Splitter-Driven Push-Pull Power Amplifier for Ripple Suppression
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Solution Overview
Problem
Existing power amplifiers face issues such as high power consumption due to high local oscillator currents, additional component costs from band pass filters, and efficiency loss from IR drops and DC-DC buck ripple, particularly in open-drain and transformer-based push-pull PAs.
Innovation Solution
A splitter-based push-pull PA design using P-type and N-type transistors with a splitter to receive a common-mode input pair, providing differential output pairs to transistor gates, eliminating the need for additional filters and reducing DC current flow to improve efficiency and reduce ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If open-drain power amplifier is used, then power amplification is achieved, but high local oscillator current is required increasing power consumption
Solution Approach 1:
A splitter is introduced as an intermediary component to generate differential drive signals from a single-ended LO signal. This splitter-based architecture enables the push-pull PA to achieve the same power amplification function with lower LO current, thereby reducing power consumption while maintaining the desired output power level.
Solution Approach 2:
The invention changes the operating parameters by transitioning from a single-ended LO drive mode to a differential drive mode using the splitter. This parameter change allows the PA to operate with reduced LO current while achieving the same amplification effect through the differential operation of the push-pull configuration.
2Power
If open-drain power amplifier is used, then power amplification is achieved, but additional band pass filters are required increasing off-chip component cost
Solution Approach 1:
The splitter serves as an intermediary that not only generates differential signals but also inherently suppresses even-order harmonics including the second harmonic distortion. This eliminates the need for additional band pass filters or notch filters, reducing off-chip component requirements and simplifying the overall system architecture.
Solution Approach 2:
The invention converts the potential harmful effect of second harmonic distortion into a beneficial feature by using the splitter's differential output characteristics to naturally suppress even-order harmonics. This transforms what would normally require additional filtering into an inherent advantage of the differential push-pull architecture.
3Power
If output balun with center tap is used, then power amplification is achieved, but large DC current causes large IR drop impacting PA efficiency
Solution Approach 1:
The splitter is introduced as an intermediary that provides differential outputs directly to the push-pull PA stages, eliminating the need for a center-tapped output balun. This removes the source of large DC current flow through the balun, thereby eliminating the IR drop and associated power losses, and improving overall PA efficiency.
4Power
If transformer-based push-pull power amplifier is used, then disadvantages of open-drain PA are overcome, but large DC-DC buck ripple problem occurs
Solution Approach 1:
The invention replaces the transformer-based coupling mechanism with a splitter-based differential signal distribution system. This substitution eliminates the transformer and its associated DC-DC buck ripple problems, while maintaining the push-pull operation benefits. The splitter provides galvanic isolation and differential signaling without the magnetic coupling that causes ripple issues.
Data Source
AI summary
A push-pull power amplifier (PA) includes a pair of P-type transistors, a pair of N-type transistors, and a splitter, wherein source terminals of the pair of P-type transistors are coupled to a first reference voltage, source terminals of the pair of N-type transistors are coupled to a second reference voltage, and drain terminals of the pair of P-type transistors and the pair of N-type transistors are coupled to an output port. The splitter receives a common-mode input pair, and provides two differential output pairs, wherein one of the two differential output pairs is provided to gate terminals of the pair of P-type transistors, and the other of the two differential output pairs is provided to gate terminals of the pair of N-type transistors. A voltage ripple at each of the gate terminals of the pair of P-type transistors is equal to a voltage ripple of the first reference voltage.