AN0014 Ver la hoja de datos (PDF) - RF Micro Devices
Número de pieza
componentes Descripción
Lista de partido
AN0014 Datasheet PDF : 4 Pages
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AN0014
Equation 5 may be substituted into Equation 1 and solved for ICC to get:
ICC
=
V----C----C-----–--------δ---δ---V----T----D---------×-----(--T-----–----T----O----)
RBIAS
+
δ-δ---I-V-C--D--C-
Eq. 6
Equation 6 may be differentiated with respect to temperature to get an expression which is useful to observe the effect of
the bias resistor (and supply voltage) selected by the user:
-δ---I--C----C-
δT
=
----------–------δ----δ----V----T---D----------------
RB
I
A
S
+
δ-δ---I-V-C---D-C-
Eq. 7
For example, an NBB-400 biased from a 5V supply (VCC) using a 22Ω resistor (RCC) will exhibit the following current
change with respect to temperature,
-δ---I--C----C-
δT
=
-–---(---–---2---.--8---)-
(22 + 4)
=
0.108mA ⁄ °C
Eq. 8
which translates into a variation of 14mA over the temperature range from -40°C to +85°C. By comparison, if a 12V sup-
ply rail is with a 162Ω bias resistor, then a change in current with respect to temperature reduces to 0.016mA/°C. This
translates into a current variation of only 2.2mA over the same operating temperature range.
15
15-26
Copyright 1997-2002 RF Micro Devices, Inc.
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