Acquisition device with multistage digital equalization

摘要

An acquisition device includes an analog to digital converter (ADC) composed of multiple interleaved ADCs (sub-ADCs), which receives an analog signal which is converted to digital form. The digitized signal is processed seriatim by a pre-(or trigger-) equalizer, an acquisition memory and a post-(or memory) equalizer. In a calibration mode, frequency responses of the respective sub-ADCs are determined and trigger coefficients are determined for application to the trigger equalizer to effect a preliminary equalization of the digitized signal sufficient to permit operation of the trigger processor in an acquisition mode. Memory coefficients are determined based on residual frequency responses of the sub-ADCs, for application to the memory equalizer. A trigger processor is responsive to the trigger equalizer to select a subset of samples of the digitized signal for loading to the acquisition memory. The trigger equalizer and a memory equalizer are configured for consecutive operation so that, in an acquisition mode, the memory equalizer receives as its input, a digitized signal from the ADC that has been pre-processed in the trigger equalizer, and the memory equalizer corrects only the residue of misalignments and frequency distortions that remain after the trigger equalizer operation.

主权项

1. An acquisition device for multistage digital equalization comprising;
A. a composite analog to digital converter (ADC) including a plurality of interleaved sub-ADCs, the ADC having an analog input common to the sub-ADCs, wherein each sub-ADC has an associated sub-ADC output, and wherein each sub-ADC is characterized by an associated frequency response, each sub-ADC being responsive to an analog signal at the analog input, to generate at its associated sub-ADC output, a sequence of digital samples weighted by the associated frequency response of the sub-ADC and otherwise corresponding to instantaneous values of the analog signal at the analog input at a system sampling rate;
wherein the frequency responses of the respective sub-ADCs are characterized by mutual misalignments from sub-ADC to sub-ADC, and a composite frequency response of the composite analog to digital converter as a whole is characterized by frequency response distortion; B. a frequency responses measurer having measurer inputs connected to the respective sub-ADC outputs, and measurements outputs, the measurer being responsive to the respective sub-ADC outputs to measure the frequency responses of the respective sub-ADCs and to generate at the respective measurements outputs, measurement signals representative of the frequency responses of the respective sub-ADCs; C. a pre-equalizer coefficients calculator having pre-equalizer coefficients inputs connected to the respective measurer outputs, and pre-equalizer coefficients outputs wherein the pre-equalizer coefficients calculator is responsive to the measurer outputs to generate pre-equalizer coefficients at the pre-equalizer coefficients outputs;
wherein the pro-equalizer coefficients are determined for effecting partial reduction of misalignments of the respective sub-ADC outputs and partial reduction of frequency response distortion associated with the composite analog to digital converter as a whole; and D. a pre-equalizer having pre-equalizer inputs connected to the respective sub-ADC outputs of the composite analog to digital converter, pre-equalizer coefficients inputs for receiving the pre-equalizer coefficients from the pro-equalizer coefficient outputs of the pre-equalizer coefficients calculator, and pre-equalizer outputs, wherein the pre-equalizer is responsive to the respective sub-ADC outputs and the pre-equalizer coefficients, to generate at the pre-equalizer outputs, pre-equalized signals including components corresponding to the respective sub-ADC outputs wherein the components are characterized by the partial reduced misalignments with respect to the respective sub-ADC outputs, and the partial reduced frequency response distortion relative the frequency response distortion associated with the composite analog to digital converter as a whole.