RF Carrier Phase Continuity During Duty Cycling
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Solution Overview
Problem
In cellular radios, RF carrier generation modules consume a significant portion of the power budget due to the need to maintain phase continuity between duty cycles, leading to increased power consumption and incompatibility with standard packet formats when duty-cycled.
Innovation Solution
A method for compensating carrier tone generation by determining phase differences between duty cycles using a time-to-digital converter module, allowing RF carrier generation modules to be switched off during OFF cycles while maintaining phase continuity, eliminating the need for reacquiring the carrier phase and sampling offset.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If RF carrier generation modules are duty-cycled (switched off during OFF cycles), then power consumption is reduced, but phase continuity between duty cycles cannot be maintained
Solution Approach 1:
The system separates the RF carrier generation function into two independent parts: a reference frequency source that remains continuously active to maintain phase continuity, and a PLL that can be duty-cycled for power savings. This segmentation allows each component to fulfill its specific role without compromising the other.
Solution Approach 2:
A time-to-digital converter (TDC) is introduced as an intermediary component that measures the time difference between the continuous reference frequency and the duty-cycled PLL output. This TDC enables phase continuity to be tracked and compensated even when the PLL is switched off, bridging the gap between power-saving duty-cycling and phase continuity requirements.
2Stability of the object's composition
If phase continuity is maintained by keeping PLL powered on, then phase continuity is preserved, but power consumption increases
Solution Approach 1:
The reference frequency source performs preliminary action by continuously generating phase reference information even when the PLL is off. This advance preparation of phase reference data enables the PLL to quickly reacquire phase continuity when turned back on, eliminating the need to maintain full PLL power consumption continuously.
Solution Approach 2:
The system implements feedback through the TDC that continuously monitors the phase relationship between the reference frequency and PLL output. This feedback mechanism provides phase error information that guides the PLL's phase acquisition process, enabling efficient duty-cycled operation while maintaining phase continuity through controlled feedback during ON cycles.
3Use of energy by moving object
If PLL is switched off during OFF cycles, then power consumption decreases, but time is required to reacquire carrier phase and sampling offset
Solution Approach 1:
The reference frequency source continuously maintains phase information during OFF cycles, performing preliminary preparation so that when the PLL restarts, it can immediately use this pre-maintained phase reference to minimize reacquisition time, rather than starting from scratch.
Solution Approach 2:
The system replaces the traditional mechanical/sequential phase acquisition process with a time-digital conversion approach. The TDC converts time differences into digital values that can be processed and used for phase compensation, enabling faster and more efficient phase reacquisition compared to conventional methods.
4Use of energy by moving object
If conventional duty-cycling is implemented without phase continuity, then power consumption is reduced, but packet format compatibility is compromised
Solution Approach 1:
Instead of trying to maintain phase continuity through traditional means that would prevent duty-cycling, the system inverts the approach by allowing the PLL to be duty-cycled and using the continuous reference frequency with TDC measurement to achieve phase continuity. This inverted methodology enables both power savings and standard packet format compatibility.
Solution Approach 2:
The TDC acts as an intermediary that enables the system to bridge the gap between duty-cycled operation and phase continuity requirements. By measuring time differences and providing this information for phase compensation, the TDC allows the system to maintain compatibility with standard packet formats while implementing aggressive duty-cycling for power savings.
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 efficient duty-cycling, reducing power consumption and maintaining phase continuity between ON cycles, thereby optimizing power usage in low-power wireless communication technologies like LTE and WLAN.
Implementation Method 1
determining a first time difference between the carrier frequency signal and the reference frequency signal during a first ON cycle of a duty-cycle sequence, and a second time difference between the carrier frequency signal and the reference frequency signal during a second ON cycle
Data Source
AI summary
A method of compensating carrier tone generation between duty cycles includes receiving a carrier frequency signal and a reference frequency signal, where the carrier frequency signal is mixed with a communication signal in a signal path. The method includes determining a first and second time differences between the carrier frequency signal and the reference frequency signal at respective clock edges of the reference frequency signal. The method includes converting the first time difference to a first corresponding phase value and the second time difference to a second corresponding phase value based on an operating frequency, and determining a phase difference between the first corresponding phase value and the second corresponding phase value. In turn, the method includes adjusting the communication signal with the phase difference independent of the signal path to maintain phase continuity in the signal path between the duty cycles.