Charge Pump Boost Converter for Low-Noise RF Power Supply
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Solution Overview
Problem
Traditional boost converters used in Wi-Fi cellular applications suffer from high noise, high ripple, and slow response times, which affect conversion efficiency and are not optimized for high-frequency operations like 5 GHz Wi-Fi transmission.
Innovation Solution
A DC-DC boost converter design incorporating a charge pump with a flying capacitor and power inductor, along with a PWM controller and tracking amplifier, to boost a low battery voltage to a high supply voltage efficiently, reducing noise and ripple through controlled switching and filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a traditional boost converter is used, then the circuit structure is simpler and die size is smaller, but the noise and ripple are high and response time is slow
Solution Approach 1:
The converter is divided into two independent modules: a charge pump circuit for voltage multiplication and a boost converter for current amplification. This segmentation allows each module to be optimized separately, with the charge pump handling voltage boosting without the noise issues of traditional inductor-based converters, while the boost converter provides current amplification with controlled ripple.
Solution Approach 2:
A decoupling capacitor is introduced as an intermediary element between the charge pump output and the boost converter input. This capacitor filters the high-frequency switching noise from the charge pump and provides a stable voltage source for the boost converter, effectively reducing noise and ripple in the overall system.
2Device complexity
If a traditional boost converter is used, then the circuit structure is simpler, but the response time is slow
Solution Approach 1:
By separating the voltage boosting function (charge pump) from the current amplification function (boost converter), the system achieves faster response times. The charge pump can rapidly switch between charging and discharging phases, and the boost converter responds quickly to load changes, overall improving the system's response speed compared to traditional single-stage converters.
Solution Approach 2:
The charge pump operates in periodic charging and discharging phases, allowing it to rapidly transfer energy in discrete packets. This periodic operation enables faster energy delivery to the load compared to continuous operation, improving the overall response time of the power conversion system.
3Adaptability or versatility
If a buck/boost converter is used to convert battery voltage to PA supply voltage, then the voltage conversion is flexible, but the die size is larger and circuit complexity increases
Solution Approach 1:
The converter is divided into two independent modules: a charge pump circuit for voltage multiplication and a boost converter for current amplification. This segmentation allows each module to be optimized separately, with the charge pump handling voltage boosting without the noise issues of traditional inductor-based converters, while the boost converter provides current amplification with controlled ripple.
Solution Approach 2:
The charge pump circuit can operate in multiple modes (charging, discharging, and holding phases) to provide different voltage levels, making it a universal solution for various voltage conversion requirements. The flying capacitor can be charged to different voltage levels by controlling the switch combinations, enabling flexible voltage output without requiring multiple dedicated circuits.
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 effectively boosts a low battery voltage to a high supply voltage with reduced noise and ripple, enhancing conversion efficiency and meeting the power requirements of RF transceivers for high-frequency applications like Wi-Fi, while maintaining a smaller die size and simpler circuit complexity.
Implementation Method 1
the charge pump includes a flying capacitor, a first switch, a second switch, and a third switch, and is configured to provide an interior voltage at the interior node based on the battery voltage. The interior voltage toggles between the battery voltage and two times the battery voltage.
Implementation Method 2
a power inductor coupled between the interior node and a power supply terminal that provides a power voltage to the RF transceiver
Data Source
AI summary
The present disclosure discloses a direct current (DC)-DC boost converter, which includes a battery terminal providing a battery voltage, a charge pump coupled between the battery terminal and an interior node, and a power inductor coupled between the interior node and a power supply terminal that provides a power voltage to a radio frequency transceiver. The charge pump is configured to provide an interior voltage at the interior node based on the battery voltage. Herein, the interior voltage toggles between the battery voltage and two times the battery voltage. The charge pump includes a first switch coupled between the battery terminal and the interior node, a second switch coupled between the battery terminal and a connecting node, a third switch coupled between the connecting node and ground, and a flying capacitor coupled between the interior node and the connecting node of the second switch and the third switch.