Power Amplifier Interstage Filtering for Multiradio Transmitters
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Solution Overview
Problem
In multiradio transceivers, the broad bandwidth of power amplifiers amplifies unwanted signals and noise across frequency bands, leading to inefficiencies and increased power consumption due to strict filtering requirements, which are typically addressed after the power amplifier, resulting in decreased transmitter efficiency and increased heat.
Innovation Solution
Incorporating impedance circuitry with switching mechanisms between power amplifier stages to form and switch impedance at frequencies related to the local oscillator frequency, allowing for filtering within the power amplifier stages, thereby relaxing filtering requirements after the amplifier and reducing signal and noise amplification across unwanted bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If filtering is performed after the power amplifier, then unwanted receiver band signals are filtered away, but transmitter efficiency decreases and power consumption increases
Solution Approach 1:
The patent applies preliminary action by inserting filtering stages between power amplifier stages rather than after the final amplification stage. This allows unwanted frequency components to be removed before they are further amplified, reducing the filtering burden on subsequent stages and improving overall transmitter efficiency while maintaining signal quality.
Solution Approach 2:
The patent segments the filtering function across multiple stages within the power amplifier chain. Instead of relying on a single filtering stage after complete amplification, the filtering is distributed across intermediate stages, allowing each stage to handle less severe filtering requirements and improving overall system efficiency.
2Device complexity
If the power amplifier operates with constant gain in both transmitter and receiver bands, then amplification is simplified, but strict filtering requirements are imposed on the output filter
Solution Approach 1:
The patent applies preliminary action by performing frequency-selective filtering at intermediate stages before the signal reaches the final amplification and output filtering stages. This preliminary frequency selection reduces the burden on the output filter, allowing it to operate with more relaxed specifications while maintaining the required filtering performance.
3Productivity
If no filtering is performed before the power amplifier, then the filter capability after the amplifier limits the maximum gain, but adding filtering before the amplifier increases device complexity
Solution Approach 1:
The patent segments the filtering function across multiple stages within the power amplifier chain. Instead of relying on a single filtering stage after complete amplification, the filtering is distributed across intermediate stages, allowing each stage to handle less severe filtering requirements and improving overall system efficiency.
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
This approach increases the power amplifier efficiency by reducing losses and heat, allowing for higher gain without additional filters, and enables efficient operation across different frequency bands with minimal configuration changes.
Implementation Method 1
an impedance circuitry for forming an impedance at a frequency related to the frequency of the local oscillator
Implementation Method 2
a switch for switching the impedance of the impedance circuitry means to RF frequency
Implementation Method 3
a power amplifier amplifying an RF signal and having multiple stages
Data Source
AI summary
A filtering method, a transceiver and a transmitter are provided. The transmitter comprises a power amplifier amplifying an RF signal and having multiple stages, and a local oscillator, the power amplifier comprising between at least two stages of the power amplifier an impedance circuitry for forming an impedance at a frequency related to the frequency of the local oscillator, and a switch for switching the impedance of the impedance circuitry means to RF frequency.