Cascode Power Amplifier Harmonic Termination for 5G mmWave Gain
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Solution Overview
Problem
Existing power amplifiers in wireless communication systems, particularly in 5G systems operating in high frequency bands, face challenges with reducing harmonic components and parasitic capacitance, which affect gain, stability, and linearity.
Innovation Solution
A transmission device employing a differential cascode amplifier structure with cross-coupled capacitors and a harmonic termination unit comprising inductors and capacitors to terminate second-order harmonics and offset parasitic capacitance, enhancing gain and stability while improving linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If power amplification is performed in high frequency bands (mmWave) for 5G communication, then data transmission rate is improved, but path loss increases and transmission distance decreases
Solution Approach 1:
The amplifier is divided into multiple stages including a driver stage and a final stage, with each stage performing specific functions. The driver stage prepares the signal while the final stage provides power amplification, allowing optimal design for each function separately to overcome high frequency losses.
Solution Approach 2:
Cross-coupling capacitors are used to combine the output signals from parallel amplifying elements. This merging of signals increases the overall output power and improves the signal-to-noise ratio, compensating for path loss in mmWave bands.
2Device complexity
If conventional amplifier structures are used in high frequency bands, then circuit simplicity is maintained, but gain reduction and matching degradation occur
Solution Approach 1:
Different parts of the amplifier circuit are designed with specific characteristics optimized for their function. The driver stage has different component values and topology than the final stage, with each section tailored to its specific role in the signal chain to maintain performance in high frequency bands.
Solution Approach 2:
The amplifier uses dynamic biasing and tuning capabilities to adapt to varying operating conditions in high frequency bands. This allows the circuit to maintain optimal gain and matching across different frequencies and power levels despite the challenging mmWave environment.
3Reliability
If linear amplification is prioritized in power amplifiers, then signal fidelity is improved, but power efficiency deteriorates
Solution Approach 1:
The driver stage provides partial amplification with high linearity to prepare the signal, while the final stage provides excessive power gain with relaxed linearity requirements. This division allows the system to achieve acceptable overall linearity while maximizing power efficiency in the final amplification stage.
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 solution effectively reduces harmonic components and parasitic capacitance, thereby enhancing the overall performance of power amplifiers in millimeter-wave frequencies by resonating parasitic components and terminating second-order harmonics, leading to improved gain, stability, and linearity.
Implementation Method 1
the harmonic termination unit is configured to offset at least a portion of parasitic capacitance generated at the output terminals of the first amplifier and the input terminals of the second amplifier, with respect to a fundamental frequency
Implementation Method 2
to ground a signal having a frequency of the second harmonic, with respect to the frequency of the second harmonic
Data Source
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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.