Stacked RF Amplifier Biasing With Replica Stack Standby Voltage
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Solution Overview
Problem
Stacked cascode amplifiers face challenges in maintaining voltage compliance and reducing power consumption during transitions between active and standby modes, with conflicting characteristics in biasing circuits affecting impedance, power consumption, and recovery speed.
Innovation Solution
A circuital arrangement and method using a replica circuit to provide biasing voltages with different characteristics between active and standby modes, involving a reference current source for active mode and a fixed voltage with deactivated current source for standby mode, ensuring voltage compliance and efficient power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a replica circuit is used to generate biasing voltages during active mode, then proper voltage compliance is maintained, but power consumption increases during standby mode
Solution Approach 1:
The biasing circuit dynamically switches between two operational modes: during active mode, the replica circuit operates with the current source enabled to maintain proper voltage compliance; during standby mode, the current source is disabled and a standby voltage is applied to maintain biasing with minimal power consumption. This dynamic adaptation resolves the contradiction between maintaining voltage compliance and reducing power consumption.
2Use of energy by moving object
If the current source is deactivated during standby mode, then power consumption is reduced, but recovery speed of biasing voltages decreases
Solution Approach 1:
During standby mode, the biasing circuit maintains the biasing voltages at a ready state by applying the standby voltage to the replica circuit while keeping the current source disabled. This preliminary action ensures that when transitioning back to active mode, the biasing voltages are already prepared and can recover quickly without requiring full re-establishment, thus maintaining fast recovery speed while minimizing power consumption during standby.
3Reliability
If the replica circuit maintains full biasing characteristics during standby mode, then voltage compliance is ensured, but impedance characteristics deteriorate
Solution Approach 1:
The biasing circuit applies different voltage characteristics to different parts of the replica circuit during standby mode. The standby voltage is applied to maintain proper biasing levels for voltage compliance, while the current source is disabled to alter the impedance characteristics. This local differentiation allows the circuit to maintain voltage compliance without the full biasing characteristics that would degrade impedance performance.
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.