ILFD Calibration in Millimeter-Wave PLLs for Wider Locking Range
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Solution Overview
Problem
Conventional millimeter-wave phase-locked loops (PLLs) face challenges due to limited locking range and high power consumption of injection-locked frequency dividers (ILFDs), making them difficult to implement in millimeter-wave communication devices, especially in mobile applications.
Innovation Solution
A millimeter-wave PLL design that incorporates an ILFD with calibration circuitry to determine optimal control signals for ILFD operation near the center of its locking range, using a look-up table to store values for various VCO frequency bands and a digital-to-analog converter to generate divider control voltages, along with a programmable second divider stage to adjust output frequencies, thereby extending the locking range while reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional ILFDs are used in millimeter-wave PLLs, then the PLL can operate at millimeter-wave frequencies, but the locking range is limited and power consumption is high
Solution Approach 1:
The patent implements dynamic adjustment of the ILFD control signal through calibration circuitry that automatically tunes the control voltage to optimize locking range. The system transitions from static conventional ILFD operation to dynamic adaptation by measuring locking range boundaries and adjusting control signals in real-time, allowing the ILFD to maintain optimal performance across varying operating conditions while minimizing power consumption.
Solution Approach 2:
The patent changes the control signal parameters (voltage level and timing) of the ILFD to extend locking range. By adjusting the control signal to operate near the center of the locking range rather than at extreme values, the system achieves broader frequency coverage and improved stability without proportionally increasing power consumption, resolving the contradiction between adaptability and energy use.
2Adaptability or versatility
If ILFD control signals are adjusted to extend locking range, then adaptability improves, but power consumption increases
Solution Approach 1:
The patent performs preliminary calibration to determine the optimal ILFD control signal settings before normal operation. The calibration circuitry pre-measures the locking range boundaries and stores the optimal control signal values in a lookup table. During actual PLL operation, these pre-determined settings are used directly without requiring continuous adjustment, achieving extended locking range while avoiding the continuous power consumption that would result from active tuning mechanisms.
Solution Approach 2:
The system uses self-calibration where the ILFD and calibration circuitry automatically determine their own optimal operating parameters without external intervention. The calibration process measures the actual locking range of the specific hardware instance and configures the control signals accordingly, enabling the system to adapt to its own characteristics and achieve optimal performance with minimal power consumption.
3Adaptability or versatility
If calibration circuitry is added to determine optimal control signals, then device complexity increases, but locking range and power efficiency improve
Solution Approach 1:
The patent merges the calibration circuitry with the existing PLL structure, integrating the locking range measurement and control signal determination functions into the available hardware resources. The calibration circuitry shares components with the PLL's frequency synthesis path, and the control signal generation is combined with the existing voltage-controlled oscillator control logic, reducing the net increase in device complexity while achieving extended locking range and improved power efficiency.
4Adaptability or versatility
If ILFD operates at edges of locking range to maximize frequency coverage, then adaptability improves, but stability and reliability deteriorate
Solution Approach 1:
The patent implements feedback through calibration circuitry that measures the actual locking range boundaries and uses this information to position the operating point near the center of the locking range. The system continuously monitors frequency acquisition and maintains optimal control signals based on measured performance, providing feedback that prevents operation at unstable edges while preserving broad frequency coverage through adaptive retuning when conditions change.
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
The solution enhances the locking range of ILFDs while minimizing power consumption, enabling more efficient and reliable millimeter-wave communication in mobile devices by ensuring stable operation across different frequency bands and compensating for component variations.
Implementation Method 1
a first stage and a second stage arranged in a ring-oscillator configuration, each stage including a pseudo-differential pair of transistors and a quarter-wavelength transmission line coupled between sources of the pseudo-differential pair and ground
Data Source
AI summary
Embodiments of a millimeter-wave phase-locked loop with an injection-locked frequency divider (ILFD) are generally described herein. Other embodiments may be described and claimed. In some embodiments, the ILFD uses a quarter-wavelength transmission line. A method of calibrating an ILFD is also provided to allow the ILFD to operate at or near the center of its locking range for each of a plurality of VCO oscillating frequency bands.