Multi-band RF Transmitter Delay Correction for Signal Distortion
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Solution Overview
Problem
Radio transmitting devices face increased distortion due to synchronous deviations in delay times between input signals in multiple bands, leading to inefficiencies in power amplifier performance.
Innovation Solution
A radio transmitting device and method that include a multi-band RF signal generator, a power amplifier, a distortion compensation control signal generating unit, and a transmitter delay correction unit to synchronize and correct delays in baseband signals, thereby compensating for distortion characteristics in the power amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single power amplifier is used to amplify RF signals in multiple bands simultaneously, then device size and cost are reduced, but synchronous deviation in delay times between input signals causes increased distortion
Solution Approach 1:
The patent applies preliminary action by introducing delay correction units that pre-adjust the delay times of baseband signals before they reach the power amplifier. This preliminary synchronization prevents synchronous deviation from occurring in the first place, allowing multiple frequency bands to be properly aligned when amplified by the single power amplifier, thus resolving the contradiction between device simplicity and signal precision
2Device complexity
If a single power amplifier is used to amplify RF signals in multiple bands simultaneously, then device cost is reduced, but distortion characteristics of the power amplifier are not compensated
Solution Approach 1:
The patent introduces predistortion units that apply preliminary compensation for the power amplifier's distortion characteristics to the baseband signals before amplification. By pre-distorting the input signals in the opposite direction of the expected distortion, the system counteracts the non-linear effects of the power amplifier, maintaining signal fidelity while using a single, cost-effective amplifier for multiple bands
Solution Approach 2:
The patent implements feedback mechanisms where the output signal from the power amplifier is monitored and used to adjust the predistortion and delay correction parameters. This closed-loop feedback ensures that distortion compensation remains accurate even as operating conditions change, resolving the contradiction between using a simple single amplifier and maintaining high signal precision
3Device complexity
If delay correction is not applied to baseband signals, then device complexity is reduced, but synchronous deviation increases causing output signal distortion
Solution Approach 1:
The patent applies preliminary delay correction to baseband signals before they enter the power amplifier stage. By pre-synchronizing the delay times of signals from different frequency bands, the system prevents synchronous deviation from developing, ensuring that the power amplifier receives properly aligned inputs and produces high-quality output signals without requiring complex post-processing
Data Source
AI summary
The amount of distortion of the output signal increases due to a difference in delay times in a plurality of paths in a radio transmitting device transmitting RF signals in a plurality of bands, therefore, a radio transmitting device according to an exemplary aspect of the present invention includes: a multi-band RF signal generator making each of a plurality of input baseband signals carried by a carrier wave with each of different frequencies, and outputting the carrier wave as a radio frequency signal; a power amplifier amplifying and outputting the radio frequency signal; a distortion compensation control signal generating unit applying a distortion compensating function, which compensates a distortion characteristic of the power amplifier, to the each of the plurality of input baseband signals; and a transmitter delay correction unit correcting a difference in delays which the plurality of input baseband signals receive respectively in the multi-band RF signal generator.