Phase Shifter Switching Sequence for Glitch-Free Transitions
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Solution Overview
Problem
Phase shifters implementing high isolation switches experience glitches when transitioning from one phase shift to another, resulting in undesired amplitude, frequency, and phase changes at the output, which hinder data transmission.
Innovation Solution
Implementing time delays in the transition process of phase shifters by controlling the state of series and shunt switches to decouple and couple phase shifting elements in a specific sequence, reducing the duration of signal cancelation and shorting issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high isolation switches are used in phase shifters, then isolation between paths is improved, but glitching occurs during phase transitions
Solution Approach 1:
The control circuit activates the shunt switch of the new path before deactivating the series switch of the current path. This preliminary action ensures that the new path is already isolated and ready to receive the signal, preventing glitching during the transition between phase shift paths.
2Reliability
If series switches are turned OFF before series switches in the other path are turned ON, then path isolation is achieved, but signal cancelation and glitches occur
Solution Approach 1:
The control circuit performs preliminary activation of the shunt switch in the new path before deactivating the series switch in the current path. This ensures that the new path is prepared and isolated beforehand, preventing signal cancelation and glitches during the transition.
Solution Approach 2:
The control circuit inverts the traditional switching sequence by activating the shunt switch before deactivating the series switch, rather than following the conventional approach of deactivating first. This reversed sequence prevents both signal cancelation and glitches while maintaining path isolation.
3Reliability
If shunt switches are turned ON quickly for isolation, then isolation performance is improved, but shorting to ground and glitches occur
Solution Approach 1:
The control circuit activates the shunt switch in the new path in advance, before the series switch in the current path is deactivated. This preliminary action ensures that the new path is already isolated and ready, preventing shorting to ground and glitches during the transition.
Solution Approach 2:
The control circuit inverts the switching sequence by turning ON the shunt switch before turning OFF the series switch, rather than following the conventional sequence. This reversed approach prevents shorting to ground while maintaining effective isolation performance.
Data Source
AI summary
Methods and devices to reduce glitches in phase shifters implementing high isolation switches are disclosed. Such glitches occur at the output of the phase shifters when transitioning from one phase shift to another. The disclosed method implements delays in various steps of the phase shifter transitions. Exemplary embodiments implementing single-pole multi-throw are provided and exemplary performance of the disclosed methods are also presented. The described methods are also applicable to multi-step attenuators.