Crystal-Less BLE Transceiver Using Packet-Recovered Frequency Reference
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Solution Overview
Problem
Traditional wireless transceivers rely on bulky and expensive crystal oscillators for local oscillator calibration, which hinders the development of true single-chip radios and is not suitable for wireless standards due to high power consumption and PVT sensitivity.
Innovation Solution
A crystal-less transceiver system that uses a receive circuit to recover a reference signal from an incoming wireless packet, with a first oscillator and a first phase lock loop (PLL) to adjust the oscillator frequency, and a transmit circuit with a second PLL to generate a carrier signal at a predetermined frequency, excluding the need for a crystal oscillator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a crystal oscillator is used for local oscillator calibration, then frequency accuracy is maintained, but device size, weight, and cost increase significantly
Solution Approach 1:
The patent extracts and removes the crystal oscillator from the transceiver system, replacing it with a crystal-less architecture that uses on-chip oscillators and frequency calibration techniques to achieve the required frequency accuracy without the bulky external crystal component
Solution Approach 2:
The transceiver performs self-calibration by recovering a reference frequency from received signals and using phase-locked loops to automatically adjust its oscillator frequencies, eliminating the need for external crystal oscillators while maintaining frequency accuracy
2Weight of stationary object
If integrated references like on-chip LC or relaxation oscillators are used, then device size is reduced, but power consumption increases or PVT sensitivity becomes too high
Solution Approach 1:
The patent implements feedback mechanisms through phase-locked loops that continuously monitor and adjust the oscillator frequencies based on recovered reference signals, enabling the on-chip oscillators to maintain frequency accuracy despite power consumption and PVT variations
Solution Approach 2:
The system dynamically adjusts oscillator parameters and frequency calibration values based on operating conditions and recovered reference frequencies, allowing the transceiver to adapt to PVT variations while maintaining compliance with wireless standards
3Weight of stationary object
If reference clock is recovered from received signal, then crystal oscillator is removed, but locking time increases and susceptibility to interference increases
Solution Approach 1:
The patent performs preliminary frequency calibration and reference recovery during the initial signal acquisition phase, preparing the phase-locked loops in advance to reduce the overall locking time and enable faster operation
Solution Approach 2:
The system uses dynamic frequency tuning and adaptive locking mechanisms that adjust the calibration process based on signal conditions, optimizing the balance between locking time and interference rejection capability
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
Enables a fully-integrated, low-power, and frequency-accurate wireless transceiver that meets wireless standards, with fast locking times and improved interference rejection, allowing for efficient communication without the bulk and cost of crystal oscillators.
Implementation Method 1
a first phase lock loop (PLL) is interfaced with the first oscillator. The first PLL is configured to, in response to detecting the wireless packet, adjust a first oscillator frequency of the first oscillator based on an incoming frequency of the incoming signal using the reference frequency
Implementation Method 2
A first oscillator generates a signal at a set of predetermined frequencies
Data Source
AI summary
A transceiver includes a receive circuit configured to receive an incoming signal and recover a reference signal at a reference frequency from the incoming signal. The incoming signal is a wireless packet. A first oscillator generates a signal at a set of predetermined frequencies. A first phase lock loop (PLL) interfaced with the first oscillator. The first PLL is configured to adjust a first oscillator frequency of the first oscillator based on an incoming frequency of the incoming signal using the reference frequency. A transmit circuit includes a second oscillator configured to generate a carrier signal at a predetermined frequency and a modulator configured to modulate data over the carrier signal at the predetermined frequency. The transmit circuit includes a second PLL interfaced with the second oscillator that sets the second oscillator to generate the carrier signal at the predetermined frequency using the reference signal. The transmit circuit transmits the modulated carrier signal.