FET BIAS CONTROLLER WITH POLARISATION ZNBG3115 SWITCH AND TONE DETECTION ZNBG3116 ISSUE 2 - JUNE 2006 DEVICE DESCRIPTION The ZNBG series of devices are designed to meet the Drain current setting of the ZNBG3115/16 is user bias requirements of GaAs and HEMT FETs selectable over the range 0 to 15mA, this is achieved commonly used in satellite receiver LNBs, PMR, with addition of a single resistor. The series also offers cellular telephones etc. with a minimum of external the choice of drain voltage to be set for the FETs, the components. 3115 gives 2.2 volts drain whilst the 3116 gives 2 volts. With the addition of two capacitors and a resistor the These devices are unconditionally stable over the full devices provide drain voltage and current control for working temperature with the FETs in place, subject to three external grounded source FETs, generating the inclusion of the recommended gate and drain the regulated negative rail required for FET gate capacitors. These ensure RF stability and minimal biasing whilst operating from a single supply. This injected noise. negative bias, at -2.8 volts, can also be used to It is possible to use less than the devices full supply other external circuits. complement of FET bias controls, unused drain and gate The ZNBG3115/16 includes bias circuits to drive up connections can be left open circuit without affecting to three external FETs. A control input to the device operation of the remaining bias circuits. selects either one of two FETs as operational, the To protect the external FETs the circuits have been third FET is permanently active. This feature is designed to ensure that, under any conditions including normally used as an LNB polarisation switch. Also power up/down transients, the gate drive from the bias specific to Universal LNB applications is the 22kHz circuits cannot exceed the range -3.5V to 1V. tone detection and logic output feature which is Additionally each stage has its own individual current used to enable high and low band frequency limiter. Furthermore if the negative rail experiences a switching. fault condition, such as overload or short circuit, the The ZNBG3115/16 has been designed to cope with drain supply to the FETs will shut down avoiding DiSEqC ready set top boxes and rejects all excessive current flow. transients from channel switching. The ZNBG3115/16 are available in QSOP16 and QSOP20 for the minimum in device size. Device operating temperature is -40 to 80C to suit a wide range of environmental conditions. FEATURES APPLICATIONS Provides bias for GaAs and HEMT FETs Satellite receiver LNBs Drives up to three FETs Private mobile radio (PMR) Dynamic FET protection Cellular telephones Drain current set by external resistor Regulated negative rail generator requires only 2 external capacitors Choice in drain voltage Wide supply voltage range Polarisation switch for LNBs 22kHz tone detection for band switching Tone detector ignores unwanted signals Support fr MIMIC, FET and Bipolar local oscillator devices Compliant with ASTRA control specifications QSOP 16 and 20 surface mount packages ISSUE 2 - JUNE 2006 1ZNBG3115 ZNBG3116 ABSOLUTE MAXIMUM RATINGS Supply Voltage -0.6V to 12V Power Dissipation (T = 25C) amb Supply Current 100mA QSOP16 500mW Input Voltage (V ) 25V Continuous QSOP20 500mW POL Drain Current (per FET) 0 to 15mA (set by R ) CAL Operating Temperature -40 to 80C Storage Temperature -50 to 85C ELECTRICAL CHARACTERISTICS. TEST CONDITIONS (Unless otherwise stated):T = 25C,V =5V,I =10mA (R =33k ) amb CC D CAL LIMITS SYMBOL PARAMETER CONDITIONS UNITS MIN. TYP. MAX. V Supply Voltage 5 10 V CC I Supply Current I =I (or I )=I =0 8.5 15 mA CC D1 D2 D12 D3 I =0, I (or I )=I =10mA, V =14V 28 35 mA D1 D2 D12 D3 POL I =0,I (or I )=I =10mA, V =15.5V 28 35 mA D2 D1 D12 D3 POL I and I =0, I =10mA 18 25 mA D1 D3 LB I and I =0, I =10mA 18 25 mA D1 D3 HB V Substrate Voltage (Internally generated) I =0 -3.05 -2.8 -2.55 V SUB CSUB -2.4 V I =-200 A CSUB Output Noise E Drain Voltage C =4.7nF, C =10nF 0.02 Vpkpk ND G D E Gate Voltage C =4.7nF, C =10nF 0.005 Vpkpk NG G D f Oscillator Frequency 180 330 800 kHz O 2 ISSUE 2 - JUNE 2006