RF Band Filter Switching Timing to Reduce Receive Signal Leakage
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Solution Overview
Problem
Switching RF signals between different communication bands and technologies in wireless communication devices causes disturbances and unwanted signal leakage due to differences in transition times of switching elements, leading to glitches in receive path gain and phase.
Innovation Solution
Implement a radio frequency switching system with complementary control signals and delayed switching of band filters to minimize signal leakage by synchronizing the ON and OFF times of switch elements, ensuring at least one filter remains coupled to the antenna during transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If RF signals are switched between different communication bands using multiple band filters and switches, then the system supports multiple communication technologies and bands, but signal leakage and disturbances occur during switching due to differences in transition times
Solution Approach 1:
The patent applies preliminary action by calculating the transition time difference (delta) between complementary switch elements in advance and using this pre-determined value to delay the control signal. This allows the switching sequence to be optimized beforehand, ensuring that the second switch element turns off before the first switch element turns on, thereby preventing signal leakage during the transition between communication bands.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the timing parameter of the control signal based on the measured or calculated transition time difference (delta) between switch elements. By changing the delay parameter of the control signal, the system optimizes the switching sequence to eliminate simultaneous conduction of complementary switches, thus resolving the signal leakage issue while maintaining support for multiple communication bands.
2Speed
If complementary control signals are used to switch between band filters, then switching speed is improved, but signal leakage occurs due to simultaneous conduction of switch elements
Solution Approach 1:
The patent applies preliminary action by pre-calculating the transition time difference (delta) between the ON to OFF time (Toff) and OFF to ON time (Ton) of complementary switch elements. This pre-determined delta value is then used to delay the control signal, ensuring that the switching sequence is optimized in advance to prevent simultaneous conduction, thereby maintaining fast switching speed while eliminating signal leakage.
Solution Approach 2:
The patent applies the skipping principle by rushing through the transition period with a carefully timed delay. The control signal is delayed by exactly the delta time, which allows the second switch element to turn off completely before the first switch element turns on. This rushed, precisely-timed transition skips the harmful simultaneous conduction state, achieving both fast switching and signal leakage prevention.
3Device complexity
If switch elements are switched simultaneously, then switching is simplified, but gain and phase anomalies occur in the receive path
Solution Approach 1:
The patent applies preliminary action by pre-determining the transition time difference (delta) between complementary switch elements and incorporating this knowledge into the control signal timing. This preliminary calculation allows the system to use a simple delayed control signal approach rather than complex real-time control, thereby maintaining low device complexity while ensuring signal integrity by preventing simultaneous switch conduction that would cause gain and phase anomalies.
Data Source
AI summary
A (RF) switching system for minimizing received signal leakage during switching including a plurality of band filters comprising a first band filter, a second band filter, and a third band filter, first and a second antenna, and a switch configured to selectively couple the first, second and third filters to the first and second antennas and configured to receive complementary control signals, wherein at least the first and the second filter are configured to be simultaneously coupled to the first antenna and the switch is further configured to delay at least one of the complementary control signals when the switch, in response to the complementary control signals, is configured to selectively connect the first antenna to the third filter instead of the second filter while the first filter is coupled to the first antenna and a first communication path through the first filter to the first antenna is active.