znbg3110 Zetex Semiconductors plc., znbg3110 Datasheet - Page 10

• Manufacturer Part Number: znbg3110
• Description: Fet Bias Controller With Polarisation Switch And Tone Detection
• Manufacturer: Zetex Semiconductors plc.

For many LNB applications tone detection and band switching is required. The ZNBG3110/11
includes the circuitry necessary to detect the presence of a 22kHz tone modulated on the supply
input to the LNB. Referring to the following schematic diagram, the main elements of this detector
are an op-amp enabling the construction of a Sallen Key filter, a rectifier/smoother and a
comparator. Full control is given over the centre frequency and bandwidth of the filter by the
selection of two external resistors and capacitors (one of these resistors, R2, shares the function
of overvoltage protection of pin V
components.
ZNBG3110
ZNBG3111
POL
). The rectifier and comparator circuits utilise no external
4-132