Single-Path RF Receiver for Carrier Aggregation and LO Interference
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Solution Overview
Problem
Current RF receivers face challenges in efficiently receiving multiple radio frequency bands due to high dynamic range and bandwidth requirements, leading to increased current consumption and silicon area, as well as interference between local oscillators in carrier aggregation scenarios.
Innovation Solution
The implementation of a single RF receiver path with a complex filter having a variable center frequency and a Finite Impulse Response (FIR) mixer for harmonic rejection, allowing simultaneous reception of multiple carriers with improved synchronization and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single receiver path is used to receive multiple frequency bands simultaneously, then the number of parallel receiver chains is reduced, but the bandwidth and dynamic range requirements increase leading to higher current consumption and silicon area
Solution Approach 1:
The patent segments the receiver functionality by separating the RF front-end into multiple independent receiver paths that share common components (RF input buffer, LO source). Each receiver path can be independently configured for different frequency bands, allowing selective activation based on carrier aggregation requirements, thus reducing overall power consumption compared to always-on parallel chains
Solution Approach 2:
The patent implements a universal receiver architecture where a single receiver path can handle multiple frequency bands through configurable filtering and mixing stages. The complex filter with variable center frequency and the shared LO source enable the same hardware to serve multiple functions across different bands, reducing the need for dedicated parallel receiver chains
2Device complexity
If a single receiver path is used to receive multiple frequency bands simultaneously, then the number of parallel receiver chains is reduced, but the bandwidth and dynamic range requirements increase leading to larger silicon area
Solution Approach 1:
The patent merges multiple receiver functions into a single shared receiver path by combining common components (RF input buffer, LO source, ADC) that serve multiple frequency bands. This consolidation reduces the total silicon area required compared to having separate dedicated receiver chains for each band, while still enabling simultaneous multi-band reception through configurable filtering and mixing
3Reliability
If two separate receivers are used for frequency bands close to each other, then each receiver can operate independently, but the generated LO-frequencies disturb each other causing interference
Solution Approach 1:
The patent introduces an intermediary approach by using a shared LO source with selective activation. Instead of having two independent LO generators that interfere with each other, a single LO source serves both receiver paths, but only the required path is activated at any given time. This eliminates LO interference while maintaining independent reception capability through controlled signal routing and filtering
4Object-generated harmful factors
If one oscillator is forced to operate at double or higher frequency to avoid interference, then LO interference is eliminated, but the frequency synthesizer and LO-divider implementation becomes more complex
Solution Approach 1:
Instead of forcing the oscillator to operate at higher frequencies to avoid interference, the patent inverts the approach by using selective activation of receiver paths. The LO operates at its fundamental frequency, and interference is avoided by ensuring only one receiver path is active at a time through configurable filtering and signal routing, thereby simplifying the frequency synthesizer implementation
5Reliability
If low-IF architecture with complex baseband filter is used, then receiver selectivity is maximized and dynamic range requirements are relaxed, but the complex filter implementation becomes difficult at higher IF frequencies
Solution Approach 1:
The patent implements a dynamic filtering approach using a complex filter with variable center frequency that can be reconfigured based on the operating band and IF frequency. This allows the filter to adapt its characteristics to maintain optimal selectivity across different frequency ranges, making the implementation feasible at higher IF frequencies where fixed complex filters would be difficult to implement
Data Source
AI summary
A Radio Frequency (RF) receiver is provided. The RF receiver is configured to simultaneously receive at least two radio frequency bands with a single receiver path. The RF receiver comprises a single local oscillator (LO), and the RF receiver is configured to filter a received signal using a complex filter having a variable center frequency. In accordance with another aspect, many RF receivers are combined to form an aggregate carrier receiver.