Envelope Tracking RF Switch Biasing for Wideband Linearity
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Solution Overview
Problem
Conventional envelope tracking circuits face difficulties in achieving high efficiency and linearity, especially when operating with wide bandwidth signals for multi-channel wireless communication applications, as they struggle to maintain performance in concurrent multi-channel operations with varying bandwidths and high peak-to-average-power ratios.
Innovation Solution
The proposed solution involves an envelope tracking frontend device with a switch that utilizes a CMOS single pole double throw (SPDT) switch configuration, incorporating four transistors with specific gate biasing by an envelope tracking bias supply to modulate signals effectively, and a wideband linear stage to enhance linearity and reduce power consumption, allowing for efficient operation across wide bandwidths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional envelope tracking circuits are used to enhance linearity and efficiency of the power amplifier, then linearity and efficiency are improved, but the circuit cannot operate with signals of wide bandwidths
Solution Approach 1:
The patent applies dynamics by making the bias supply voltage variable and trackable. The envelope tracking circuit dynamically adjusts the bias voltage of the power amplifier in real-time according to the signal envelope, enabling the circuit to adapt to wide bandwidth signals while maintaining high linearity and efficiency. This is achieved through a bias supply voltage generator that produces a tracking voltage based on the envelope of the input signal.
Solution Approach 2:
The patent changes the parameter of bias voltage from fixed to dynamically variable. By modifying the bias voltage parameter to track the signal envelope, the power amplifier can operate efficiently across wide bandwidths. The envelope tracking circuit processes the input signal to extract the envelope and generates a corresponding bias voltage that varies with the signal characteristics.
2Use of energy by moving object
If multipower-mode operation is implemented for high peak-to-average-power ratio signals, then efficiency is improved, but device complexity increases
Solution Approach 1:
The patent implements multipower-mode operation through a dynamic envelope tracking approach. The bias supply voltage generator dynamically adjusts the power amplifier's bias voltage according to the signal envelope, enabling the amplifier to operate in different power modes as needed. This dynamic control achieves high efficiency for high peak-to-average-power ratio signals without requiring complex switching mechanisms or multiple separate circuits.
Data Source
AI summary
An envelope tracking frontend device and a switch thereof are provided. The envelope tracking frontend device includes a power amplifier coupled, a switch and an envelope tracking module including an envelope tracking bias supply coupled between the signal generator and the switch. The switch includes a transmit-receive port, a transmit port coupled to the power amplifier, a receive port, a first terminal and a second terminal in series connection, and a third transistor and a fourth transistor as shunt transistors. The envelope tracking bias supply is configured to provide an envelope forward bias signal to the gate of the second transistor and the gate of the fourth transistor, and provide an envelope reverse bias signal to the gate of the first transistor and the gate of the third transistor such that an amplified signal is modulated before being provided by the switch.