The UTC L8115 is 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 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 -2.8 volts, can also be used to supply other external circuits. The UTC L8115 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 permanently active. This feature is normally used as an LNB polarization switch. Also specific to Universal LNB applications is the 22kHz tone detection and logic output feature which is used to enable high and low band frequency switching. |