Wireless Transmitter Gain Control Using Segmented RF Signal Paths
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Solution Overview
Problem
Current wireless transmitters face challenges in finely controlling signal gain while minimizing current consumption and reducing noise, particularly in achieving the required dynamic range over 80 dB, which degrades reception sensitivity and increases current consumption due to the need for multiple SAW filters and multi-stage amplifiers.
Innovation Solution
The solution involves a wireless transmitter apparatus and method that uses multiple signal processing paths with separate mixers and amplifiers, allowing for selective activation of paths based on output levels to control signal gain, thereby reducing leakage signals and current consumption, and optimizing noise characteristics for different output levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple amplifier elements are combined in parallel to provide required gain, then the dynamic range can be achieved, but leakage signals increase and affect low-level output accuracy
Solution Approach 1:
The transmitter is divided into multiple independent signal paths (first path with first mixer, second path with second mixer), each handling different output levels. This segmentation prevents leakage signals from affecting low-level outputs while maintaining gain control accuracy across the full dynamic range.
Solution Approach 2:
Separate mixers are introduced as intermediary components for different signal paths. Each mixer independently processes signals for specific output levels, acting as a mediator that prevents direct interference and leakage between parallel amplifier elements, thereby improving output accuracy.
2Object-affected harmful factors
If multiple SAW filters are used to reject receive band noise, then noise rejection improves, but current consumption and device area increase
Solution Approach 1:
The patent extracts and removes the SAW filter component from the system, replacing it with a noiseless mixer architecture. By taking out the harmful filtering approach and substituting it with inherent noiseless mixing, receive band noise is rejected without the current consumption and area penalties of multiple SAW filters.
3Object-affected harmful factors
If multiple SAW filters are used to reject receive band noise, then noise rejection improves, but device area and BOM increase
Solution Approach 1:
The patent extracts and removes the SAW filter component from the system, replacing it with a noiseless mixer architecture. By taking out the harmful filtering approach and substituting it with inherent noiseless mixing, receive band noise is rejected without the current consumption and area penalties of multiple SAW filters.
4Manufacturing precision
If multi-stage RF VGA structure is used to process dynamic range over 60 dB, then gain dynamic range is achieved, but noise at transmit output stage increases
Solution Approach 1:
The gain control is segmented into multiple independent paths, each optimized for specific output levels. This segmentation allows dynamic range to be achieved without cascading amplifiers, as each path independently handles its designated range without accumulating noise from multiple stages.
Solution Approach 2:
The system dynamically selects which signal path to use based on the required output level. By dynamically switching between paths rather than using fixed multi-stage amplification, the system achieves wide dynamic range while avoiding the noise accumulation inherent in cascaded amplifier structures.
Data Source
AI summary
To control a gain of a transmit signal in a wireless transmitter, the wireless transmitter is provided. The wireless transmitter includes a baseband processor for processing an analog baseband transmit signal, and a Radio Frequency (RF) signal processor including a plurality of mixers. The plurality of mixers are configured to share an output signal of the baseband processor as an input.