RF Transceiver PLL Switching to Cut VCO Interference and Power
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Solution Overview
Problem
In ultra-low power (ULP) systems, RF transceivers consume significant power due to the continuous operation of voltage-controlled oscillators (VCOs) and phase-locked loops (PLLs), leading to high power consumption and interference between multiple VCOs when not adequately isolated.
Innovation Solution
A transceiver design that includes a phase-locked loop (PLL) with a common control circuit and switches for VCOs, a mismatch compensation device, and a leakage compensation device to optimize power usage and reduce interference by controlling the VCOs' operation based on transmission and reception modes, and using quenching waveform generators to prevent overlapping oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the PLL and VCO operate continuously to maintain frequency stability, then phase noise characteristics are improved, but power consumption increases
Solution Approach 1:
The patent implements periodic action by controlling the PLL and VCO to operate only during required time periods (transmission or reception modes) rather than continuously. The controller activates the PLL and VCO when needed and deactivates them when not needed, achieving periodic operation that reduces power consumption while maintaining frequency stability during active periods
Solution Approach 2:
The patent applies dynamics by making the PLL and VCO operational state variable rather than fixed. The controller dynamically adjusts the operational state of the PLL and VCO based on transmission/reception mode requirements, enabling the system to adapt between active and inactive states to optimize the trade-off between phase noise performance and power consumption
2Adaptability or versatility
If multiple VCOs operate simultaneously to support both transmission and reception, then communication functionality is improved, but interference between VCOs increases
Solution Approach 1:
The patent uses periodic action by implementing time-division multiplexing where the single VCO operates periodically in transmission mode and reception mode rather than continuously in both modes simultaneously. This temporal separation eliminates interference between transmission and reception VCOs while maintaining full communication functionality through sequential operation
Solution Approach 2:
The patent applies merging by combining multiple VCO functions into a single VCO that serves both transmission and reception purposes. Instead of using separate VCOs for Tx and Rx that would interfere with each other, the system merges the functions and uses a single VCO controlled by the controller to activate only when needed for the current operation mode
Data Source
AI summary
A transceiver may include a reception (Rx) radio frequency (RF) part configured to process a received signal, a transmission (Tx) RF part configured to process a transmitted signal, and a phase lock loop (PLL) configured to provide a reception frequency to the reception RF part and provide a transmission frequency to the transmission RF part. The PLL may be controlled according to whether the reception RF part or the transmission RF part is on. In addition, a transceiver may include quenching waveform generator (QWGs) to control quenching waveforms of the RF parts corresponding to a plurality of antennas. The quenching waveforms may be generated respectively by VCOs operating at a same frequency. The QWGs may control the VCOs such that the quenching waveforms do not overlap.