The AT1512 includes bias circuits to drive up to 3 external FETs. A control input to the device selects either one of two FETs as operational using 0V gate switching topology, the third FET is permanently active. This feature is particularly used as an LNB polarisation switch. Also specific to LNB applications is the enhanced 22kHz tone detection and logic output feature which is used to enable high and low band frequency switching. The detector has been specifically designed to reject inerference such as low frequency signals and DiSEqCTM tone bursts - without the use of additional external components.