The ZNBG series of devices are designed to meet the bias requirements of GaAs and HEMT FETs commonly used in satellite receiver LNBs, PMR, cellular telephones etc. with a minimum of external components.
With the addition of two capacitors and a resistor the devices provide drain voltage and current control for 2 external grounded source FETs, generating the regulated negative rail required for FET gate biasing whilst operating from a single supply. This negative bias, at -3 volts, can also be used to supply other external circuits.
The ZNBG2000/1 contains two bias stages. A single resistor allows FET drain current to be set to the desired level. The series also offers the choice of drain voltage to be set for the FETs, the ZNBG2000 gives 2.2 volts drain whilst the ZNBG2001 gives 2 volts.
These devices are unconditionally stable over the full working temperature with the FETs in place, subject to the inclusion of the recommended gate and drain capacitors. These ensure RF stability and minimal injected noise.
complement of FET bias controls, unused drain and gate connections can be left open circuit without affecting operation of the remaining bias circuits.
In order 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 the range -3.5V to 0.7V. 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.
The ZNBG2000/1 are available in MSOP10 packages for the minimum in devices size. Device operating temerature is -40 to 80°C to suit a wide range of environmental conditions.
Required Field 
