Digital Baseband Compensation for IMD in Direct Sampling Receivers
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Solution Overview
Problem
Existing wireless base station receivers face challenges in achieving high linearity due to the interaction between intermodulation distortion (IMD) and harmonic distortion, which complicates distortion analysis and requires sophisticated signal processing techniques, leading to increased power consumption and complexity.
Innovation Solution
A digital non-linearity compensation method is implemented in the digital baseband of a direct sampling basestation receiver, which generates a corrective term to compensate for intermodulated non-linearity without affecting harmonic distortion, thereby reducing power consumption and simplifying the compensation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If analog non-linearity compensation or digital compensation in the RF band is used, then linearity performance is improved, but power consumption increases significantly
Solution Approach 1:
The patent replaces analog non-linearity compensation circuits with digital baseband processing. Specifically, it uses digital signal processing techniques including third-order multiplication of I/Q data and preset non-linearity coefficients to generate corrective terms, substituting complex analog RF band compensation with simpler digital operations that consume less power.
Solution Approach 2:
The patent extracts and compensates only for intermodulated non-linearity components while deliberately excluding harmonic distortion components. By focusing solely on the intermodulated distortion terms and using a low-pass filter to remove harmonic components, the system reduces the complexity and power consumption of the compensation process.
2Reliability
If sophisticated signal processing techniques are implemented to handle both IMD and harmonic distortion, then distortion compensation is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the necessary intermodulated distortion components for compensation while deliberately excluding harmonic distortion components. This selective approach simplifies the signal processing by focusing on the most critical distortion type that affects RF application performance.
Solution Approach 2:
The patent segments the distortion compensation task by separating intermodulated distortion from harmonic distortion. It processes only the intermodulated components through digital baseband operations, while harmonic components are filtered out, thereby dividing the complex compensation problem into manageable parts.
3Measurement precision
If RF ADC with high sampling rate is used, then signal accuracy is improved, but power consumption increases
Solution Approach 1:
The patent replaces high-speed RF analog-to-digital conversion with direct sampling followed by digital baseband processing. By using a lower sampling rate ADC and performing the necessary signal processing in the digital domain with simplified algorithms, the system maintains signal accuracy while significantly reducing the power consumption associated with high-speed RF ADC operation.
Data Source
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AI summary
In some implementations, the circuitry may include a circuit configured to receive a baseband signal, the baseband signal having an intermodulated non-linear distorted portion and a harmonic distorted portion. In addition, the circuitry may include a compensator coupled to the circuit, the compensator configured to generate a value to compensate for the intermodulated non-linear distorted portion without compensating for the harmonic distorted portion. The circuitry may include where the compensator is configured to output the value. The circuitry may include where the circuit is configured to adjust the baseband signal using the value. In some embodiments, the baseband signal can be baseband voltage. In some embodiments, the value can be a complex number.