RF Circuit Testing with Half-Wavelength Line
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Solution Overview
Problem
Testing high-frequency radio-frequency circuits above 20 GHz is challenging due to difficulties in generating differential test signals with a 180-degree phase difference, which is exacerbated by mechanical and production tolerances, and the high cost of specialized equipment, leading to higher error rates in functional testing.
Innovation Solution
A radio-frequency circuit design that includes a signal processing unit with two signal inputs connected by a line of length corresponding to an odd multiple of half the wavelength, allowing for the generation of a quasi-symmetrical input signal using an asymmetrical signal generator and conventional measuring tips, enabling cost-effective testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If differential test signals are generated using conventional equipment, then the testing can be performed with standard devices, but the phase difference of 180 degrees cannot be ensured due to mechanical tolerances and production tolerances
Solution Approach 1:
The patent uses an asymmetrical signal generator to generate test signals, combined with a line of specific length (odd multiple of half-wavelength) to create the required symmetrical differential signal at the circuit inputs. This approach accepts asymmetry in the generation equipment while achieving symmetry in the actual test signal applied to the device under test.
Solution Approach 2:
The patent changes the physical parameter of the connecting line (its length) to be an odd multiple of half the wavelength of the test signal. This parameter change transforms the asymmetrical input signal into a symmetrical differential signal at the circuit inputs, resolving the phase difference issue without requiring precision differential equipment.
2Manufacturing precision
If specialized frequency generators with symmetrical output are used, then accurate differential test signals can be generated, but the cost becomes very high
Solution Approach 1:
Instead of using expensive specialized differential signal generators, the patent creates a functional copy of the differential signal using standard equipment combined with a transmission line. The line acts as a signal transformer that replicates the effect of a differential generator without requiring the expensive specialized device.
Solution Approach 2:
The patent introduces a transmission line as an intermediary element between the asymmetrical signal generator and the differential circuit under test. This intermediary transforms the asymmetrical signal into a symmetrical differential signal, enabling accurate testing without expensive specialized equipment.
3Ease of manufacture
If DC and low-frequency properties are measured instead of high-frequency functional testing, then the testing can be performed with available equipment, but the actual function of the components is not measured resulting in higher error detection rates
Solution Approach 1:
The patent uses periodic high-frequency test signals (radio frequency signals) to test the actual functional performance of the circuit. This periodic high-frequency action reveals functional defects that DC and low-frequency measurements cannot detect, while still using available measurement equipment through the signal transformation approach.
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 allows for effective functional testing of high-frequency circuits with reduced error rates and lower costs by generating a quasi-symmetrical input signal from an asymmetrical input, using standard equipment and measurement tools.
Implementation Method 1
a line which connects the signal inputs and has a length which essentially corresponds to an odd-numbered multiple of half the wavelength of the input signal
Data Source
AI summary
A radio-frequency circuit has a signal processing unit for processing a symmetrical input signal, two signal inputs for receiving the symmetrical input signal, a connection which is used as a ground point for the symmetrical signal, and a line which connects the signal inputs and has a length which essentially corresponds to an odd-numbered multiple of half the wavelength of the input signal. A method for testing a radio-frequency circuit having a signal processing unit for processing a symmetrical input signal is additionally provided.