ZNBG3114
DESCRIPTION
The ZNBG series of devices are designed to meet the bias requirements of Ga As and HEMT FETs monly used in satellite receiver LNBs, PMR cellular telephones etc. with a minimum of external ponents. With the addition of two capacitors and a resistor the devices provide drain voltage and current control for three 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 ZNBG3113/14 includes bias circuits to drive up to three external FETs. A control input to the device selects either one of two FETs as operational, the third FET is p e r m a n e n t l y a ct i v e . T hi s f e a t u r e i s particularly used as an LNB polarisation switch. Also specific to LNB applications is the 22k Hz tone detection and logic output feature which is used to enable high and low band frequency switching. The facility to control...
