Stacked Wideband RF Amplifiers for Lower DC Power
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Solution Overview
Problem
Current RF communication system components, such as local oscillator amplifiers, face challenges with high parasitic capacitance, limited frequency range operation, and high DC power consumption, which hinder the production of voltage waveforms with sharp risetimes and efficient frequency operation.
Innovation Solution
The use of stacked amplifiers connected between a DC voltage source and ground, which reuse DC current and divide the supply voltage equally between modules, allowing for reduced DC current consumption and higher frequency operation, along with inverter amplifiers and self-bias circuits to stabilize the DC operating point and achieve proportional voltage division.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional RF amplifier components are used, then voltage waveforms can be produced, but the operation frequency range is limited and DC power consumption is high
Solution Approach 1:
The amplifier is divided into multiple stacked amplifier stages (first amplifier, second amplifier, third amplifier, etc.) connected in series between the DC voltage source and ground. Each amplifier stage handles a portion of the total voltage range, enabling the system to operate over a wide frequency range while each individual stage consumes less DC power. The segmentation allows parallel operation of multiple amplifier stages, each optimized for specific frequency bands.
Solution Approach 2:
The invention changes the operating parameters of the amplifier by dividing the DC supply voltage into multiple levels across different amplifier stages. Each amplifier operates at a different voltage level (e.g., first amplifier at higher voltage, second amplifier at intermediate voltage, third amplifier at lower voltage), which enables wideband operation. This parameter division allows the system to achieve wide frequency range while maintaining low DC power consumption at each stage.
2Object-affected harmful factors
If larger geometry components are used to reduce parasitic capacitance, then parasitic effects are reduced, but operation speed becomes slower
Solution Approach 1:
The amplifier circuit is segmented into multiple stages with progressively smaller geometries. The first amplifier stage uses larger geometry devices to handle high-frequency signals with reduced parasitic effects, while subsequent stages use smaller geometry devices for further signal amplification. This segmentation allows the system to maintain high operation speed while managing parasitic capacitance effectively at each stage.
Solution Approach 2:
Different amplifier stages are designed with different local qualities - specifically, different device geometries optimized for their specific functions. The first amplifier stage uses larger geometry transistors to minimize parasitic capacitance effects, while later stages use smaller geometry transistors. This local optimization of device geometry allows each stage to operate at optimal speed while managing parasitic effects appropriately for its function in the signal chain.
3Power
If large DC currents are used to drive RF components, then sufficient drive capability is achieved, but power consumption increases
Solution Approach 1:
The total DC current requirement is segmented across multiple amplifier stages. Each amplifier stage draws a portion of the total DC current from the voltage source, with the current being reused and recycled through the stacked configuration. This segmentation enables the system to achieve sufficient overall drive capability while each individual stage operates at lower current levels, reducing total power consumption.
Solution Approach 2:
Multiple amplifier stages are merged into a single stacked configuration where they share common DC current paths. The DC current flows through multiple amplifiers in sequence, and the configuration allows current recycling where the output of one stage feeds into the next, merging their functions into a unified power-efficient structure. This merging enables sufficient drive capability to be achieved through cumulative effect rather than requiring large current at a single stage.
4Power
If reactive matching techniques with LC tank circuits are used, then large voltage swing is achieved, but the amplifier cannot operate over a wide frequency range with reasonable DC power consumption
Solution Approach 1:
Instead of using a single LC tank circuit for voltage swing amplification, the invention segments the amplification function across multiple amplifier stages. Each stage contributes to the overall voltage swing through its own amplification action, eliminating the need for frequency-tuned LC resonant circuits. This segmentation allows the system to achieve large voltage swing while operating over a wide frequency range without being constrained by the resonant frequency of any single LC tank.
Solution Approach 2:
The invention extracts and removes the LC tank circuit reactive matching element from the amplifier design. By eliminating the frequency-selective LC resonant circuit, the amplifier is freed from frequency constraints and can operate over a wide bandwidth. The voltage swing functionality previously provided by the LC tank is replaced by the cascaded amplification action of multiple amplifier stages, achieving both wide frequency range and sufficient voltage swing.
Data Source
AI summary
A device for amplifying signals over a wide frequency range features stacked amplifying modules connected between a DC voltage source and an electrical ground. The stacking configuration reuses the DC current produced the voltage source, and thus reduces the amount of operational DC current permitting the use of lower voltage, higher frequency devices to be used. The amplifying modules are fed signals which are different versions of an input signal, and the output signals are AC coupled using capacitors to balance out gain imbalances and asymmetries between the amplifying modules.