Mixed-Mode Millimeter-Wave Transmitter for Low-Noise Multiband RF
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current multi-band radio frequency transmitters face challenges in efficiently transmitting contiguous and non-contiguous signals due to out-of-band noise and stringent sampling rate requirements, particularly when designing for high-frequency millimeter-wave operations like 5G, which limits their flexibility and performance.
Innovation Solution
A mixed-mode transmitter architecture that parallelizes and serializes multi-band signals, allowing for reduced sampling rates and effective frequency re-configurability by placing digital up-conversion before pulse encoding, and incorporating analog components to support higher frequencies, thereby reducing complexity and improving signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If digital up-conversion is placed after pulse encoding to achieve multi-band transmission, then multi-band capability is enabled, but out-of-band noise is degraded and system performance deteriorates
Solution Approach 1:
The patent inverts the conventional order of operations by placing digital up-conversion before pulse encoding instead of after. This reversal allows the up-conversion to occur on the baseband signal at lower frequencies, avoiding the generation of excessive out-of-band noise that would occur if up-conversion were performed after encoding on already-modulated signals. The inversion resolves the contradiction by maintaining multi-band capability while preserving signal quality.
2Measurement precision
If digital up-conversion is placed before pulse encoding to reduce out-of-band noise, then signal quality improves, but sampling rate requirements increase significantly
Solution Approach 1:
The patent segments the up-conversion process into multiple stages: first performing up-conversion to an intermediate frequency, then performing pulse encoding, and finally performing a second up-conversion to the target RF band. This segmentation allows each stage to operate at manageable sampling rates rather than requiring a single high-speed stage to handle the entire frequency translation, thus resolving the contradiction between signal quality and sampling rate requirements.
Solution Approach 2:
The patent introduces an intermediate frequency stage as a mediator between the baseband and the final RF band. This intermediate stage allows the signal to be up-converted in two steps rather than one, enabling the use of lower sampling rates at each stage while still achieving the desired high-frequency output, thereby resolving the contradiction between improved signal quality and reduced sampling rate requirements.
3Reliability
If high sampling rates are used to support multi-band transmission, then transmission quality is maintained, but device complexity and cost increase
Solution Approach 1:
The patent segments the frequency translation into multiple lower-speed stages rather than requiring a single high-speed operation. By dividing the up-conversion process into intermediate steps, the system maintains transmission quality through proper signal processing while avoiding the need for extremely high sampling rates that would increase device complexity and cost.
4Speed
If analog components are used to support millimeter-wave frequencies, then high-frequency operation is enabled, but device complexity increases
Solution Approach 1:
The patent performs preliminary digital signal processing and up-conversion to higher frequencies before the signal reaches the analog front-end. This preliminary action in the digital domain reduces the burden on the analog components, allowing them to operate at millimeter-wave frequencies with simpler architecture since much of the complex signal processing has already been completed digitally.
Data Source
AI summary
A radio frequency (RF) transmitter includes a set of input ports to receive baseband samples of a signal to be transmitted on a set of disjoint frequency bands, a set of filter banks, there is one filter bank for each input port, each filter bank includes a plurality of digital polyphase interpolation filters to sample a shifted phase of the corresponding sequence of baseband samples and to interpolate the sampled phases to produce a plurality of sequences of interpolated baseband phased samples with the shifted phase, and a set of oscillators banks, each oscillator bank includes a plurality of polyphase Digital Direct Synthesizer (DDS) corresponding to the plurality of digital polyphase interpolation filters to generate a plurality of sequences of samples of digital waveform. The RF transmitter includes a set of mixer banks to mix corresponding sequences of samples of digital waveform and interpolated baseband phased samples to up convert each sequence of interpolated baseband phased samples to the effective frequency, a parallel digital combiner to combine in-phase sequences of interpolated baseband phased samples of different frequency bands to produce a plurality of sequences of multiband upconverted samples, and a pulse encoder to modulate and encode the plurality of sequences of multiband upconverted samples to produce a plurality of encoded multi-band signals. The RF transmitter converts the plurality of encoded multi-band signals into a RF bitstream and radiate the RF bitstream as an analog signal.