Bypass Amplifier Cascode Biasing for High-Signal Linearity
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Solution Overview
Problem
In wireless communication amplifiers, when the input signal intensity is high, unexpected conduction can occur across semiconductor junctions during bypass mode, affecting the linearity of the bypass circuit and reducing operational performance.
Innovation Solution
The amplifier design includes a cascode structure with specific transistor configurations and bias circuits that turn off transistors to prevent conduction and increase reverse-bias, ensuring the bypass mode operates without linearity issues by using transistors like N-type MOSFETs and P-type MOSFETs, and bias circuits with diodes to manage voltage and impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the switch is turned off to bypass the amplifier during high input signal intensity, then power consumption is reduced, but unexpected conduction occurs on semiconductor junctions of transistors affecting linearity
Solution Approach 1:
The patent extracts the problematic transistor components (first and second transistors) from the active circuit path by turning them off during bypass mode. This removes the source of unexpected conduction while maintaining the bypass function, thereby preserving linearity without sacrificing power consumption benefits
Solution Approach 2:
The patent applies preliminary reverse-bias to the semiconductor junctions of the transistors before they can conduct unexpectedly. By pre-configuring the bias conditions, the transistor junctions are prevented from entering unintended conduction states, ensuring linearity is maintained during bypass operation
Data Source
AI summary
An amplifier includes an input terminal for receiving an input signal, an output terminal for outputting an output signal, a first transistor, a second transistor having a first terminal coupled to a second terminal of the first transistor, a third transistor having a first terminal coupled to a second terminal of the second transistor, a capacitor coupled between a control terminal and a second terminal of the third transistor, a bias circuit coupled to the first terminal of the third transistor for providing a bias voltage to the third transistor, a fourth transistor having a first terminal coupled to the input terminal and a second terminal coupled to the output terminal for providing a bypass path, and a fifth transistor having a first terminal coupled to the first terminal of the first transistor and a second terminal coupled to the output terminal.