Digital RF Bit Generator Architecture for Low-Noise Multi-Band Transmission
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Solution Overview
Problem
Current multi-band radio frequency transmitter designs face challenges in efficiently transmitting contiguous and non-contiguous signals due to out-of-band noise and stringent sampling rate requirements, leading to degraded system performance and increased complexity.
Innovation Solution
A parallel architecture for a digital RF transmitter that places digital up-converters before pulse encoders, utilizing polyphase interpolation filters and digital direct synthesizers to reduce sampling rates and enable multi-band parallelization, allowing for efficient transmission across multiple frequency bands with reduced out-of-band noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If digital up-converters are placed after pulse encoders, then the architecture follows conventional design, but out-of-band noise is distributed over the entire spectrum leading to degraded system performance
Solution Approach 1:
The patent inverts the conventional architecture by placing digital up-converters before pulse encoders instead of after. This inversion allows the up-converters to operate on baseband signals with lower sampling rates, and the pulse encoders to process already-upconverted signals, thereby concentrating out-of-band noise in specific frequency regions rather than distributing it across the entire spectrum, which improves system performance
2Productivity
If digital up-converters are placed before pulse encoders, then sampling rates can be reduced and multi-band parallelization is enabled, but the architecture becomes more complex
Solution Approach 1:
The patent segments the transmitter architecture into parallel processing paths for different frequency bands. Each band can be processed independently through its own digital up-converter and pulse encoder chain, allowing for reduced sampling rates in each path while enabling efficient multi-band transmission. This segmentation approach manages complexity by organizing functions into modular, reusable units
Solution Approach 2:
The patent designs universal building blocks (digital up-converters and pulse encoders) that can process multiple frequency bands. These components are configured to handle different bands through reconfigurable parameters rather than requiring dedicated hardware for each band, thereby reducing overall system complexity while maintaining multi-band capability
3Adaptability or versatility
If integer multiples of modulators sampling frequencies are used for multi-band transmission, then multi-band capability is achieved, but the span between bands is limited and performance is reduced
Solution Approach 1:
The patent changes the sampling rate parameter to be non-integer multiples of the modulator sampling frequency. This allows for larger frequency spans between bands while maintaining signal integrity. The digital up-converters are configured with flexible sampling rates that are not constrained to integer multiples, thereby improving the Signal-to-Noise Ratio while preserving multi-band capability
Data Source
AI summary
A radio frequency (RF) transmitter includes a set of input ports to receive baseband, a set of filter banks for each input port that includes a plurality of digital polyphase interpolation filters, and a set of oscillators banks, wherein each oscillator bank includes a plurality of polyphase Digital Direct Synthesizer (DDS) corresponding to the plurality of digital polyphase interpolation filters. The RF transmitter includes a set of mixer banks to mix corresponding sequences of samples of digital waveform, a parallel digital combiner to combine in-phase sequences of interpolated baseband phased samples, and a pulse encoder to modulate and encode the plurality of sequences of multiband upconverted samples. The RF transmitter converts a plurality of encoded multi-band signals into a RF bitstream and an E/O interface to convert the RF bitstream.