Cascode Power Amplifier With Harmonic Termination for mmWave Gain
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Solution Overview
Problem
In 5G communication systems operating in high frequency bands, existing power amplifiers face challenges with gain reduction, degradation of matching characteristics, and linearity issues due to parasitic capacitance, which affect the overall performance of transmission devices.
Innovation Solution
The proposed solution involves a transmission device with a cascode structure using a common source and common gate amplifier configuration, along with cross-coupled capacitors and shunt inductors to resonate parasitic components and terminate second-order harmonics, thereby enhancing gain, stability, and linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a power amplifier is used in high frequency bands (mmWave) for 5G communication, then data transmission rate is improved, but parasitic capacitance causes gain reduction, matching degradation, and linearity issues
Solution Approach 1:
A termination unit is introduced as an intermediary component between the common source amplifier and common gate amplifier. This termination unit includes a shunt inductor connected to ground that serves as a mediator to resonate and terminate parasitic capacitance and second-order harmonics, thereby improving amplifier performance in high frequency bands without sacrificing data transmission rate
Solution Approach 2:
The patent converts the harmful parasitic capacitance and second-order harmonics into beneficial effects by using a shunt inductor to create resonance at specific frequencies. The parasitic capacitance that causes gain reduction and linearity issues is transformed into a controlled resonant circuit that terminates harmful frequencies while maintaining useful signal amplification in the desired frequency range
2Device complexity
If conventional amplifier structures are used in mmWave frequencies, then device complexity is reduced, but gain, stability, and linearity are degraded due to parasitic capacitance
Solution Approach 1:
The amplifier is segmented into two distinct stages: a common source amplifier stage and a common gate amplifier stage, with a termination unit inserted between them. This segmentation allows each stage to be optimized for specific functions - the common source stage provides voltage gain while the common gate stage provides current gain and output buffering, with the termination unit handling parasitic capacitance compensation. This modular segmentation achieves high performance without excessive overall complexity
Solution Approach 2:
The termination unit acts as an intermediary between the two amplifier stages, providing a simple yet effective solution to parasitic capacitance problems. The shunt inductor connected to ground creates a resonant circuit that terminates harmful frequencies without requiring complex compensation networks, thus maintaining device simplicity while improving gain and linearity
3Device complexity
If parasitic capacitance is not compensated, then device complexity remains low, but second-order harmonics and non-linearity increase
Solution Approach 1:
The shunt inductor in the termination unit creates a resonant circuit that converts harmful second-order harmonics and parasitic capacitance into beneficial frequency-selective termination. The resonant circuit presents a low impedance path to ground at specific harmonic frequencies, effectively filtering and terminating harmful signals while maintaining high impedance at the fundamental frequency for proper signal amplification
Solution Approach 2:
The termination unit utilizes electrical resonance (analogous to mechanical vibration) at specific frequencies to terminate harmful second-order harmonics. The shunt inductor and parasitic capacitance form a resonant circuit that naturally oscillates at harmonic frequencies, creating a low-impedance path that dissipates harmful energy without requiring active control or complex filtering circuits
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 configuration effectively reduces parasitic capacitance and harmonic components, improving the power amplifier's performance in millimeter-wave frequencies by increasing gain, stability, and linearity, and reducing secondary non-linearity feedback.
Implementation Method 1
a shunt inductor... resonating with parasitic capacitance at a fundamental frequency to offset parasitic effects
Implementation Method 2
grounding a second harmonic with respect to the second harmonic frequency to reduce harmonic components of the amplified signal
Data Source
AI summary
Disclosed is a 5G (5th generation) or pre-5G communication system for supporting a data transmission rate higher than that of a 4G (4th generation) communication system such as long-term evolution (LTE). A transmission device comprises: a first amplification unit having a common source structure, including cross coupled capacitors, and amplifying an input signal; a second amplification unit, having a common gate structure, for amplifying a signal output from the first amplification unit; and a first removal unit which is connected to output terminals of the first amplification unit and input terminals of the second amplification unit and which removes at least one portion of second harmonics. The first removal unit can offset, with respect to a fundamental frequency, at least some of parasitic capacitance generated from the output terminals of the first amplification unit and the input terminals of the second amplification unit, and can ground a signal having a secondary harmonic frequency with respect to the secondary harmonic frequency.