ZABG6002 Datasheet, PDF (8/12 Pages) Diodes Incorporated – LOW POWER 6 STAGE FET LNA AND MIXER BIAS CONTROLLER

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Diodes Incorporated
ZABG6002
This allows the optimization of drain currents for differing tasks such as input stages where noise can be critical and
later amplifier stages where gain may be more important. A graph showing the relationship between the value of
R_CAL and I_D is provided in the Typical Characteristics section of this datasheet. To ensure that the mixer function is
disabled the R_CALM pin should be left open circuit.
ZABG6002 in 4 LNA and 2 active mixer mode
Below is a partial applications circuit for the ZABG6002 showing all external components needed for biasing one of
the four FET stages available for LNA bias and one of the two mixer bias stages. Each LNA bias stage is provided
with a gate and drain pin. The drain pin provides a regulated 2.0V supply that includes a drain current monitor. Each
mixer bias stage is provided with a gate and drain pin. The drain pin provides a regulated 0.3V supply that includes
a drain current monitor but optimized to the requirements of an active mixer. The drain current taken by the external
FET (LNA and Mixer) is compared with a user selected level, generating a signal that adjusts the gate voltage of the
FET to obtain the required drain current. If for any reason, an attempt is made to draw more than the user set drain
current from the drain pin, the drain voltage will be reduced to ensure excess current is not taken. The gate pin
drivers are also current limited.
Vcc
L*
C*
JF2
L*
C1
10nF
D2
G2
D3
G3
RcalM
ZAB G60 02
D5
G5
D6
G6
Rcal1
L*
C3
C*
10nF
VLO
JFM
L*
C*
C2
10nF
* Stripline Elements
CNB
47nF
RCALM
68k
CSUB
47nF
RCAL2
36k
RCAL1
36k
C4
C*
10nF
The bias stages are split up into three groups, with the drain current of each group set by an external R_CAL resistor.
R_CAL1 sets the LNA drain currents of stages 1 and 4 and R_CAL2 sets the drain currents of LNA stages 2 and 5. R_CALM
sets the mixer drain currents of stages 3 and 6. This allows the optimization of drain currents for differing tasks such
as input stages where noise can be critical and later amplifier stages where gain may be more important. A graph
showing the relationship between the value of R_CAL and I_D is provided in the Typical Characteristics section of this
datasheet.
ZABG6002
Document number: DS32078 Rev. 1 - 2
8 of 12
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May 2010
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