Browse Prior Art Database

A HIGH IMPEDANCE CURRENT SOURCE FOR GaAs MESFET CIRCUITS

IP.com Disclosure Number: IPCOM000007560D
Original Publication Date: 1995-Nov-01
Included in the Prior Art Database: 2002-Apr-05
Document File: 3 page(s) / 110K

Publishing Venue

Motorola

Related People

Joseph Staudinger: AUTHOR [+2]

Abstract

The structure described here is a current source for an integrated MESFET process which provides a high input impedance at microwave frequencies. One application ofthis circuit is a microwave differ- ential amplifier, where the higher impedance leads to improved amplitude balance.

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Technical Developments

A HIGH IMPEDANCE CURRENT SOlJkE

FOR GaAs MESFET CIRCUITS ~

Prior Art #2- MESFET: gate width = 1600 pm, gate length = 1.4 urn, at VGS = 0.

Prior Art #3- MESFET gate width = 2400 pm, gate length = 2.;1 urn, at VGS = 0.

Prior Art #4-Dual gate ~MESFET: gate length =

1200 p, gate length = 0.7 urn, at V~ls = 0, vG2S 7 0.5 v

  Figure 2 illustrates the I-V performance of each device. Figures 3 and 4 illustrates the input imped- ance of each current source. Compared to the other sources, the new current source exhibits much higher impedance levels for frequencies between 1 and 2 GHz. A maximum real impedance of -600 ohms is achieved at a center frequency of 1.5 GHz.

  The peak performance and bandwidth of this new current source can be adjusted by proper selection of inductors Lg and Ls. This circuit is also well suited for higher level current sources where the low out- put conductance of the device Ql can be overcome with proper selection ofinductors Lg and Ls.

by Joseph Staudinger and Joel Birkeland

  The structure described here is a current source for an integrated MESFET process which provides a high input impedance at microwave frequencies. One application ofthis circuit is a microwave differ- ential amplifier, where the higher impedance leads to improved amplitude balance.

  The configuration for the new current source is shown in Figure 1. It consists of a MESFET and two inductors, one inductor attached between the gate of the MESFET and ground, and the other between the source of the MESFET and ground. The inductor Lg forms a series resonant circuit with Cgs, and the inducto...