RF Power Detector Circuit With MOS Cancellation for Amplifier Linearity
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Solution Overview
Problem
Designing a satisfactory radio-frequency amplifier for electronic devices with wireless communications capabilities is challenging due to the degradation of amplifier linearity when power detection circuits are coupled to radio-frequency amplifiers.
Innovation Solution
Incorporating non-linearity canceling components, such as metal-oxide-semiconductor (MOS) capacitors, at the input of power detection circuits to mitigate non-linear effects and improve the third-order intercept point (IP3) of radio-frequency amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a power detection circuit is coupled to a radio-frequency amplifier, then power detection capability is achieved, but amplifier linearity is degraded
Solution Approach 1:
A non-linearity cancellation component (MOS capacitor) is introduced as an intermediary element between the power detection circuit and the radio-frequency amplifier. This capacitor generates a canceling current that counteracts the non-linear effects introduced by the power detection circuit, thereby maintaining amplifier linearity while enabling power detection functionality.
Solution Approach 2:
The non-linearity cancellation component performs preliminary anti-action by generating a canceling current before the non-linear distortion affects the amplifier output. This preemptive cancellation prevents the degradation of amplifier linearity that would otherwise occur due to the coupling of the power detection circuit.
2Reliability
If non-linearity canceling components are added to improve amplifier linearity, then third-order intercept point is improved, but device complexity increases
Solution Approach 1:
The non-linearity cancellation component serves multiple functions simultaneously: it acts as a capacitor for signal coupling, generates the canceling current to counteract non-linear effects, and provides biasing for the power detection circuit. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent merges the non-linearity cancellation function with the existing power detection circuit structure by integrating the MOS capacitor into the signal path. This consolidation approach avoids adding completely separate cancellation circuits, thus improving linearity while minimizing the increase in overall device complexity.
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
Enhances the throughput of radio-frequency amplifiers by improving their linearity, thereby maintaining optimal performance in wireless communications.
Implementation Method 1
a non-linearity cancellation component coupled between the input transistor and the biasing circuit. The non-linearity cancellation component can be a metal-oxide-semiconductor (MOS) capacitor
Data Source
AI summary
Wireless circuitry can include a radio-frequency amplifier and a power detection circuit coupled to an output of the radio-frequency amplifier. The power detection circuit can include an input transistor, a biasing circuit configured to output a bias voltage for the input transistor and configured to track temperature and voltage variations, and a non-linearity cancellation component configured to generate a current that at least partially cancels a non-linear current associated with the input transistor. The input transistor may be an n-type transistor, and the non-linearity cancellation component may be a p-type metal-oxide-semiconductor capacitor. The biasing circuit can include n-type and p-type diode-connected bias transistors.