Parallel processing for programmable wideband digital modulation
View Patent ↗A circuit 30 for upsampling and upconverting a high rate signal that is divided into M in-phase (I) symbols and M quadrature (Q) symbols. A Nyquist filter 32 upsamples by a factor of k each of the 2M symbols in parallel during one system clock period (CP). The filter 32 has a plurality of 2kM filter components 40, 42 , that each provides a continuous output. A plurality of multipliers 50, 52 each upconverts a filter component output with a carrier wave signal 46, 48 that is output from a numerically controlled oscillator 44 . A plurality of adders 54 each adds the output of two multipliers 50 to recombine corresponding I and Q samples to output kM samples during a CP. For continuous phase modulation, N parallel bits are input into the filter 32 , upsampled in one CP, and accumulated and modulated 82 in parallel in one CP. For analog processing, M (I) and M (Q) symbols are input into an FIR filter 77 a, 77 b for upsampling, and decimated at a MUX/DAC block 78 for subsequent analog upconversion.
1. A circuit for upsampling a high rate data stream comprising:
a system clock defining a clock period;
an upsampling pulse shaping filter for converting N bits input in parallel thereto during one clock period to an output of kN samples that are output in parallel during one clock period, wherein k is an integer greater than one;
an accumulator block having an input coupled to the output of the filter; and
a modulation block, having an input coupled to the output of the filter, for modulating the samples according to a continuous phase modulation technique and for outputting the modulated samples on kN parallel in-phase streams and on kN parallel quadrature streams.
2. A method for digitally sampling and modulating a high rate data stream comprising:
dividing a high rate data stream into N bits, wherein N is an integer greater than one;
upsampling each of the bits by a factor of k in parallel during a single clock period to provide a continuous output that includes the samples;
upconverting and modulating at least some of the samples by accumulating and modulating the samples according to a continuous phase modulation technique to output kN phase components that are then converted to kN in-phase and kN quadrature outputs for upconversion.
3. The method of claim 2 wherein upsampling is by the polyphase Nyquist filter and upconverting occurs on all samples using a numerically controlled oscillator.
4. The method of claim 2 wherein upsampling is by the FIR filter, and wherein upconverting and modulating comprises decimating, multiplexing, and converting to analog less than all samples, outputting analog samples that are in-phase and quadrature versions of a converted sample, and upconverting the analog samples.