Resistive Combiner Signal Routing Reduces Jitter
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Solution Overview
Problem
Active multiplexers used in signal routing circuits contribute significant noise, limiting the phase noise floor and jitter of clock signals, which is a concern for applications requiring low jitter such as high-performance data converters and microwave backhaul systems.
Innovation Solution
Employing passive resistive signal combiners to reduce phase noise and jitter, with resistor networks configured to minimize thermal noise, allowing for improved signal routing by selecting between different clock sources or digital signals without the noise introduced by active multiplexers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If active multiplexers are used for signal routing, then signal selection capability is improved, but phase noise and jitter increase
Solution Approach 1:
The patent extracts and removes the active multiplexer component from the signal routing path. Instead of using an active multiplexer to select between clock sources, the invention routes signals through passive resistive combiners only, eliminating the active switching element that generates phase noise and jitter. This extraction of the problematic active component resolves the contradiction by maintaining signal selection capability through passive means while removing the source of harmful noise.
Solution Approach 2:
The patent introduces passive resistive combiners as intermediary elements between clock sources and the output. These resistive combiners serve as mediators that allow multiple clock signals to be combined and routed without requiring active switching. The resistive combiners provide the necessary signal routing functionality while maintaining a low noise floor, thus resolving the contradiction between signal selection capability and noise generation.
2Object-affected harmful factors
If passive resistive combiners are used instead of active multiplexers, then phase noise and jitter are reduced, but signal routing control capability is diminished
Solution Approach 1:
The patent implements dynamic control of passive resistive combiners through buffered switch elements. The buffers are controlled by selection signals that dynamically enable or disable specific input paths. This dynamic control mechanism allows the passive resistive combiner structure to adapt its routing behavior in real-time, maintaining ease of operation despite using passive components. The dynamic switching capability resolves the contradiction by providing operational flexibility without requiring active multiplexing in the traditional sense.
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
The use of passive resistive combiners reduces phase noise and jitter, enhancing the performance of signal routing circuits, making them suitable for applications that require low noise levels, such as high-performance data converters and frequency synthesizers for electronic warfare systems.
Implementation Method 1
the thermal noise generated by the combiners, if any, is substantially lower (e.g., by 10 dB or more) than the power level of the signals to be routed
Data Source
AI summary
A signal routing circuit is disclosed which employs resistive combiners to reduce signal jitter. A signal routing circuit configured according to an embodiment comprises an input stage including a plurality of buffer circuits. Each of the buffer circuits is controlled by a selection signal to enable an input signal at an input port of the buffer circuit to generate an output signal at an output port of the buffer circuit. The signal routing circuit also includes a plurality of resistors to couple the output port of each of the buffer circuits of the input stage to a summing junction. The signal routing circuit further includes an output stage including an additional buffer circuit. The input port of the additional buffer circuit is coupled to the summing junction, and the output port of the additional buffer circuit is configured to provide the routed output signal based on the selection signals.