Envelope-Controlled RF Switch Voltage Tracking for Better Linearity
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Solution Overview
Problem
Existing radio frequency communication systems face challenges in efficiently managing power amplifiers and RF switches, particularly in handling varying signal envelopes, which affects power efficiency and signal integrity.
Innovation Solution
A radio frequency switch system incorporating a charge pump to generate regulated voltages based on the signal envelope, a level shifter to control switch voltages, and an envelope tracker to manage power amplifier supply voltages, ensuring the switch control signal aligns with the envelope, thereby optimizing power efficiency and reducing insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a radio frequency switch is controlled by a fixed voltage level, then the circuit design is simple, but power efficiency deteriorates and insertion loss increases when handling varying signal envelopes
Solution Approach 1:
The patent applies dynamics by making the switch control voltage dynamic rather than fixed. A charge pump circuit generates a regulated voltage that tracks the envelope of the RF signal, allowing the switch control voltage to adapt to varying signal conditions. This dynamic adjustment optimizes power efficiency and reduces insertion loss while maintaining manageable circuit complexity through systematic design.
Solution Approach 2:
The patent changes the voltage parameter of the switch control signal from a fixed value to a dynamically regulated value that varies with the signal envelope. The charge pump adjusts the control voltage level based on the envelope detector output, transforming the static parameter into a dynamic one that responds to signal conditions, thereby improving power efficiency without excessive complexity increase.
2Reliability
If the switch control voltage is increased to improve switching performance, then linearity and IIP3 improve, but power consumption increases
Solution Approach 1:
The patent uses dynamics to adjust the switch control voltage based on actual signal conditions. Rather than applying a constantly high voltage to ensure linearity and IIP3, the charge pump generates a regulated voltage that is dynamically adjusted according to the envelope of the RF signal. This ensures adequate switching performance and linearity only when needed, reducing unnecessary power consumption during low-signal conditions.
Solution Approach 2:
The patent implements feedback through an envelope detector that monitors the RF signal and feeds this information to the charge pump. The charge pump uses this feedback to adjust the switch control voltage level, ensuring optimal linearity and IIP3 performance while minimizing power consumption. The feedback loop automatically balances performance requirements with power efficiency based on real-time signal conditions.
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 system enhances power added efficiency, reduces on-state resistance, increases linearity, and improves third-order input intercept point (IIP3) by dynamically controlling switch voltages in response to signal envelopes.
Implementation Method 1
a charge pump configured to generate a regulated voltage based on an envelope signal indicating an envelope of the radio frequency signal
Implementation Method 2
an envelope tracker configured to generate a power amplifier supply voltage of the power amplifier, the envelope tracker configured to control a voltage level of the power amplifier supply voltage based on the envelope signal
Implementation Method 3
a level shifter operable to provide level shifting to an input control signal to generate the switch control signal. The level shifter is configured to control a voltage level of the switch control signal to be about equal to the regulated voltage
Data Source
AI summary
Apparatus and methods for envelope controlled radio frequency (RF) switches are provided. In certain embodiments, a power amplifier provides an RF signal to an antenna by way of an RF switch. Additionally, the envelope signal is used not only to control a power amplifier supply voltage of the power amplifier, but also to control a regulated voltage used to turn on the RF switch. For example, a level shifter can use a regulated voltage from charge pump circuitry to turn on the RF switch, and the envelope signal can be provided to the charge pump circuitry and used to control the voltage level of the regulated voltage over time.