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Número de pieza | AN-0002 | |
Descripción | Biasing Circuits and Considerations | |
Fabricantes | ANADIGICS | |
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Hay una vista previa y un enlace de descarga de AN-0002 (archivo pdf) en la parte inferior de esta página. Total 6 Páginas | ||
No Preview Available ! MESFET Amplifier Biasing
AN-0002
Biasing Circuits and Considerations for
GaAs MESFET Power Amplifiers
Summary
In order to properly use any amplifier it is necessary to provide the correct operating environment,
especially the DC bias. This application note outlines some of the considerations for biasing MESFET
amplifiers. Items considered herein are:
• Constant current operation,
• Temperature compensation of the biasing network, and
• Power sequencing of the applied voltages.
Overview
The I-V curves of Figure 1 represent a typical MESFET device in a common source configuration. For a
typical device operating in Class A the desired current is 50% of the maximum current for any particular
part. Typical MESFET devices are depletion mode, meaning that the highest drain-source current occurs
for a gate voltage of approximately zero (Vgg ~ +0.5 V). As the gate voltage becomes more negative, the
device current drops and eventually approaches zero at the pinch-off voltage. The two main variables in
the production of MESFET power amplifiers are the maximum current and the pinch-off voltage. Since
the operating voltage is assumed to be fixed by the available voltages in the system, it is the drain current
that should be monitored and controlled in order to provide consistent performance from unit to unit.
1.0
m1
0.8
0.6
0.4
0.2
0.0
0
2
m2
46
Vdd
8
m1
Vdd=1.200
Vgg=0.000
Ids.i=0.869
m2
Vdd=7.000
Vgg=-1.100
Ids.i=0.337
10
Figure 1. IV characteristics of a typical MESFET device.
05/2003
http://www.Datasheet4U.com
1 page AN-0002
Table 1. Bill of Materials for Additional Functions Illustrated in Figure 3.
Ref Des
C1, C2, C3
C4
Q1/Q2
Q3
R1
R2
R3
R4
R5
R6
U2
Value
Description
Part No.
Manufacturer Quantity
1 uF 1206, 16 V, low ESR ceramic Cap
EMK316BJ105KF
Taiyo Yuden
3
4.7 uF 1206, 10 V, low ESR ceramic Cap
LMK316BJ475KL
Taiyo Yuden
1
N/A SOT-363, Dual 3906 PNP Transistor
MMDT3906TR-ND Diodes Incorporated 1
N/A HEXFET Power Mosfet, Low On Resistance IRLML6401TR-ND International Rectifier 1
806 ? 0603, 1/16W, 1%
6340 ? 0603, 1/16W, 1%
ERJ-3EKF8060V
ERJ-3EKF6341V
Panasonic
Panasonic
1
1
1.5 ? 2512, 1 W, 5%
909 ? 0603, 1/16W, 1%
ERJ-1TYJ1R5U
ERJ-3EKF9090V
Panasonic
Panasonic
1
1
10 K? 0603, 1/16W, 1%
ERJ-3EKF1002V
Panasonic
1
1 M? 0603, 1/16W, 1%
ERJ-3EKF1004V
Panasonic
1
N/A 10 uMAX, Low -Noise Bias Supply
MAX881REUB
Maxim
1
05/2003
5
5 Page |
Páginas | Total 6 Páginas | |
PDF Descargar | [ Datasheet AN-0002.PDF ] |
Número de pieza | Descripción | Fabricantes |
AN-0001 | Surface Mount Assembly and Handling | ANADIGICS |
AN-0002 | Biasing Circuits and Considerations | ANADIGICS |
AN-0003 | Thermal Considerations | ANADIGICS |
AN-0004 | 12mm Tape | ANADIGICS |
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