the ADC under test.

Claim 2

A method for calibrating an analog-to-digital converter (ADC) comprising the steps of: exciting a plurality of inputs of a digital-to-analog converter (DAC) from an excitation means generating known digital excitation signals, each said excitation signal being applied at a single digital bit input of the DAC and each said excitation signal being binary and orthogonal with respect to all other ones of said plurality of excitation signals, the sum of said excitation signals constituting a maximum entropy sequence of substantially uniform amplitude probability, said DAC producing an analog output signal, the transfer function of said DAC having been characterized by premeasured bit weighting values; providing said analog output signal of the DAC to an analog input of the analog-to-digital converter (ADC) under test, said ADC producing digital output signals; transforming said digital output signals from time domain digital signals into binary transform domain digital signals to obtain an output response weighting coefficient for each bit of the converter under test; and correcting each said output response weighting coefficient for bias errors induced by said DAC by adding to each output response weighting coefficient the corresponding difference between the ideal binary weights and said premeasured bit weighting values in a bias correction means in order to obtain unbiased weighting values of each bit specifying the transfer characteristic of the ADC under test.

Claim 7

An apparatus for calibrating an analog-to-digital converter (ADC) comprising: means for exciting inputs of a digital-to-analog converter (DAC) from an excitation means operative to generate known digital excitation signals at selected digital excitation signal outputs, each said excitation signal output being adapted to be coupled to a single digital bit input of the DAC under test and each said excitation signal constituting a maximum entropy sequence of substantially uniform amplitude probability, said DAC producing an analog output signal at an analog output signal terminal, the transfer function of said DAC having been characterized by premeasured weighting values of a set of binary orthogonal functions; the ADC under test adapted to be coupled to said DAC analog output signal terminal, said ADC under test being operative to produce digital output signals in response to said analog output signal; means for transforming said digital output signals from time domain digital signals into binary transform domain digital signals to obtain an output response weighting coefficient for each bit of the converter under test; and means for correcting each said output response weighting coefficient for bias errors induced by said DAC by adding to each output response weighting coefficient the corresponding difference between the ideal binary weights and said premeasured weighting values in order to obtain unbiased weighting values of each bit specifying the transfer characteristic of the analog-to-digital converter under test.

Claim 8

An apparatus for calibrating an analog-to-digital converter (ADC) comprising: means for exciting inputs of a digital-to-analog converter (DAC) from an excitation means operative to generate known digital excitation signals at selected digital excitation signal outputs, each said excitation signal output being adapted to be coupled to a single digital bit input of the DAC under test and each said excitation signal constituting a maximum entropy sequence of substantially uniform amplitude probability, said DAC producing an analog output signal at an analog output signal terminal, the transfer function of said DAC having been characterized by premeasured weighting values of a set of binary orthogonal functions; the ADC under test adapted to be coupled to said DAC analog output signal terminal, said ADC under test being operative to produce digital output signals in response to said analog output signal; means for transforming said digital output signals from time domain digital signals into binary transform domain digital signals to obtain an output response weighting coefficient for each bit of the converter under test; and means for correcting each said output response weighting coefficient for bias errors induced by said DAC by adding to each output response weighting coefficient the corresponding difference between the ideal binary weights and said premeasured weighting values in order to obtain unbiased weighting values of each bit specifying the transfer characteristic of the analog-to-digital converter under test.