OTA DPD Calibration in MIMO Transceivers Without Coupler Chains
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Solution Overview
Problem
Current digital pre-distortion calibration methods for MIMO transceivers require dedicated DPD calibration chains, leading to increased circuit footprint and cost due to the need for components like couplers, variable attenuators, and multiplexers, which also introduce insertion loss and limit simultaneous transmission and reception modes.
Innovation Solution
The implementation of over-the-air (OTA) coupling between communication chains allows for DPD calibration without dedicated calibration chains, using the communication chains themselves to observe PA amplification, reducing the need for additional circuitry and enabling simultaneous transmission and reception modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dedicated DPD calibration chains are used, then DPD calibration can be performed, but circuit footprint and cost increase
Solution Approach 1:
The patent merges the DPD calibration function with existing communication chains by using one communication chain to transmit calibration signals and another to receive and observe the amplified signals. This eliminates the need for separate dedicated calibration chains, thereby reducing circuit footprint while maintaining DPD calibration capability.
Solution Approach 2:
The communication chains are designed to serve multiple functions: they can perform both regular communication operations and DPD calibration operations. By making the communication chains universal, the patent eliminates the need for dedicated calibration chains, reducing both circuit footprint and production cost.
2Reliability
If dedicated DPD calibration chains are used, then DPD calibration can be performed, but production cost increases
Solution Approach 1:
The patent merges the DPD calibration function with existing communication chains, eliminating the need for additional dedicated calibration components. This reduction in component count directly lowers production costs while maintaining full DPD calibration capability.
Solution Approach 2:
By designing communication chains to perform both regular communication and DPD calibration functions, the patent eliminates the need for separate calibration components, thereby reducing bill of materials cost and simplifying the manufacturing process.
3Reliability
If couplers and variable attenuators are used in DPD calibration, then calibration can be performed, but insertion loss increases
Solution Approach 1:
The patent extracts and eliminates unnecessary components (couplers and variable attenuators) from the DPD calibration path by using direct over-the-air coupling between transmit and receive chains. This removal of components eliminates the insertion loss they would introduce while maintaining calibration capability.
4Reliability
If dedicated calibration chains are used, then DPD calibration can be performed, but simultaneous transmission and reception is limited
Solution Approach 1:
The patent designs communication chains to be universal, capable of performing both regular communication operations and DPD calibration operations. This multi-functionality allows the system to perform simultaneous transmission and reception without being limited by dedicated calibration chains, as the calibration function shares the same infrastructure as regular communication.
Data Source
AI summary
A MIMO transceiver configured for digital pre-distortion may include a first communication chain configured to wirelessly transmit a signal at a first frequency. The first communication chain may include a pre-distorter circuit configured to accept parameters to pre-distort signals prior to transmission. The first communication chain may include a PA configured to amplify the signals of the first communication chain prior to transmission. The MIMO transceiver may include a second communication chain. The second communication chain may be configured to wirelessly receive the signal at the first frequency. The second communication chain may include a converter circuit configured to convert the signal to a baseband frequency. The second communication chain may include a buffer configured to buffer the signal at the baseband frequency. The MIMO transceiver may include a DPD circuit configured to calibrate the parameters based on the buffered signal to compensate for non-linearity in amplification by the PA.