Stacked RF Amplifier Gate Biasing for Low-Power Standby Recovery
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Solution Overview
Problem
Existing stacked transistor amplifiers face challenges in maintaining voltage compliance and reducing power consumption during standby mode, while ensuring fast recovery to active mode and minimizing RF signal coupling to the biasing circuit.
Innovation Solution
The proposed solution involves a circuital arrangement with a replica circuit that adjusts its operation between active and standby modes by controlling the input gate biasing voltage and impedance presented to the transistors, ensuring voltage compliance and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the biasing circuit operates in standby mode with reduced power consumption, then power consumption is reduced, but the recovery speed of biasing voltages to active mode decreases
Solution Approach 1:
The biasing circuit maintains a preliminary voltage condition on the gate of the input transistor during standby mode, pre-charging the gate to a voltage close to the active mode operating point. This preliminary action reduces the time required for voltage recovery when transitioning to active mode, while still allowing significant power savings compared to fully active operation.
Solution Approach 2:
The biasing circuit dynamically adjusts its operation between standby and active modes, transitioning the impedance presented to the gate from a high-impedance standby state to a low-impedance active state. This dynamic switching allows the circuit to optimize between power consumption and recovery speed based on operational requirements.
2Speed
If the impedance presented to the gate of the input transistor is reduced for fast recovery, then recovery speed improves, but power consumption during standby mode increases
Solution Approach 1:
The gate is pre-charged to a voltage close to the active mode operating point during standby mode through a controlled current path. This preliminary voltage establishment reduces the recovery time when transitioning to active mode without requiring the gate to be continuously held at full active voltage, thereby reducing standby power consumption.
Solution Approach 2:
The biasing circuit changes the voltage parameter on the gate from a standby voltage level to an active voltage level during mode transitions. By carefully selecting the standby voltage level and the charging current magnitude, the circuit achieves fast recovery while minimizing the power consumed during standby operation.
3Reliability
If replica circuits are used to generate biasing voltages, then voltage compliance is maintained, but power consumption during standby mode increases
Solution Approach 1:
The patent extracts only the essential function of the replica circuit - generating the gate bias voltage - while removing unnecessary power-consuming elements. During standby mode, the replica circuit is modified to present a high impedance and consume minimal power, yet still maintain the voltage compliance function when needed.
Solution Approach 2:
The replica circuit dynamically switches between a low-power standby configuration and a full-power active configuration. During standby, it maintains voltage compliance capability with minimal power consumption by using high-impedance paths. When transitioning to active mode, it quickly switches to low-impedance paths that can supply the required bias current without significant delay.
Data Source
AI summary
Various methods and circuital arrangements for biasing one or more gates of stacked transistors of an amplifier are possible where the amplifier is configured to operate in at least an active mode and a standby mode. Circuital arrangements can reduce bias circuit standby current during operation in the standby mode while allowing a quick recovery to normal operating conditions of the amplifier. Biasing an input transistor of the stacked transistors can be obtained by using a replica stack circuit.