{
  "patent_number": "US 8847689",
  "country": "US",
  "title": "How Diodes Make Wireless Amplifiers Clearer",
  "original_title": "Stacked amplifier with diode-based biasing",
  "summary": "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.",
  "what_it_does": "This patent describes an amplifier, such as a power amplifier for radio signals (claim 15), that uses several transistors connected in a 'stack' (claim 1). A key component is at least one diode connected in series to a 'gate' of a transistor in this stack (claim 1). This diode provides a 'variable bias voltage' to the transistor. When the amplifier receives a strong input signal (high input power), the diode's voltage drop decreases, which in turn provides a higher bias voltage to the associated transistor (claim 4). This higher bias voltage makes the transistor have 'higher gain' (claim 5), helping the amplifier produce a clearer, more accurate output signal and improving its 'linearity'. For example, this could help a smartphone transmit a clearer signal even when its amplifier is working hard.",
  "what_it_does_not_cover": [
    "Amplifiers that do not use transistors arranged in a 'stack' configuration as described in claim 1.",
    "Biasing methods that do not involve a diode providing a variable bias voltage to a transistor in the stack (claim 1).",
    "Diodes that do not specifically exhibit a lower voltage drop at high input power, leading to a higher bias voltage (claim 4).",
    "Amplifiers where the variable bias voltage does not result in higher gain for the associated transistor at high input power (claim 5).",
    "Amplifiers where the diode is not coupled in series to a gate of at least one transistor in the stack (claim 1)."
  ],
  "filed": "2010-02-24",
  "granted": "2014-09-30",
  "expires": "2030-02-24",
  "status": "active",
  "holder": "Qualcomm",
  "holder_url": "https://patentbrief.org/company/qualcomm",
  "inventors": [
    {
      "name": "Nathan M. Pletcher",
      "url": "https://patentbrief.org/inventor/nathan-m-pletcher"
    },
    {
      "name": "Yu Zhao",
      "url": "https://patentbrief.org/inventor/yu-zhao"
    }
  ],
  "times_cited": 18,
  "tags": [
    "consumer_electronics",
    "telecommunications",
    "semiconductors"
  ],
  "abstract": "Techniques for improving linearity of amplifiers are described. In an exemplary design, an amplifier (e.g., a power amplifier) may include a plurality of transistors coupled in a stack and at least one diode. The plurality of transistors may receive and amplify an input signal and provide an output signal. The at least one diode may be operatively coupled to at least one transistor in the stack. Each diode may provide a variable bias voltage to an associated transistor in the stack. Each diode may have a lower voltage drop across the diode at high input power and may provide a higher bias voltage to the associated transistor at high input power. The at least one transistor may have higher gain at high input power due to the higher bias voltage from the at least one diode. The higher gain may improve the linearity of the amplifier.",
  "url": "https://patentbrief.org/patent/us/8847689/stacked-amplifier-with-diode-based-biasing",
  "markdown_url": "https://patentbrief.org/patent/us/8847689/stacked-amplifier-with-diode-based-biasing/md",
  "google_patents_url": "https://patents.google.com/patent/US8847689",
  "relatedPatents": [
    {
      "patentNumber": "5757229",
      "countryCode": "US",
      "title": "How a Radio Amplifier Saves Energy by Sharing Work",
      "url": "https://patentbrief.org/patent/us/5757229/bias-circuit-for-a-power-amplifier"
    },
    {
      "patentNumber": "6700444",
      "countryCode": "US",
      "title": "How an RF Amplifier Boosts Signal Power Efficiently",
      "url": "https://patentbrief.org/patent/us/6700444/n-way-rf-power-amplifier-with-increased-backoff-power-and-power-added-efficiency"
    },
    {
      "patentNumber": "8130043",
      "countryCode": "US",
      "title": "How Multi-Stage Power Amplifiers Save Battery Life in Wireless Devices",
      "url": "https://patentbrief.org/patent/us/8130043/multi-stage-power-amplifier-with-enhanced-efficiency"
    },
    {
      "patentNumber": "8269555",
      "countryCode": "US",
      "title": "How to Make Radio Amplifiers More Efficient",
      "url": "https://patentbrief.org/patent/us/8269555/efficient-linear-linc-power-amplifier"
    },
    {
      "patentNumber": "10148229",
      "countryCode": "US",
      "title": "Making Radio Amplifiers More Efficient and Clear with Two Tricks",
      "url": "https://patentbrief.org/patent/us/10148229/pre-distortion-in-rf-path-in-combination-with-shaping-table-in-envelope-path-for"
    }
  ]
}