Synchronized Power Measurement in MMW Front End Module
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Solution Overview
Problem
Existing methods for accurately measuring and controlling transmission power levels in phased array antenna assemblies, particularly in 5G millimeter wave systems, face challenges due to variations in power amplifier performance over time and temperature, as well as the effects of Time Division Duplex operation and amplitude tapering.
Innovation Solution
A communications device with a phased array antenna assembly that includes front-end IC chips equipped with TX power amplifiers, power sensors, and analog-to-digital converters, which capture and process power measurements synchronized with specific symbols in the communication protocol, adjusting gain elements to maintain target power levels while accounting for temperature and amplitude taper effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If power measurements are taken continuously in a phased array antenna assembly, then transmission power levels can be monitored accurately, but system complexity and processing overhead increase significantly
Solution Approach 1:
The system pre-identifies symbols of interest (such as synchronization symbols or reference symbols) based on the communication protocol timing structure before actual transmission occurs. When these predetermined symbols are detected, trigger signals are immediately generated to initiate power measurements only at these specific moments, avoiding continuous measurement and reducing system complexity while maintaining measurement accuracy for critical transmission events.
2Measurement precision
If power measurements are synchronized with symbol boundaries in TDD operation, then accurate power control is achieved, but timing synchronization complexity increases
Solution Approach 1:
The system utilizes feedback from the communication protocol's inherent timing structure (such as synchronization signals or frame structure indicators) to automatically determine when symbols of interest occur. This feedback mechanism allows the measurement system to automatically align with symbol boundaries without requiring complex external timing synchronization circuits, as the protocol itself provides the timing reference needed for synchronized power measurements.
3Stability of the object's composition
If temperature compensation is implemented for power amplifier variations, then transmission power stability is improved, but measurement and control system complexity increases
Solution Approach 1:
The system incorporates temperature sensors directly integrated with the power amplifier modules, allowing each PA to self-monitor its own temperature conditions. The measured temperature data is then used by the control system to apply compensation factors to the power measurements, enabling the system to automatically adjust for temperature-induced power variations without requiring external temperature control equipment or complex thermal management infrastructure.
4Measurement precision
If amplitude tapering is accounted for in power measurements, then individual PA power levels are accurately determined, but processing complexity increases
Solution Approach 1:
The system pre-stores or pre-calculates the amplitude tapering factors for each power amplifier in the array based on the desired antenna radiation pattern. These tapering factors are determined in advance during system configuration or initialization. When power measurements are taken, the system simply applies these predetermined factors to the measured values through straightforward multiplication, avoiding the need for complex real-time calculations while achieving accurate individual PA power determination that accounts for amplitude tapering effects.
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 solution enables precise and adaptive control of transmission power levels, ensuring optimal performance and compliance with emission requirements by accurately measuring and adjusting power settings in response to temperature variations and amplitude tapering effects.
Implementation Method 1
power sensor, for measuring the transmit power of the TX PA
Implementation Method 2
analog to digital converter (ADC) for obtaining a digital representation of the average transmit power
Implementation Method 3
determines adjustments, e.g. increase or decrease amounts with respect to individual gain elements in individual TX chains
Data Source
AI summary
A communications device including an array antenna assembly including a plurality of transmit chains, each with a transmit power amplifier, synchronously captures transmit power measurements for each power amplifier. A baseband transmitter in the communications device determines when a predetermined symbol in a protocol, e.g. a PSS SSB symbol, is to be transmitted and sends, e.g. via a SPI, a capture command to command each of the ADCs corresponding to the power amplifiers to synchronously capture a power measurement. Power measurements are captured at the boundary of the predetermined symbol, and the power measurements represent average transmit power levels corresponding to the symbol. The power measurements are communicated to the baseband transmitter which processes the data using calibration tables and taper information. Processed power measurements are compared to desired transmitter target levels and errors are determined. Based on the errors the gains of one or more TX chains are adjusted.