{
  "patent_number": "US 6700444",
  "country": "US",
  "title": "How an RF Amplifier Boosts Signal Power Efficiently",
  "original_title": "N-way RF power amplifier with increased backoff power and power added efficiency",
  "summary": "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.",
  "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)."
  ],
  "filed": "2002-01-28",
  "granted": "2004-03-02",
  "expires": "2022-01-28",
  "status": "expired",
  "holder": "Cree Microwave",
  "holder_url": "https://patentbrief.org/company/cree-microwave",
  "inventors": [
    {
      "name": "Raymond Sydney Pengelly",
      "url": "https://patentbrief.org/inventor/raymond-sydney-pengelly"
    }
  ],
  "times_cited": 21,
  "tags": [
    "telecommunications",
    "consumer_electronics",
    "semiconductors"
  ],
  "abstract": "An RF power amplifier for amplifying an RF signal over a broad range of power with improved efficiency includes a main amplifier for amplifying an RF signal over a first range of power and with a power saturation level below the maximum of the broad range of power. A plurality of auxiliary amplifiers are connected in parallel with the main amplifier with each of the auxiliary amplifiers being biased to sequentially provide an amplified output signal after the main amplifier approaches saturation. The input signal is applied through a signal splitter to the main amplifier and the plurality of auxiliary amplifiers, and an output for receiving amplified output signals from the main amplifier and the plurality of auxiliary amplifiers includes a resistive load R/2. The split input signal is applied through a 90° transformer to the main amplifier, and the outputs of the auxiliary amplifiers are applied through 90° transformers to a output load. When operating below saturation, the main amplifier delivers power to a load of 2R and the main amplifier delivers current to the load which is one-half the current at maximum power and the amplifier is saturated.",
  "url": "https://patentbrief.org/patent/us/6700444/n-way-rf-power-amplifier-with-increased-backoff-power-and-power-added-efficiency",
  "markdown_url": "https://patentbrief.org/patent/us/6700444/n-way-rf-power-amplifier-with-increased-backoff-power-and-power-added-efficiency/md",
  "google_patents_url": "https://patents.google.com/patent/US6700444",
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}