RF Power Amplifier MOSCAP Biasing for AM-PM Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Designing a satisfactory radio-frequency power amplifier for electronic devices with wireless communications capabilities is challenging due to amplitude modulation to phase modulation (AMPM) distortion caused by the non-linear input capacitance of power amplifiers.
Innovation Solution
Incorporating an amplitude modulation to phase modulation (AMPM) distortion compensation circuit in the power amplifier, utilizing n-type metal-oxide-semiconductor capacitors (MOSCAPs) that receive a bias voltage to mitigate AMPM distortion by adjusting the operating point of the capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a power amplifier is designed to amplify radio-frequency signals, then the transmission power is increased, but amplitude modulation to phase modulation (AMPM) distortion occurs due to non-linear input capacitance
Solution Approach 1:
The patent introduces n-type MOSCAPs as intermediary elements that mediate between the amplifier output and the input capacitance non-linearity. These capacitors are controlled by bias voltage to dynamically compensate for the non-linear input capacitance effects, thereby reducing AMPM distortion while maintaining high transmission power
Solution Approach 2:
The patent changes the electrical parameters (bias voltage levels) of the MOSCAPs to optimize their capacitance values for compensation. By adjusting the bias voltage, the MOSCAPs can operate at different operating points to provide optimal compensation for AMPM distortion across different signal conditions
2Manufacturing precision
If n-type MOSCAPs are added to compensate for AMPM distortion, then the phase response accuracy is improved, but the device complexity increases
Solution Approach 1:
The MOSCAPs serve multiple functions simultaneously: they provide AMPM distortion compensation, maintain signal amplification, and can be integrated into existing amplifier architectures. This multi-functionality reduces the need for separate compensation circuits, thereby limiting the increase in overall device complexity
3Manufacturing precision
If bias voltage is applied to MOSCAPs to optimize operating point, then the AMPM distortion is reduced, but the energy consumption increases
Solution Approach 1:
The patent applies partial bias voltage to the MOSCAPs, providing just enough compensation to achieve acceptable AMPM distortion reduction without over-biasing the capacitors. This partial action approach optimizes the trade-off between distortion reduction and energy consumption by avoiding excessive bias voltage application
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
The AMPM compensation circuit reduces undesired AMPM distortion, resulting in a more stable output phase response and improved error vector magnitude (EVM) performance.
Implementation Method 1
The compensation circuit may include one or more n-type metal-oxide-semiconductor capacitors (MOSCAPs). The n-type MOSCAPs may be configured to receive a bias voltage at their gate terminals or may be configured to receive a bias voltage at their body terminals.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An electronic device may include wireless circuitry with a processor, a transceiver, an antenna, and a front-end module coupled between the transceiver and the antenna. The front-end module may include one or more power amplifiers for amplifying a signal for transmission through the antenna. A power amplifier (50) may include a phase distortion compensation circuit (58). The phase distortion compensation circuit (58) may include one or more n-type metal-oxide-semiconductor capacitors (N1, N2) configured to receive a bias voltage (Vbias). The bias voltage (Vbias) may be set to provide the proper amount of phase distortion compensation.