Current-Domain Loopback Calibration for Long-Path Transceivers
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Solution Overview
Problem
Existing wireless communication devices face challenges in accurately calibrating transceiver paths due to interference and voltage drop issues, particularly when the transmitter and receiver are separated by long distances, leading to inaccuracies in gain and phase settings.
Innovation Solution
Implementing a loopback calibration path with a voltage-to-current converter to convert amplified voltage to current, which is then provided to the receiver path, avoiding voltage domain issues and reducing interference, and omitting current-to-voltage converters to minimize process-voltage-temperature-dependent variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage domain calibration is used in long-distance transceiver paths, then calibration can be performed, but voltage drop and interference occur leading to inaccuracies
Solution Approach 1:
The patent introduces a current domain as an intermediary for signal transmission during calibration. Instead of directly transmitting voltage signals over long distances (which causes voltage drop), the system converts voltage to current, transmits the current signal through the long-distance path, and then converts it back to voltage. This intermediary current domain transmission avoids the voltage drop problem while maintaining calibration accuracy.
Solution Approach 2:
The patent changes the fundamental parameter domain from voltage to current for the calibration signal transmission. By operating in the current domain instead of voltage domain during long-distance transmission, the system exploits the property that current signals are less susceptible to voltage drop effects over long traces, thereby maintaining signal integrity and calibration accuracy.
2Ease of operation
If current-to-voltage converters are included in the calibration path, then signal conversion is complete, but process-voltage-temperature-dependent variations increase
Solution Approach 1:
The patent extracts and removes the current-to-voltage converter from the calibration path. By eliminating this component, the system avoids the process-voltage-temperature-dependent variations that such converters introduce. The calibration is performed by comparing current signals directly, without requiring conversion back to voltage domain, thereby improving signal stability and reducing variability.
3Measurement precision
If traditional voltage domain calibration is used, then calibration can be performed, but interference between transmitter and receiver increases
Solution Approach 1:
The patent substitutes the voltage domain system with a current domain system for calibration signal transmission. This substitution changes the fundamental nature of the signal being transmitted, allowing the calibration to proceed without the interference problems that plague traditional voltage domain approaches in long-distance transceiver paths.
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 approach enhances calibration accuracy by reducing voltage drop and current consumption, thereby improving the gain and phase alignment between in-phase and quadrature paths, thus enhancing the overall performance of the transceiver.
Implementation Method 1
converting the amplified voltage to a current via a voltage-to-current converter of a loopback calibration path
Data Source
AI summary
Certain aspects of the present disclosure generally relate to electronic devices and, more particularly, to techniques and apparatus for calibrating a transceiver. One example apparatus generally includes: a transmitter path including a first transmit amplifier; a receiver path including a transconductance amplifier; and a loopback calibration path coupled between an output of the first transmit amplifier and an output of the transconductance amplifier, wherein the loopback calibration path comprises a voltage-to-current converter.