Multi-Band RF Receiver With Shared Down-Conversion and AGC
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Solution Overview
Problem
Current radio frequency receivers consuming significant area and power to support multiple bands, with I/Q imbalance and calibration challenges, and varying signal strengths across bands complicating simultaneous multiple band reception.
Innovation Solution
A radio frequency receiver with parallel receiving paths, each equipped with low noise amplifiers and automatic gain control, combining signals at a common summation node and down-converting using a mixer circuit, with a current driver maintaining low impedance and dynamic impedance adjustment to ensure constant frequency and linearity performance, and separate I/Q imbalance correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple parallel receiving paths are used to support multiple frequency bands, then the receiver can simultaneously receive multiple bands, but the area consumption and power consumption increase due to replication of baseband blocks
Solution Approach 1:
The patent merges multiple receiving paths by combining their RF outputs at a common summation node before down-conversion, rather than processing each band separately through independent baseband blocks. This sharing of common components (mixer, baseband processing) significantly reduces the total circuit area while maintaining multi-band reception capability.
Solution Approach 2:
The common mixer and baseband processing blocks are designed to handle multiple frequency bands universally. The system uses a single set of down-conversion and baseband processing resources that can process signals from any of the multiple RF bands, eliminating the need for dedicated baseband blocks for each band.
2Adaptability or versatility
If multiple parallel receiving paths with separate local oscillators are used, then each band can be processed independently, but power consumption increases and interaction between local oscillator frequencies degrades system performance
Solution Approach 1:
The patent merges the local oscillator resources by using a single common local oscillator for down-converting all multiple RF bands, rather than employing separate local oscillators for each band. This eliminates the power consumption of multiple local oscillators and prevents harmful interactions between them, while still enabling independent processing of each band through the shared oscillator.
3Adaptability or versatility
If signals are combined at radio frequency in power using power combiners, then multiple bands can be summed, but loss is introduced in the combiner and driving impedance becomes too low degrading mixer performance
Solution Approach 1:
The patent introduces a current driver circuit as an intermediary between the parallel RF receiving paths and the common mixer. This current driver serves as a mediator that properly buffers and drives the common summation node, maintaining appropriate impedance levels and preventing the impedance mismatch and signal loss that would occur with direct power combining.
4Measurement precision
If I/Q imbalance calibration is performed for each receiver branch, then detection accuracy is maintained, but implementation becomes very hard especially when frequency dependent and number of parallel branches increases
Solution Approach 1:
The patent merges the I/Q calibration process by performing a single unified calibration for the entire multi-band receiver system rather than separate calibrations for each band. Since all bands share a common mixer and baseband processing, a single I/Q calibration procedure suffices to correct imbalances across all frequency bands, dramatically reducing calibration complexity while maintaining detection accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient, simultaneous multiple band reception with reduced power consumption and area usage, maintaining linearity and frequency response across varying signal strengths without I/Q imbalance issues.
Implementation Method 1
amplify the received radio frequency signal in a low noise amplifier
Implementation Method 2
down-convert said combined radio frequency signal to a lower frequency signal in a mixer circuit
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
A radio frequency receiver (40) comprises a plurality of parallel receiving paths (31.1, 31.2, 31.n), wherein each path (31.1; 31.2; 31.n) can receive a radio frequency signal in one of a plurality of radio frequency bands and amplify the received signal in a low noise amplifier. The amplified signals from the plurality of parallel paths (31.1, 31.2, 31.n) are combined to one combined radio frequency signal in a common summation node and down- converted to a lower frequency signal in a mixer circuit (5). Each low noise amplifier comprises a low noise transconductance circuit (14) providing a current signal to drive the common summation node, and an automatic gain control circuit in each path compensates for variations in signal strength independently of signal strengths of signals received by the other receiving paths. The receiver is suitable for simultaneous multiple band reception, where received signal strength can vary between the frequency bands.