Interleaved analog to digital converter with reduced number of multipliers for digital equalization

An interleaved analog to digital converter with digital equalization, comprising:

• A. a composite ADC including M time interleaved sub-ADCs and having a composite ADC input for receiving an input analog signal, and adapted for generating a corresponding stream of digital sample signals at a composite ADC output;
• B. a demultiplexer having an demux input coupled to the composite ADC output, and adapted to split the stream of digital sample signals into N sub streams with each sub stream characterized by a samples rate reduced by a factor N, and each sub stream being applied to a respective one of N demux outputs;
• C. a samples repositioning unit having N-group inputs coupled to respective ones of said N demux outputs, N-group leading outputs and N-group lagging outputs, and adapted for
• i. transposing digital sample signals by collecting for each N-group, samples that were produced by the same sub-ADC,
• ii. producing two streams of repositioned N-groups of the transposed digital sample signals, including lagging N-groups and leading N-groups, wherein digital sample signals in leading N-group are ahead of digital sample signals in corresponding lagging N-groups by an interval of (N−1)M,
• iii. applying the lagging N-groups to respective ones of the N-group lagging outputs, and
• iv. applying the leading N-groups to respective ones of the N-group leading outputs,
• D. a first PreFIRs transformer having N first PreFIRs inputs and K first PreFIRs outputs, and a second PreFIRs transformer having N second PreFIRs inputs and K second PreFIRs outputs,
• wherein the inputs of the first PreFIRs transformer are connected to respective ones of the N N-group leading outputs, and the first PreFIRs transformer is adapted to iteratively process the leading N-group digital sample signals to generate leading FIR input digital sample signals and apply the so-processed signals to respective ones of the K first PreFIRs outputs, and
• wherein the inputs of the second PreFIRs transformer are connected to respective ones of the N-group lagging outputs, and the second PreFIRs transformer is adapted to iteratively process the lagging N-group digital sample signals to generate lagging FIR input digital sample signals and apply the so-processed signals to respective ones of the K second PreFIRs outputs,
• E. K double buffer FIR filters, each double buffer FIR filter having K leading FIR inputs, K lagging FIR inputs and K FIR filter outputs, wherein the K leading FIR inputs of the double buffer FIR filter are connected to corresponding outputs of the first PreFIRs transformer and the K lagging FIR inputs of the double buffer FIR filter are connected to corresponding outputs of the second PreFIRs transformer, and wherein the K double buffer FIR filters effect K coefficient-weighted combinations of the processed leading N-group digital sample signals applied from the first PreFIRs transformer and the processed lagging N-group digital sample signals applied from the second PreFIRs transformer, and apply those K coefficient-weighted combinations to respective ones of the K FIR filter outputs;
• F. a PostFIRs transformer with K PostFIRs inputs and N PostFIRs outputs, wherein each of the K PostFIRs inputs is connected to the output of a corresponding double buffer FIR filter, and wherein each PostFIRs transformer is adapted iteratively process the applied K coefficient-weighted combinations and apply the so-processed coefficient-weighted combinations to respective ones of the N PostFIRs outputs,
• G. a samples sequence restoration unit having N repositioned N-group inputs connected to respective ones of the N PostFIRs outputs, and N-group outputs, wherein the samples sequence restoration unit is adapted for generating a restored sample stream comprising restored N sub stream samples, wherein the order of samples is restored to an initial order, and applying the restored sample stream to the respective N-group outputs;
• and
• H. a multiplexer having N mux inputs connected to the N-group outputs of the samples sequence restoration unit, and an equalizer output, and wherein the multiplexer is adapted for combining the restored N sub stream samples from the samples sequence restoration unit into one output samples stream applied to the equalizer output.