RF Test Signal Generator Circuit for Receiver Linearity
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Solution Overview
Problem
Existing RF test signal generators in MMICs are not suitable for quantitative characterization of the linearity of RF receiver circuits due to intermodulation products (IMPs) caused by the modulator, making it difficult to distinguish between distortions from the modulator and the receiver circuit, which affects the accuracy of radar measurements.
Innovation Solution
A test signal generator circuit using two separate modulators to generate RF test signals by modulating an RF oscillator signal with distinct single-tone signals, which are then combined linearly to prevent intermodulation distortions, allowing for the unique attribution of IMPs to the receiver circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single modulator is used to generate RF test signals, then device complexity is reduced, but intermodulation products are generated that prevent accurate characterization of receiver circuit linearity
Solution Approach 1:
The patent divides the modulation function into two separate modulators (first modulator and second modulator) instead of using a single modulator. Each modulator processes a different single-tone signal independently, which prevents intermodulation products from being generated within the modulation stage. This segmentation allows for accurate linearity characterization of the receiver circuit while maintaining manageable device complexity through modular architecture.
Solution Approach 2:
The patent introduces an RF combiner circuit as an intermediary component that combines the outputs of the two modulators. This combiner acts as a mediator that linearly merges the two modulated signals without generating additional intermodulation products, thereby preserving measurement accuracy while enabling the use of multiple modulators in the test signal generation process.
2Measurement precision
If multiple modulators are used to generate RF test signals, then intermodulation distortions are prevented, but device complexity increases
Solution Approach 1:
The patent divides the modulation function into two separate modulators (first modulator and second modulator) instead of using a single modulator. Each modulator processes a different single-tone signal independently, which prevents intermodulation products from being generated within the modulation stage. This segmentation allows for accurate linearity characterization of the receiver circuit while maintaining manageable device complexity through modular architecture.
Solution Approach 2:
The patent changes the operational parameters of the test signal generation by using two modulators with different single-tone signal frequencies. This parameter differentiation ensures that the modulators operate in distinct frequency domains, preventing intermodulation distortions while allowing the system to maintain a controlled and predictable complexity level through standardized modulator designs.
3Measurement precision
If intermodulation products are present in the test signal, then device complexity is reduced, but the ability to uniquely attribute IMPs to the receiver circuit is lost
Solution Approach 1:
The patent segments the test signal generation into two independent modulation paths, each handling a different single-tone signal. This segmentation ensures that intermodulation products can only originate from the receiver circuit under test and not from the signal generation process itself, enabling unique attribution of measured IMPs to the receiver circuit while maintaining a relatively simple overall circuit architecture.
Solution Approach 2:
The RF combiner circuit serves as an intermediary that linearly combines the outputs of the two modulators without introducing non-linearities. This intermediary component preserves the purity of the individual modulated signals and ensures that any intermodulation products detected during testing are solely attributable to the receiver circuit rather than the test signal generation process.
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 enables the generation of high-quality RF test signals without intermodulation products, allowing for accurate quantitative characterization of the linearity of the receiver circuit, thereby improving the reliability and accuracy of radar measurements.
Implementation Method 1
a first modulator, which is embodied to generate a first RF signal by virtue of the RF oscillator signal being modulated with a first signal
Data Source
AI summary
The description is of a circuit which, according to one example embodiment, comprises the following: an input circuit node for receiving an RF oscillator signal; a test signal generator circuit, which comprises at least one modulator and which is embodied to generate an RF test signal by modulating the RF oscillator signal. Further, the circuit comprises at least one receive channel with a receiver circuit and a coupler, which is embodied to feed the RF test signal into the receiver circuit.