Diodes ZNBG4003 User Manual
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Description
The ZNBG4003 is a four stage depletion mode FET bias controller
intended primarily for satellite Low Noise Block’s (LNB’s), but its also
suitable for other LNA applications such as those in found in PMR’s
and microwave links. The ZNBG4003 provides each FET with a
negative gate voltage and positive drain voltage with user
programmable drain current.
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ZNBG4003
4 STAGE LNA BIAS CONTROLLER
Pin Assignments
Features
• Four stage FET bias controller
• Operating range of 4.75V to 8.0V
• FET drain voltages set at 2.0V
NEW PRODUCT
• FET drain current selectable from 0 to 15mA
• Allows first and second stage FETs to be run at different
(optimum) drain currents
• FET drain voltages and currents stable over temperature
• FETs protected against overstress during power-up and power-
down.
• Internal negative supply generator allowing single supply
operation (available for external use)
• Low external component count
• Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
• Halogen and Antimony Free. “Green” Device (Note 3)
Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.
2. See http://www.diodes.com for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green" and Lead-free.
3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.
Applications
• Two single type Twin LNB’s
• Twin LNB’s
• Quad LNB’s
• Microwave links
• PMR and Cellular telephone systems
Top view
Bottom view
Twin Universal LNB System Diagram
ZNBG4003
Document number: DS35007 Rev. 1 - 2
1 of 6
www.diodes.com
June 2012
© Diodes Incorporated
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Device Description
The ZNBG series of devices are designed to meet the bias
requirements of GaAs and HEMT FETs commonly used in
satellite receiver LNBs with a minimum of external components.
The ZNBG4003 provides four FET bias stages, arranged in two
pairs of two. Resistors connected to pins R
FET drain currents of each pair over the range of 0 to 15mA,
allowing input FETs to be biased for optimum noise and amplifier
FETs for optimum gain.
Drain voltages of all stages are set at 2.0V. The drain supplies are
current limited to approximately 5% above the operating currents
set by the Rcal resistors.
Depletion mode FETs require a negative voltage bias supply when
operated in grounded source circuits. The ZNBG4003 includes an
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integrated switched capacitor DC-DC converter generating a
regulated output of -2.5V to allow single supply operation.
These devices are unconditionally stable over the full working
temperature with the FETs in place, subject to the inclusion of the
CAL
1 and R
Typical Application Circuit
2 set the
CAL
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ZNBG4003
recommended gate and drain capacitors. These ensure RF
stability and minimal injected noise.
It is possible to use less than the devices full complement of FET
bias controls, unused drain and gate connections can be left open
circuit without affecting operation of the remaining bias circuits.
To protect the external FETs the circuits have been designed to
ensure that, under any conditions including power up/down
transients, the gate drive from the bias circuits cannot exceed -3V.
Additionally each stage has its own individual current limiter.
Furthermore if the negative rail experiences a fault condition, such
as overload or short circuit, the drain supply to the FETs will shut
down avoiding excessive current flow.
To minimise PCB space ZNBG4003 is packaged in the 16 pin
3mm x 3mm QFN package.
Device operating temperature is -40°C to +85°C to suit a wide
range of environmental conditions.
ZNBG4003
Document number: DS35007 Rev. 1 - 2
www.diodes.com
2 of 6
June 2012
© Diodes Incorporated
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