Variable transconductane variable gain amplifier utilizing a degenerated differential pair

{
  "publication_number": "US6744320B2",
  "country": "US",
  "kind": "B2",
  "title": "Variable transconductane variable gain amplifier utilizing a degenerated differential pair",
  "abstract": "Continuously tuning a transconductance. Coupling a degeneration resistance from a first source of a first transistor in a differential pair of transistors to a second source of a second transistor in the differential pair of transistors. Applying a second variable degeneration resistance in parallel to the first degeneration resistance in response to the application of a first variable control voltage. And applying a third variable degeneration resistance in parallel to the first degeneration resistance and the second degeneration resistance in response to the application of a second variable control voltage having a fixed voltage offset from the first variable control voltage.",
  "claims": [
    "1. A variable gain amplifier, comprising: a differentially coupled pair of transistors having a first transistor and a second transistor; a means for applying a degeneration resistance between a source of said first transistor and a source of said second transistor; and a means for distributing said degeneration resistance in a staggered manner, wherein the distortion response of the amplifier is improved and a substantially linear gain is realized.",
    "2. The variable gain amplifier of claim 1, wherein said degeneration resistance comprises a plurality of individual degeneration resistance circuits, coupled in parallel, each having a switch responsive to a control voltage, and a corresponding resistance.",
    "3. The variable gain amplifier of claim 2, wherein said means for distributing comprises applying a plurality of offset control voltages to said switches of said individual degeneration resistance circuits in a staggered fashion.",
    "4. A method for limiting distortion in a variable gain amplifier having a differential transistor pair and a plurality of degeneration resistance circuits coupled in parallel between sources of the transistor pair, the degeneration resistance circuits having a switch responsive to a control voltage and corresponding resistance, comprising: varying the control voltage to stagger turn-on of the degeneration resistance circuits; and selecting the resistances of the degeneration resistance circuits to provide differing degrees of degeneration resistance control."
  ],
  "cpc": [
    "H03F 3/45197",
    "H03F 1/3211",
    "H03F 2200/294",
    "H03F 2200/331",
    "H03F 2200/372",
    "H03G 1/0029"
  ],
  "assignees": [
    "BROADCOM CORP"
  ],
  "filing_date": "2002-12-02",
  "publication_date": "2004-06-01",
  "grant_date": "2004-06-01",
  "priority_date": "2000-02-15",
  "application_number": "US-30729302-A",
  "family_id": "27391570",
  "citations": [
    "EP0587965A1",
    "US3564439A",
    "US3641450A",
    "US4211975A",
    "US5077541A",
    "US5581213A",
    "US5625307A",
    "US5668502A",
    "US5715012A",
    "US5737035A",
    "US5828265A",
    "US6509796B2"
  ]
}