PLL Switching and Quenching Control in ULP RF Transceivers
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Solution Overview
Problem
In ultra-low power (ULP) RF transceivers, the phase-locked loop (PLL) and voltage-controlled oscillator (VCO) consume significant power, leading to high overall system power consumption and interference issues due to insufficient isolation between VCOs, which can cause signal recognition failures when interference signal amplitudes exceed received signal amplitudes.
Innovation Solution
A transceiver design that includes a PLL with a common control circuit connected to VCOs via switches, allowing power management based on RF part on/off states, and employs mismatch compensation and leakage compensation devices to optimize current usage and reduce phase noise, along with quenching waveform generators to prevent VCO interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the PLL and VCO are kept on continuously to ensure frequency stability, then phase noise is reduced, but power consumption increases significantly
Solution Approach 1:
The patent implements periodic action by controlling the PLL and VCO to operate only during specific time intervals (transmission or reception periods) rather than continuously. The PLL is activated before the scheduled TDD operation and deactivated after, creating a periodic on-off pattern that reduces average power consumption while maintaining performance during active periods
Solution Approach 2:
The patent applies preliminary action by activating the PLL and VCO in advance before the actual transmission or reception operation begins. This pre-activation ensures that the oscillators are already stable and locked when needed, preventing phase noise issues while allowing the system to remain off during idle periods
2Adaptability or versatility
If multiple VCOs operate simultaneously to support both Tx and Rx functions, then system functionality is improved, but interference between VCOs increases
Solution Approach 1:
The patent uses periodic action by implementing time-division control where the VCOs are activated in separate time slots corresponding to transmission and reception periods. This temporal separation ensures that only one VCO operates at a time, eliminating mutual interference while maintaining full system functionality through proper timing coordination
Solution Approach 2:
The patent applies segmentation by dividing the operation into distinct transmission and reception time slots, with corresponding separate VCO activations. This temporal segmentation isolates the VCO operations, preventing interference between them while still supporting both Tx and Rx functions through structured time management
3Use of energy by moving object
If the PLL is turned off to reduce power consumption, then energy usage decreases, but phase noise performance deteriorates
Solution Approach 1:
The patent implements periodic action by cycling the PLL between on and off states according to the TDD schedule. The PLL is turned on only during transmission or reception periods and turned off during idle periods, creating a periodic pattern that reduces average power consumption while ensuring phase noise performance is maintained during active operation
Solution Approach 2:
The patent applies preliminary action by activating the PLL in advance before each transmission or reception period. This pre-activation allows the PLL to establish stable locking and minimal phase noise before the actual operation begins, ensuring performance requirements are met while minimizing the duration of high-power operation
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.