Browse Prior Art Database

Field Effect Transistor Circuits

IP.com Disclosure Number: IPCOM000095546D
Original Publication Date: 1964-Feb-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 3 page(s) / 56K

Publishing Venue

IBM

Related People

Atwood, LW: AUTHOR

Abstract

These circuits use similar conductivity, e. g., PNP or NPN field effect or thin film transistors, to provide various circuit functions. Like conductivity field effect transistors (FET's) can be produced as either enhancement or depletion devices.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 3

Field Effect Transistor Circuits

These circuits use similar conductivity, e. g., PNP or NPN field effect or thin film transistors, to provide various circuit functions. Like conductivity field effect transistors (FET's) can be produced as either enhancement or depletion devices.

An enhancement device is one which is normally off (no) or nonconducting and becomes conductive as the gate is forwardly biased with respect to the source. An exemplary characteristic for an enhancement device is shown at A. By connecting the gate and drain of such a device, a diode-like characteristic 12 is produced.

A depletion device is one which is normally conducting (nc) and continues to conduct until a predetermined back bias is applied. The characteristics for a depletion device are shown at B. Such a device resembles a resistor when its gate electrode is tied to its drain electrode and a constant current source when its gate electrode is tied to its source electrode, as shown by characteristic curves 14 and 16, respectively.

At C, the follower circuit output is always in phase with the input. When the input level is at e1, characteristic curve 18 is established for Q1. Since Q2 has its gate permanently tied to its source, it acts as a constant current device as shown by characteristic 22. Intersection point 20 between characteristics 18 and 22 determines the output potential - e3 when the input is at e1. When the input potential is at e2, characteristic curve 24 is established for Q1 and output potential e4 results.

At D, there is an inverter along with the characteristic curves which describe its operation. Since the gate electrode 26 of Q3 is permanently tied to its source electrode 28, Q3 acts as a constant current source with a characteristic such as shown at 30. Input levels e1 and e2 establish characteristic curves 32 and 34 respectively for Q4. Intersection points 36 and 38 define the output levels e3 and e4 with input levels of e1 and e2 respectively.

At E, the circuit performs a voltage translation function. In this circuit...