# How an RF Amplifier Boosts Signal Power Efficiently > This patent describes an RF power amplifier design that uses a main amplifier and several auxiliary amplifiers to efficiently boost radio signals over a wide power range, especially useful in wireless communication basestations. - **Patent:** US 6700444 - **Original title:** N-way RF power amplifier with increased backoff power and power added efficiency - **Owner:** Cree Microwave - **Granted:** 2004 - **Status:** Public domain (expired) - **Times cited:** 21 - **Field:** telecommunications, consumer_electronics, semiconductors ## What it does This amplifier design boosts radio frequency (RF) signals efficiently across a wide range of power levels. It uses a main amplifier (Claim 1a) to handle lower power signals. When the main amplifier approaches its maximum power output, or 'saturation,' a series of auxiliary amplifiers (Claim 1b) are biased to sequentially turn on, one after another, to continue boosting the signal. An input signal splitter (Claim 1c) directs the signal to both the main and auxiliary amplifiers, with a quarter-wave transformer connected to the main amplifier's input. The amplified signals are then combined at an output, where the auxiliary amplifiers connect through quarter-wave transformers to a specific resistive load (Claim 1d, Claim 5d). For example, a cell tower could use this to amplify a weak incoming signal to a strong, broadcast-ready signal without wasting much energy, even as the required output power changes. ## What it does NOT cover - Amplifiers where auxiliary amplifiers do not turn on *sequentially* after the main amplifier approaches saturation (Claim 1b). - Amplifiers that do not use lateral DMOS transistors for both the main and auxiliary amplifier components (Claim 1a, 1b). - Amplifiers that lack a signal splitter that includes a quarter-wave transformer connected to the input of the main amplifier (Claim 1c). - Amplifiers where the output does not combine signals from main and auxiliary amplifiers, with auxiliary outputs connected through quarter-wave transformers (Claim 1d). - Amplifiers that do not operate over a 'broad range of power' or where the main amplifier's saturation level is not below the maximum of that broad range (Claim 1a). ## The clever bit The novelty lies in the sequential activation of multiple auxiliary amplifiers, each precisely biased to engage only after the main amplifier nears its power limit. This, combined with the strategic use of quarter-wave transformers at both the input and output stages, allows for highly efficient power combining and extended operation over a very wide power range, significantly reducing wasted energy. ## Real-world examples 1. Cellular basestations 2. Radio transmitters 3. Satellite communication systems 4. Wireless network infrastructure 5. High-power radar systems ## Why it matters Efficient RF power amplifiers are crucial for modern wireless communication systems. This design helps reduce energy consumption and heat generation in devices like cell tower basestations, which are always on and handling varying signal loads. By improving efficiency, it helps maintain signal quality and extend the reach of wireless networks while lowering operational costs for telecommunication providers. ## Frequently asked questions ### What does How an RF Amplifier Boosts Signal Power Efficiently cover? This patent describes an RF power amplifier design that uses a main amplifier and several auxiliary amplifiers to efficiently boost radio signals over a wide power range, especially useful in wireless communication basestations. ### Who owns patent US 6700444? Cree Microwave owns this patent, granted in 2004. ### When does this patent expire? This patent has expired and is now in the public domain — anyone can use the invention freely. ### What is patent US 6700444 cited by? This patent has been cited by 21 later patents that build on its ideas. ### What problem does this patent solve? Efficient RF power amplifiers are crucial for modern wireless communication systems. This design helps reduce energy consumption and heat generation in devices like cell tower basestations, which are always on and handling varying signal loads. By improving efficiency, it helps maintain signal quality and extend the reach of wireless networks while lowering operational costs for telecommunication providers. ### What does this patent NOT cover? Amplifiers where auxiliary amplifiers do not turn on *sequentially* after the main amplifier approaches saturation (Claim 1b). **Full plain-English explainer:** https://patentbrief.org/patent/us/6700444/n-way-rf-power-amplifier-with-increased-backoff-power-and-power-added-efficiency **Original patent:** https://patents.google.com/patent/US6700444 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How a Radio Amplifier Saves Energy by Sharing Work](https://patentbrief.org/patent/us/5757229/bias-circuit-for-a-power-amplifier) — This patent describes a power amplifier design that dynamically adjusts the power supplied to two amplifier stages based on the strength of the incoming radio signal, making it more efficient. - [How Multi-Stage Power Amplifiers Save Battery Life in Wireless Devices](https://patentbrief.org/patent/us/8130043/multi-stage-power-amplifier-with-enhanced-efficiency) — This patent describes a clever way for electronic devices, like cell phones, to save battery power by using different amplifier circuits for strong and weak signals, making them more efficient. - [Designing Electronic Networks for Efficient Power Amplification](https://patentbrief.org/patent/us/6552634/wideband-minimum-rating-filters-and-multicouplers-for-power-amplifiers) — This patent describes how to design electronic networks that allow power amplifiers to work efficiently over a wide range of frequencies without overheating or failing. - [How to Make Radio Amplifiers More Efficient](https://patentbrief.org/patent/us/8269555/efficient-linear-linc-power-amplifier) — This patent describes a method for tuning radio frequency power amplifiers to boost their efficiency and maintain a stable signal phase, especially when handling signals with changing loudness and direction. - [How Diodes Make Wireless Amplifiers Clearer](https://patentbrief.org/patent/us/8847689/stacked-amplifier-with-diode-based-biasing) — Qualcomm's patent describes a way to make electronic amplifiers, especially for wireless signals, produce clearer sound by using special diodes to adjust how much power they get based on the signal strength.