Envelope Tracker Circuit With Low-Impedance Input for RF Bandwidth
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power amplifiers in RF communication systems face inefficiencies in managing power consumption due to the inability to rapidly adjust voltage levels in response to changing RF signal envelopes, leading to reduced power added efficiency (PAE) and increased heat generation.
Innovation Solution
A high bandwidth envelope tracking system is introduced, featuring a differential amplifier with a low impedance input for the envelope signal, allowing for rapid transient response and dynamic adjustment of the power amplifier supply voltage through a DC-to-DC converter and input current reduction circuit, ensuring the power amplifier supply voltage closely tracks the RF signal envelope.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional power amplifier is used with fixed supply voltage, then the circuit is simple and reliable, but power added efficiency is reduced and heat generation increases
Solution Approach 1:
The patent implements dynamic supply voltage adjustment by introducing an envelope tracking circuit that varies the power amplifier's supply voltage in real-time according to the RF signal envelope. This dynamic voltage modulation allows the amplifier to operate efficiently across different power levels, directly improving power added efficiency while managing the complexity through targeted circuit additions rather than complete system redesign
Solution Approach 2:
The invention changes the supply voltage parameter dynamically to match the envelope of the RF signal. By modulating the supply voltage according to the signal's instantaneous power requirements, the system achieves better efficiency without requiring complete architectural changes to the power amplifier itself
2Speed
If the envelope tracker uses high impedance input for envelope signal, then the circuit is simpler, but the transient response is slow and bandwidth is limited
Solution Approach 1:
The patent inverts the conventional approach by using a low impedance input for the envelope signal instead of the traditional high impedance input. This inversion enables the envelope tracker to source or sink large currents, rapidly charging and discharging internal capacitances to achieve fast transient response and high bandwidth, while the complexity is managed through careful circuit design
3Speed
If the envelope tracker sources or sinks large current, then the transient response is fast, but the power consumption increases
Solution Approach 1:
The patent employs preliminary action by pre-charging internal capacitances during periods when the envelope signal is stable or changing slowly. This preparation allows the envelope tracker to respond more efficiently to sudden envelope changes without requiring continuous high current flow, thereby reducing overall power consumption while maintaining fast transient response capability
Solution Approach 2:
The system uses periodic action through the natural envelope modulation of the RF signal itself, which periodically drives the envelope tracker. This periodic operation allows the circuit to recharge and discharge capacitances in rhythm with the signal envelope, achieving fast response when needed while consuming less power during steady-state operation
Data Source
AI summary
High bandwidth envelope trackers are provided herein. In certain embodiments, an envelope tracking system for a power amplifier includes a switching regulator that operates in combination with a high bandwidth amplifier to generate a power amplifier supply voltage for the power amplifier based on an envelope of a radio frequency (RF) signal amplified by the power amplifier. The high bandwidth amplifier includes an output that generates an output current for adjusting the power amplifier supply voltage, a first input that receives a reference signal, and a second input that receives an envelope signal indicating the envelope of the RF signal. The second input has lower input impedance than the first input to provide a rapid transient response and high envelope tracking bandwidth.