Download BDTIC www.BDTIC.com/infineon Application Note No. 064

A pp l ic a t io n N o t e, R e v . 2. 0 , J a n. 2 00 7
A p p li c a t i o n N o t e N o . 0 6 4
U s i n g th e B C R 4 1 0 W B i a s C on t r o l l er w i th B F P 4 0 5
in Amplifier Circuits
BDTIC
R F & P r o t e c ti o n D e v i c e s
www.BDTIC.com/infineon
BDTIC
Edition 2007-01-09
Published by
Infineon Technologies AG
81726 München, Germany
© Infineon Technologies AG 2009.
All Rights Reserved.
LEGAL DISCLAIMER
THE INFORMATION GIVEN IN THIS APPLICATION NOTE IS GIVEN AS A HINT FOR THE IMPLEMENTATION
OF THE INFINEON TECHNOLOGIES COMPONENT ONLY AND SHALL NOT BE REGARDED AS ANY
DESCRIPTION OR WARRANTY OF A CERTAIN FUNCTIONALITY, CONDITION OR QUALITY OF THE
INFINEON TECHNOLOGIES COMPONENT. THE RECIPIENT OF THIS APPLICATION NOTE MUST VERIFY
ANY FUNCTION DESCRIBED HEREIN IN THE REAL APPLICATION. INFINEON TECHNOLOGIES HEREBY
DISCLAIMS ANY AND ALL WARRANTIES AND LIABILITIES OF ANY KIND (INCLUDING WITHOUT
LIMITATION WARRANTIES OF NON-INFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS OF ANY
THIRD PARTY) WITH RESPECT TO ANY AND ALL INFORMATION GIVEN IN THIS APPLICATION NOTE.
Information
For further information on technology, delivery terms and conditions and prices please contact your nearest
Infineon Technologies Office (www.infineon.com).
Warnings
Due to technical requirements components may contain dangerous substances. For information on the types in
question please contact your nearest Infineon Technologies Office.
Infineon Technologies Components may only be used in life-support devices or systems with the express written
approval of Infineon Technologies, if a failure of such components can reasonably be expected to cause the failure
of that life-support device or system, or to affect the safety or effectiveness of that device or system. Life support
devices or systems are intended to be implanted in the human body, or to support and/or maintain and sustain
and/or protect human life. If they fail, it is reasonable to assume that the health of the user or other persons may
be endangered.
www.BDTIC.com/infineon
Application Note No. 064
Application Note No. 064
Revision History: 2007-01-09, Rev. 2.0
Previous Version: 2000-02-03
Page
Subjects (major changes since last revision)
All
Document layout change
BDTIC
Trademarks
SIEGET® is a registered trademark of Infineon Technologies AG.
Application Note
3
www.BDTIC.com/infineon
Rev. 2.0, 2007-01-09
Application Note No. 064
Using the BCR410W Bias Controller with BFP405 in Amplifier Circuits
1
Using the BCR410W Bias Controller with BFP405 in Amplifier
Circuits
Features
• Bias controller for RF transistors
• Stabilizes collector current
• Low voltage drop (110 mV @ IC = 10 mA)
• Works from 1.8 V supply voltage on
• Unconditionally stable control for many applications
• Small outline SOT343 package
Applications
Amplifier applications for cellular phones, cordless phones, PCS,
DECT, W/LANs, PHS, GMS 1800, RF modems and others.
3
2
BDTIC
4
1
AN064_Pin_connection.vsd
Figure 1
PIN configuration
1.1
Introduction
Low supply voltages in mobile electronic devices increasingly jeopardize your efforts to supply your RF amplifiers
with stable bias current. Most of the commonly known circuits cause a substantial voltage drop and hence reduce
the already low supply voltage budget. BCR410W was designed to reduce the voltage drop to a minimum and to
avoid control oscillations. This application note describes an amplifier circuit with BFP405, but should be easily
applicable to other types of transistors.
1.2
Description
The BCR410W homes an internal voltage reference that supplies a voltage of 85 mV. This voltage Vref is
connected to the positive supply voltage. The Input Signal Vin is compared to Vref and controls the output current
Iout. Figure 2 shows the typical application circuit.
1.3
Realisation
Transistor T1 is BFP405. Rext was dimensioned to 11 Ω. This results in a collector current of 10 mA in T1. C1 and
C2 are dimensioned to be RF-short circuits to block out the RF signals from the DC path. Their value is not critical
for DC biasing considerations. Capacitors C3 and C4 are dimensioned to decouple the RF signal. The datasheet
of BCR410W gives you the details of how to dimension Rext. In this application there is a voltage drop of 110 mA
in the collector path of the RF transistor. Due to internal feedback, this voltage increases for lower collector
currents. Figure 3 shows the gain versus frequency.
Application Note
4
www.BDTIC.com/infineon
Rev. 2.0, 2007-01-09
Application Note No. 064
Using the BCR410W Bias Controller with BFP405 in Amplifier Circuits
VS
V1: BCR410W
C1
= Vref
Rext
+
Lc
C2
BDTIC
R
b
RFin
C4
C3
RFout
T1
AN064_Application_circuit.vsd
Figure 2
Application circuit diagram
S21 Magnitude
30
25
|S21| / dB
20
15
10
5
0
0,5
1
1,5
2
2,5
f / GHz
A N064_Frequency_response.vsd
Figure 3
Frequency response
The passive components are 0402 sized standard devices. The PCB is FR4, 0.5 mm. To facilitate measurement,
the sense terminal of the BCR410W is connected to a pin near the supply connector. Figure 5 displays the
position of the various components.
Application Note
5
www.BDTIC.com/infineon
Rev. 2.0, 2007-01-09
Application Note No. 064
Using the BCR410W Bias Controller with BFP405 in Amplifier Circuits
BDTIC
AN064_Application_Board_layout.vsd
Figure 4
Application Board Layout (actual size: 20 mm x 20 mm)
GND
Vs
Vs
Sense
C1
C2
Rext
V1
RF in
R6
Lc
C4
RF out
T1
C3
AN064_Component_Placement.vsd
Figure 5
Component Placement
Table 1
List of components
Name
Value
Unit
Package
Function
C1
150
pF
0402
DC block
C2
150
pF
0402
DC block
C3
150
pF
0402
RF decoupling
C4
150
pF
0402
RF decoupling
Lc
100
nH
0402
RF choke
Rext
11
Ω
0402
Sense Resistor
Rb
1.0
kΩ
0402
Base Resistor
Application Note
6
www.BDTIC.com/infineon
Rev. 2.0, 2007-01-09
Application Note No. 064
Using the BCR410W Bias Controller with BFP405 in Amplifier Circuits
Table 1
List of components (cont’d)
Name
Value
T1
V1
Unit
Package
Function
BFP405
SOT343
RF Transistor
BCR410W
SOT343
Bias controller
BDTIC
Application Note
7
www.BDTIC.com/infineon
Rev. 2.0, 2007-01-09