Converter arrangement and method for converting an analogue input signal into a digital output signal

1. A converter arrangement for converting an analog input signal y A into a digital output signal y D , the converter arrangement comprising

a first input terminal for receiving the analog input signal y A ,

a first analog source, which is configured and arranged to generate based on first control information P P ,1 a first perturbation signal s 1 such that said perturbation signal s 1 is incoherent to said analog input signal y A ;

a first linking device, which is configured and arranged to generate based on the first perturbation signal s 1 and the analog input signal y A a perturbed input signal y′ A ;

a first ADC having a nonlinear transfer function and which is configured and arranged to generate based on said perturbed input signal y′ A an ADC output signal y′ D , whereas the ADC output signal y′ D contains nonlinear ADC distortions n AD produced by the nonlinearity of the ADC;

a reference signal generator which is arranged and configured to generate a reference signal y R , which is incoherent with said first perturbation signal s 1 and which contains signal components that are coherent with the analog input signal y A ;

a parameter estimator, which is configured and arranged to generate based on said ADC output signal y′ D and said reference signal yR, said first control information P P,1 and an ADC parameter vector P AD , whereas parameter vector P AD describes the nonlinear transfer characteristic of the first ADC; and

an AD compensation element, which is configured and arranged to generate based on said ADC parameter vector P AD and said ADC output signal y′ D a digital output signal y D such that the nonlinear ADC distortions n AD of the ADC are reduced in said digital output signal y D. ; and

a first output terminal for providing the digital output signal y D .

2. The arrangement of claim 1 , where the AD compensation element contains a nonlinear transfer element, which is configured and arranged to generate based on said ADC output signal y′ D and said ADC parameter vector P AD a nonlinear compensation signal c AD such that the nonlinear compensation signal c AD compensates for said nonlinear ADC distortions n AD of the ADC; and

a second linking device, which is configured and arranged to generate based on said ADC output signal y′ D and said nonlinear compensation signal c AD a linearized output signal y c. .

3. The arrangement of claim 1 , wherein

said first analog source contains a first DAC, which is configured and arranged to generate based on a digital perturbation signal s D,1 an DAC output signal s A,1 ; and

said first analog source further contains a linear transfer element, which linear transfer element comprises a transfer function H G,1 (f) that is changed by said first control information P P,1 wherein said first control information P P,1 contains a digital perturbation signal s D,1 ; and which linear transfer element is configured and arranged to generate based on said DAC output signal s A,1 a first perturbation signal s 1 .

4. The arrangement of claim 3 , wherein

said AD compensation element contains at least one linear transfer element, which is configured and arranged to generate based on said first control information P P,1 a filtered perturbation signal s′ D,1 , wherein said transfer element models the transfer characteristics of the first analog source and the first ADC; and

said AD compensation element contains a third linking device, which is configured and arranged to generate based on said filtered perturbation signal s′ D,1 and said linearized output signal y c a digital output signal y D such that said first perturbation signal s 1 is reduced.

5. The arrangement of claim 1 , comprising

a digital signal generator for generating a DAC input signal x′ D ;

a DAC converting the DAC input signal x′ D into an DAC output signal x′ A ;

a second analog source, which is configured and arranged to generate based on second control information P P,2 a second perturbation signal s 2 such that said second perturbation signal s 2 is incoherent to said DAC output signal x′ A ;

a fourth linking device, which is configured and arranged to generate based on said second perturbation signal s 2 and said DAC output signal x′ A an analog output signal x A ; and

an interface for connecting a device under test to the converter arrangement, wherein in a test/operation mode where the device under test is connected to the converter arrangement the device under test converts said analog output signal x A into said analog input signal y A .

6. The arrangement of claim 5 , wherein

said DAC is configured to generate nonlinear distortion n DA,0 in said DAC output signal x′ A ;

said digital signal generator contains a digital signal source for generating an digital input signal x D with predefined properties; and

said digital signal generator contains a compensation element, which is configured and arranged to generate based on said digital input signal x D and said DAC parameter vector P DA a DAC input signal x′ D such that the nonlinear DAC distortions n DA,0 of said DAC are compensated.

7. The arrangement of claim 1 , wherein

the parameter estimator contains at least one of the following:

a digital signal source, which is configured and arranged to generate a filtered perturbation signal s′ D,i , which is coherent with the first perturbation signal s 1 of said first analog source;

an adder, which generates the sum signal y t by adding said reference signal y R and said filtered perturbation signal s′ D,i ;

a nonlinear ADC model, which is configured and arranged to generate based on said sum signal y t and said ADC parameter vector P AD a model output signal y M , which models the ADC output signal y′ D ;

an error assessing element generating based on said model output signal y M and said ADC output signal y′ D an error signal e, which describes the deviation between the nonlinear ADC model and the ADC;

a gradient device, which is configured and arranged to generate based on said reference signal y′ R and said filtered perturbation signal s′ D,i , a gradient signal g 2 AD , wherein said gradient signal g 2 AD contains intermodulation distortion generated by the multiplication of said reference signal y′ R and said filtered perturbation signal s′ D,i ; and

an estimator, which is configured and arranged to generate based on the gradient signal g 2 AD said ADC parameter vector P AD by minimizing the error signal e.

8. The arrangement of claim 5 , wherein

the ADC output signal y′ D is used as the reference signal y R ; or

the DAC input signal x′ D is used as the reference signal y R ; or

further comprising a reference ADC, which is configured and arranged to generate based on analog input signal y A the reference signal y R .

9. Measuring device comprising at least one a converter arrangement for converting an analog input signal y A into a digital output signal y D , the converter arrangement comprising

a first input terminal for receiving the analog input signal y A ,

a first analog source, which is configured and arranged to generate based on first control information P P,1 a first perturbation signal s 1 such that said perturbation signal s 1 is incoherent to said analog input signal y A ;

a first linking device, which is configured and arranged to generate based on the first perturbation signal s 1 and the analog input signal y A a perturbed input signal y′ A ;

a first ADC having a nonlinear transfer function and which is configured and arranged to generate based on said perturbed input signal y′ A an ADC output signal y′ D , whereas the ADC output signal y′ D contains nonlinear ADC distortions n AD produced by the nonlinearity of the ADC;

a reference signal generator is arranged and configured to generate a reference signal y R , which is incoherent with said first perturbation signal s 1 and which contains signal components that are coherent with the analog input signal y A ;

a parameter estimator, which is configured and arranged to generate based on said ADC output signal y′ D and said reference signal y R said first control information P P,1 and an ADC parameter vector P AD , whereas the parameter vector P AD describes the nonlinear transfer characteristic of the first ADC; and

an AD compensation element, which is configured and arranged to generate based on said ADC parameter vector P AD and said ADC output signal y′ D a digital output signal y D such that the nonlinear ADC distortions n AD of the ADC are reduced in said digital output signal y D .

a first output terminal for providing the digital output signal y D .

10. A method for converting an analog input signal y A into a digital output signal y D , the method comprising:

providing an analog input signal y A ;

providing a nonlinear ADC;

generating first control information P P,1 based on said analog input signal y A ;

generating a first perturbation signal s 1 based on said first control information P P,1 such that the first perturbation signal s 1 is incoherent to the analog input signal y A ;

generating a perturbed input signal y′ A based on said first perturbation signal s 1 and said analog input signal y A ;

converting said perturbed input signal y′ A into an ADC output signal y′ D such that said ADC output signal y′ D contains nonlinear ADC distortions n AD produced by a nonlinearity of the ADC;

providing a reference signal y R , which is incoherent with the first perturbation signal s 1 and which is coherent with the analog input y A ;

generating an ADC parameter vector P AD and said first control information P P,1 based on said ADC output signal y′ D and said reference signal y R such that said ADC parameter vector P AD describes the generation of the nonlinear ADC distortions n AD in the ADC; and

generating an digital output signal y D based on said ADC output signal y′ D and said ADC parameter vector P AD such that said nonlinear ADC distortions n AD are reduced in the output signal y D .

11. The method of claim 10 , wherein generating said digital output signal y D contains at least one of:

generating a nonlinear compensation signal c AD based on said ADC output signal y′ D and said ADC parameter vector P AD such that said nonlinear compensation signal c AD compensates for said nonlinear ADC distortions n AD of the ADC; and

generating a linearized output signal y c based on said ADC output signal y′ D and said nonlinear compensation signal c AD .

12. The method of claim 10 , wherein generating said first perturbation signal s 1 contains at least one of:

generating a digital perturbation signal s D,1 in said first control information P P,1 ;

converting said digital perturbation signal s D,1 into an analog DAC output signal s A,1 ; and

generating a first perturbation signal s 1 by linear filtering said DAC output signal s A,1 with the transfer function H G,1 (f) defined by said first control information P P,1 .

13. The method of claim 12 , wherein generating said digital output signal y D contains at least one of:

generating a filtered perturbation signal s′ D,1 by filtering said digital perturbation signal s D,1 with a linear transfer function, which describes the transfer of the digital perturbation signal s D,1 to said ADC output signal y′ D ; and

generating a digital output signal y D by combining said filtered perturbation signal s′ D,1 with said linearized output signal y c , wherein said filtered perturbation signal s′ D,1 compensates for said first perturbation signal s 1 .

14. The method of claim 10 , further comprising at least one of:

generating a DAC input signal x′ D ;

converting said DAC input signal x′ D into an DAC output signal x′ A ;

generating an analog output signal x A based on said DAC output signal x′ A ;

supplying said analog output signal x A to an input of a device under test; and

generating said analog input signal y A by measuring a state variable of the device under test.

15. The method of claim 14 , where generating said analog output signal x A contains at least one of:

generating a second perturbation signal s 2 based on said second control information P P,2 , wherein said second perturbation signal s 2 is incoherent to said DAC output signal x′ A ; and

generating said analogue output signal x A by combining said second perturbation signal s 2 with the DAC output signal x′ A .

16. The method of claim 14 , wherein generation of said DAC input signal x′ D contains at least one of:

providing a digital input signal x D ;

generating a DAC compensation signal c DA based on said digital input signal X D by

using said DAC parameter vector P DA , wherein said DAC compensation signal c DA models said nonlinear DAC distortions n DA,0 generated by converting said DAC input signal x′ D into an DAC output signal x′ A ;

generating a DAC input signal x′ D based on said DAC compensation signal c DA and said digital signal X D , wherein said DAC compensation signal c DA compensates said nonlinear DAC distortions n DA,0 generated in said DAC output signal x′ A .

17. The method of claim 10 , wherein generating an ADC parameter vector P AD contains at least one of:

generating a filtered perturbation signal s′ D,1 based on said digital perturbation signal s D,1 , wherein said filtered perturbation signal s′ D,1 is coherent with the first perturbation signal s 1 ;

generating a sum signal y t based on said reference signal y R and said filtered perturbation signal s′ D,1 ;

generating a model output signal y M approximating said ADC output signal y′ D based on said sum signal y t and said ADC parameter vector P AD ;

generating an error signal e based on said model output signal y M and said ADC output signal y′D, wherein said error signal e describes the deviation of the model output signal yM from the ADC output signal y′ D ;

generating a gradient signal g 2 AD based on said reference signal y R and said filtered perturbation signal s′ D,1 , wherein the gradient signal g 2 AD contains nonlinear intermodulation distortion generated by said reference signal −y R and said filtered perturbation signal s′ D,1 ; and

estimating the ADC parameter vector P AD based on said gradient signal g 2 AD by minimizing the error signal e.

18. The method of claim 14 , further comprising:

generating said reference signal y R based on said ADC output signal y′ D or based on said DAC input signal x′ D or based said analog input signal y A .