Silicon Discrete Components Application Considerations for the Integrated Bias Control Circuits BCR400R and BCR400W Figure 1 Application Note No. 014 RF Transistor Controlled by BCR400 Operating Point • BCR400 stabilizes the operating current (i.e. IC or ID), the collector (or drain) voltage depends on the supply voltage: VCE = VS - 0.65 V • The voltage drop of approximately 0.65 V on Rext (i.e. between pins 3 and 4 of BCR400) is almost constant (Rext = 0.65 V x IC) • In case a lower VCE is really required (e.g. to prevent exceeding of maximum VCE or VDS ratings), an additional resistor R = (VS - VCE - 0.65 V) / IC can be inserted either between pin 4 and collector (or drain) or in series to the supply voltage VS, thus providing an additional voltage drop. Application Note 1 2000-07-27 Application Considerations for the Integrated Bias Control Circuits BCR400R and BCR400W Stability BCR400 stabilizes bias current of transistors in an active control loop. In order to avoid loop oscillation (hunting), time constants must be chosen adequately, i.e. C1 >= 10 x C2. It is strongly recommended that the entire DC circuit is analyzed and optimized for stability with one of the commercially available SPICE simulators. Thermal considerations The collector or drain current of a stabilized RF transistor does not directly affect BCR400, as it must only provide the base current (or gate bias current). Even as a standalone current source it is not possible to exceed Ptot (up to Ts = 115°C), if the maximum ratings of Vs and Icontr are adhered to (see data sheet). Preliminary SPICE Parameters ***************************************************************** .MODEL DI400 D( + IS= 6.00E-15 N= 1.20E+00 RS= 5.0E+01 + IBV= 1.00E-04 BV= 7.50E+01 + M= 1.00E-01 CJO= 6.87E-13 EG= 1.11E+00 + TT= 8.66E-09 VJ= 2.00E+00 XTI= 5.00E+00) * one internal Diode of BCR400 ***************************************************************** .MODEL TR400 PNP( + BF= 3.00E+02 BR= 3.38E+00 CJC= 2.00E-12 + CJE= 1.56E-11 CJS= 0.00E+00 EG= 1.11E+00 FC= 8.28E-01 + IKF= 1.00E-02 IKR= 0.40E-02 IRB= 0.30E-06 IS= 0.30E-14 + ISC= 2.00E-14 ISE= 0.50E-13 ITF= 0.50E-01 + MJC= 3.49E-01 MJE= 4.18E-01 MJS= 3.30E-01 NC= 1.19E+00 + NE= 1.83E+00 NF= 1.00E+00 NR= 1.00E+00 PTF= 0.00E+00 + RB= 1.00E+02 RBM= 1.00E+01 RC= 5.00E+00 RE= 2.00E-01 + TF= 6.05E-10 TR= 0.00E+00 VAF= 5.90E+01 VAR= 1.74E+01 + VJC= 3.00E-01 VJE= 8.00E-01 VJS= 7.50E-01 VTF= 4.39E+00 + XCJC= 1.00E+00 XTB= 0.00E+00 XTF= 5.81E+00 XTI= 1.50E+00) ***************************************************************** * internal parallel resistance Rint= 6.5 kOhm * Rb= 75 kOhm ***************************************************************** Application Note 2 2000-07-27 Application Considerations for the Integrated Bias Control Circuits BCR400R and BCR400W Revision History: 2000-07-27 DS0 Previous Version: Page Subjects (major changes since last revision) Document’s layout has been changed: 2002-Aug. For questions on technology, delivery and prices please contact the Infineon Technologies Offices in Germany or the Infineon Technologies Companies and Representatives worldwide: see our webpage at http://www.infineon.com. Edition 2000-07-27 Published by Infineon Technologies AG, St.-Martin-Strasse 53, 81669 München, Germany © Infineon Technologies AG 2002. All Rights Reserved. Attention please! The information herein is given to describe certain components and shall not be considered as warranted characteristics. Terms of delivery and rights to technical change reserved. We hereby disclaim any and all warranties, including but not limited to warranties of non-infringement, regarding circuits, descriptions and charts stated herein. Infineon Technologies is an approved CECC manufacturer. Information For further information on technology, delivery terms and conditions and prices please contact your nearest Infineon Technologies Office in Germany or our Infineon Technologies Representatives worldwide. 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.