Programmable RF Notch Filter for Envelope Tracking Ripple
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Solution Overview
Problem
DC-DC converters often produce undesirable ripple voltage due to switching operations, which current techniques struggle to minimize effectively while maintaining efficiency and cost constraints.
Innovation Solution
A DC-DC converter design incorporating a parallel amplifier and a radio frequency (RF) notch filter, where the RF notch filter is coupled between the parallel amplifier output and ground, allowing for a selectable notch frequency to target specific frequencies and reduce noise, and the parallel amplifier and switching supply work together to provide an envelope power supply signal that partially tracks an RF transmit signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a switching supply is used to provide power to the parallel amplifier, then power efficiency is improved, but ripple voltage is introduced into the output signal
Solution Approach 1:
An RF notch filter is introduced as an intermediary component between the parallel amplifier output and ground. This filter selectively attenuates the ripple voltage at the specific RF frequency without affecting the envelope tracking signal, thereby removing the harmful ripple while preserving the efficient switching supply architecture.
Solution Approach 2:
The notch frequency of the RF filter is programmably tuned to match the specific RF frequency generated by the switching supply. By dynamically adjusting the filter parameter (notch frequency) to match the ripple frequency, the system effectively eliminates ripple voltage while maintaining power efficiency.
2Object-generated harmful factors
If a traditional low-pass filter is used to reduce ripple voltage, then ripple voltage is minimized, but the filter cannot selectively target specific RF frequencies
Solution Approach 1:
The RF notch filter incorporates programmable frequency tuning capability, allowing the notch frequency to be dynamically adjusted based on the specific RF frequency in use. This dynamic adaptability enables selective targeting of ripple voltage at different frequencies while maintaining the ability to pass other frequency components.
Solution Approach 2:
The filter's key parameter (notch frequency) is made programmable and tunable, allowing it to adapt to different RF frequencies. This parameter change capability transforms a static low-pass filter into a dynamic, frequency-selective notch filter that can precisely target and eliminate ripple at the specific RF frequency.
3Device complexity
If the notch frequency is fixed, then the filter design is simpler, but it cannot adapt to different RF duplex frequencies
Solution Approach 1:
The RF notch filter is designed with programmable frequency tuning capability, enabling a single filter circuit to serve multiple frequency bands. This multi-functionality allows the same hardware design to adapt to different RF duplex frequencies (e.g., TDD, FDD, IMT-2000) without requiring separate fixed-frequency filters for each band.
Solution Approach 2:
The filter incorporates dynamic frequency tuning through programmable components, allowing the notch frequency to be adjusted based on the operating mode. This dynamic characteristic enables the filter to adapt to different RF frequencies while maintaining a unified, relatively simple hardware architecture.
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 configuration effectively reduces noise and ripple voltage in RF receive circuitry by selecting a notch frequency aligned with RF duplex frequencies, enhancing the efficiency and accuracy of power supply while minimizing unwanted noise and ripple.
Implementation Method 1
The RF notch filter has a selectable notch frequency, which is based on an RF duplex frequency
Data Source
AI summary
A parallel amplifier, a switching supply, and a radio frequency (RF) notch filter are disclosed. The parallel amplifier has a parallel amplifier output, such that the switching supply is coupled to the parallel amplifier output. Further, the RF notch filter is coupled between the parallel amplifier output and a ground. The RF notch filter has a selectable notch frequency, which is based on an RF duplex frequency.