Field-effect transistor with extended linear logarithmic transconductance

• US 4,112,455 A
• Filed: 01/27/1977
• Issued: 09/05/1978
• Est. Priority Date: 01/27/1977
• Status: Expired due to Term

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Seliger, Robert L., Ward, James W.
• Primary Examiner(s): Wojciechowicz, Edward J.
• Application Number:
  US05/763,265
• Time in Patent Office: 586 Days
• Field of Search: 357/22, 357/23, 357/90, 357/91
• US Class Current: 257/335
• CPC Class Codes: H01L 21/265 producing ion implantation
• CPC Class Codes: H01L 21/2654 in AIIIBV compounds
• CPC Class Codes: H01L 29/1041 with a non-uniform doping structure in the channel region surface
• CPC Class Codes: H01L 29/78 with field effect produced by an insulated gate H01L29/7725, H01L29/775, H01L29/778 take precedence

Abstract

The linearity of a field-effect transistor'"'"'s logarithmic transconductance extended over an increased range by having its channel non-uniformly doped in a direction along the width of the gate electrode and perpendicular to that of current flow.

Claims

1. A field-effect transistor of the type having a source region, a drain region and a channel region within which current flow takes place between said source and drain regions

said channel region having a length dimension which is uniform and corresponds to the distance over which said current travels as it flows between said source and drain regions of said transistor and having a width dimension which is perpendicular to said length dimension and to the direction along which said current travels as it flows between said source and drain regions,

said channel region having a non-linear dopant profile along its width dimension which is such that said field-effect transistor exhibits a logarithmic transconductance which is linear with gate signal voltage over an extended range.

2. A method of modifying the performance of an insulated gate field-effect transistor so as to impart to it a logarithmic transconductance versus gate voltage characteristic that is linear over an extended range which comprises the step of

non-linearly doping by an ion implanting process the channel region of said transistor in a direction which is perpendicular to that along which current flow takes place between the source and drain regions of said transistor,

said non-linear doping establishing different current flow and saturation conditions between the source and drain regions along the width of the gate electrode of said transistor.