ZABG4003
4 STAGE FET LNA BIAS CONTROLLER
Summary
The ZABG4003 is an advanced GaAs and HEMT FETs bias controller designed to operate from minimal supply rails and intended primarily for
satellite Low Noise Blocks (LNBs). With the addition of one capacitor and two resistors, the ZABG4003 provides drain voltage and current control
for up to 4 external grounded source FETs. Generating the regulated negative rail required for FET gate biasing whilst operating from a single
supply of 2.1V to 5V. The -2V negative bias can also be used to supply other external circuits. Setting drain currents on the ZABG4003 uses two
resistors to split control between two pairs of FETs. This allows the operating current of input FETs to be adjusted to minimize noise, whilst the
following FET stages can separately be adjusted for maximum gain.
Features Applications
Provides Bias for up to 4 GaAs and HEMT FETs Low Power LNBs
Operating Range of 2.1V to 5V Digital LNBs
Ultra-low Operating Current of 0.95mA IP LNBs
Dynamic FET Protection Twin LNBs and Quad LNBs
Amplifier FET Drain Current Selectable (4mA to 15mA) General Purpose LNA Bias
Regulated Negative Rail Generator Requires only 1 External
Capacitor
Expended Temperature Range of -40C to +105C
U-QFN3030-16 (Type B) Surface Mount Package
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
ZABG4003
Device Description
The ZABG 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 whilst operating from a minimal voltage supply and using minimal current.
The ZABG4003 has four FET bias stages that can be programmed to provide a constant drain current. Programming of the FET bias stage
arrangement and the operating currents of each FET group is achieved by resistors connected to the R and R pins, allowing input FETs to
CAL1 CAL2
be biased for optimum noise, amplifier FETs for optimum gain. Amplifier FETs can be operated at currents in the range 4 to 15mA. D1 and D3 on
the ZABG4003 can be programmed with R over the range of 4 to 15mA and D2 and D4 are programmed with R .
CAL1 CAL2
Drain voltages of amplifier stages are set at 2.0V and are current limited to approximately current set by their associated R resistors.
CAL
Depletion mode FETs require a negative voltage bias supply when operated in grounded source circuits. The ZABG4003 includes an integrated
switched capacitor DC-DC converter generating a regulated output of -2V to allow single supply operation. The ZABG4003 has been designed to
be used with supply rails of 2.1V to 5.0V and the V range has been extended to 5.5V to allow for 10% supply variation.
DD
It is possible to use less than the 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 -2.5V. 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 be limited, avoiding excessive current flow.
The ZABG4003 is available in the 16 pin U-QFN3030-16 (Type B) package.
Device operating temperature is -40C to +105C to suit a wide range of environmental conditions.
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ZABG4003 December 2016
Diodes Incorporated
www.diodes.com
Document number: DS38915 Rev. 1 - 2
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