Wireless Transceiver IIP2 Calibration Using Native RF Test Circuits
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Solution Overview
Problem
Current IIP2 calibration schemes for wireless transceivers are cumbersome and time-consuming, requiring extensive testing and expensive equipment, and there is no known built-in-self-test (BIST) scheme for self-testing and auto-calibration, which increases chip size and cost.
Innovation Solution
An integrated automatic IIP2 calibration system that generates a test RF signal using native transceiver circuits and additional test adaptor circuits, minimizing additional circuitry and allowing on-chip IIP2 testing and calibration, enabling calibration after device assembly and reducing testing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional IIP2 calibration schemes are used, then IIP2 calibration can be performed, but the process is cumbersome and time-consuming requiring extensive testing and expensive external equipment
Solution Approach 1:
The patent implements a built-in self-test (BIST) scheme where the transceiver automatically generates test signals and performs IIP2 calibration without external equipment. The test signal generator uses native circuits to create test tones, and the calibration circuit automatically measures and adjusts IIP2 parameters, enabling the system to calibrate itself independently.
Solution Approach 2:
The patent introduces a calibration circuit as an intermediary component that bridges the test signal generator and the receiver path. This calibration circuit processes test signals, measures IIP2 distortion products, and generates compensation signals to adjust the receiver path, thereby enabling automatic calibration without external testing equipment.
2Ease of manufacture
If built-in-self-test (BIST) scheme is implemented for IIP2 calibration, then testing can be performed without external equipment, but chip size increases
Solution Approach 1:
The patent designs the test signal generator to use existing native circuits within the transceiver for generating test signals, rather than adding completely separate dedicated test equipment. The same RF paths, mixers, and amplifiers used for normal operation are utilized for IIP2 calibration, making the native circuits serve dual purposes and minimizing additional chip area.
Solution Approach 2:
The calibration circuit is integrated with the existing receiver path circuits, sharing common components such as mixers, amplifiers, and signal paths. The compensation signals generated by the calibration circuit are injected into the existing receiver path, merging the calibration function with the operational circuits to minimize additional area overhead.
3Measurement precision
If extensive testing is performed for IIP2 calibration, then calibration accuracy can be achieved, but manufacturing costs increase
Solution Approach 1:
The automatic BIST scheme eliminates the need for expensive external testing equipment and manual calibration procedures. The transceiver automatically generates test signals, measures IIP2 distortion, and applies compensation during manufacturing or even in-field, significantly reducing testing costs while maintaining calibration accuracy through automated measurement and adjustment.
Solution Approach 2:
The calibration circuit implements a feedback mechanism where test signals are passed through the receiver path, the resulting IIP2 distortion products are measured, and compensation signals are generated based on the measured distortion level. This closed-loop feedback ensures accurate IIP2 calibration by continuously adjusting the receiver path to minimize distortion.
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 reduces circuit overhead, testing time, and costs by utilizing existing native circuits for generating RF test signals, allowing for efficient IIP2 calibration without the need for external equipment, thus minimizing chip area and manufacturing costs.
Implementation Method 1
down-converted to baseband frequency R_CLK by mixer 32
Implementation Method 2
An RF input signal RFin is amplified by low noise amplifier 30
Implementation Method 3
The resulting output signal is then converted to a digital signal D_SIGNAL by ADC 38
Data Source
AI summary
An integrated automatic IIP2 calibration architecture for wireless transceivers is disclosed. The architecture enables a wireless transceiver to generate a test radio frequency (RF) signal having a second order tone with minimal additional circuitry. In particular, the test RF signal is generated using a combination of native transceiver circuits and test adaptor circuits. Native transceiver circuits are those circuits implemented on the transceiver chip for executing native transceiver functions during normal operation, which can be used for generating the test (RF) signal. Test adaptor circuits are added to the transceiver chip, more specifically to the native circuits, for enabling the native circuits to generate the test RF signal in a self-test mode of operation. Circuits for implementing a particular IIP2 minimizing scheme can be included on the transceiver chip for automatic IIP2 calibration during the self-test mode of operation.