RF Switch Transistor Body Connection for Harmonic Suppression
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Solution Overview
Problem
Radio frequency (RF) circuits face performance degradation due to unwanted harmonic signals generated by nonlinear interactions within the circuits, which existing techniques have not adequately addressed.
Innovation Solution
Applying a positive bias body control voltage to switch transistors in RF circuits, specifically greater than 0.7 volts, improves device linearity by mitigating harmonic signals and intermodulation distortion, unlike conventional techniques where the body bias voltage is held at zero volts or allowed to float.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional body bias voltage (zero volts or floating) is used in switch transistors, then device simplicity is maintained, but harmonic signals and intermodulation distortion increase, degrading RF circuit performance
Solution Approach 1:
The patent applies a positive body bias voltage (e.g., +0.7V to +1.5V) to the switch transistor body terminal, changing the electrical parameter of body bias from conventional zero/floating to a controlled positive value. This parameter change modifies the transistor's operating characteristics, reducing nonlinear effects that generate harmonic signals and improving RF circuit performance.
2Object-generated harmful factors
If positive body control voltage is applied to switch transistor body, then harmonic signals are reduced and linearity improves, but device complexity increases due to additional bias control
Solution Approach 1:
The patent employs self-service techniques where the positive body bias voltage is generated and maintained automatically without requiring complex external control circuits. The bias voltage source is designed to provide the required positive voltage level autonomously, reducing the overall device complexity while still achieving the goal of reducing intermodulation distortion and improving linearity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly enhances the linearity of RF circuits by reducing harmonic signals and intermodulation distortion, leading to improved performance, particularly at lower input power levels, with the positive body control voltage effectively limiting body current and reducing harmonic power.
Implementation Method 1
A body control voltage is applied to the body of the switch transistor. The body control voltage is a positive bias voltage when the switch transistor is in an on state. The positive body control voltage effectively limiting body current
Data Source
AI summary
In some method and apparatus embodiments, an RF circuit comprises a switch transistor having a source, a drain, a gate, and a body. A gate control voltage is applied to the gate of the switch transistor. A body control voltage is applied to the body of the switch transistor. The body control voltage is a positive bias voltage when the switch transistor is in an on state. In some embodiments, an RF circuit comprises a control voltage applied to the gate of the switch transistor through a first resistance and applied to the body of the switch transistor through a second resistance. The first resistance is different from the second resistance.