ZNBG3000Q16

FET BIAS CONTROLLER ISSUE 1- AUGUST 1998 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, 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 3 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 ZNBG3000/1 contains three 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 ZNBG3000 gives 2.2 volts drain whilst the ZNBG3001 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. ZNBG3000 ZNBG3001 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. 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 ...