Device Description
ZNBG series devices are designed to meet the bias requirements of GAAS, HEMT field effect tube receivers LNB, PMR, mobile phones, etc. commonly used in satellites.
At least there are external components.
Together with the two capacitors and resistors that provide the drain voltage and some external current-controlled ground source FETs, the regulated negative rail needed to produce the FET gates is supplied from a single operating bias supply. Negative bias, at -3 volts, can also be used to supply other external device circuits.
ZNBG4000 /1 and ZNBG 6000/1 contain four and six deviation stages respectively. Setting the drain current in the ZNBG4000/1 2 resistors allows separate FET pairs to control different levels of the ZNBG6000/1 2 two and four resistors separately control the FETs. This causes the input FETs to be tuned to minimize noise, and the following FET stages can be individually tuned for maximum gain. The range also offers a choice of drains. voltage to set for the FET
The ZNBG4000/6000 provides a 2.2V drain, while the ZNBG4001/6001 provides 2V. These devices are unconditionally stable over the full operating temperature with the FET in place to contain the recommended gate and drain capacitors. These ensure RF stability and minimal injected noise.
Complementary to device FET bias control that can be used with less than the device full, unused drain and gate connections can remain open.
The circuit does not affect the rest of the bias circuit.
To protect the external FETs, the circuit design ensures that the gate drive bias circuit cannot exceed the -3.5 V range under any conditions, including supply up/down transients. to 0.7V. Also, if the negative rail encounters a fault condition, such as an overload or short circuit, draining the power to the FET will turn off, avoiding excessive current flow.
ZNBG4000/1 and ZNBG6000/1 are available in QSOP16 and 20-pin kits respectively for the smallest device size.
Equipment operating temperature is -40 to 70 ° C to adapt to various environmental conditions.
Features Bias for GaAs and HEMT FETs Drives up to 4 or 6 FETs
Dynamic FET Protection External Resistor Set Leakage Current Regulation Negative Rail Generator Only 2 External Capacitors Drain Voltage Selection Wide Supply Voltage Range Applications Satellite Receivers LNBS
Private Mobile Radio (PMR)
mobile phone

Function description
ZNBG devices provide all biasing requirements for external FETs, including the negative supply needed to generate gate bias, from a single supply voltage.
Single stage of ZNBG series. ZNBG4000/1 contains 4 stages and ZNBG6000/1 contains 6 stages. The negative rail generator is a common part of all devices. The drain voltage of the external FET QN is set by the ZNBG device to its normal operating voltage. This is determined by the onboard VD device reference, for the ZNBG4000/6000 this is typically 2.2 volts, while the ZNBG4001/6001 typically provides 2 volts.
The drain current of the FET is sensed and monitored by a low value resistor ID. The gate of the amplifier drives the FET to adjust the gate voltage of the QN to match the drain current taken.
Current required by external resistor RCal. Both ZNBG devices are programmed with different drain currents into selected FETs. Two RCAL inputs are provided. For ZNBG4000, resistor RCAL1 sets the leakage current of FETs 1 and 2, resistor RCAL2 sets the leakage current of FETs For ZNBG6000, resistor RCAL1 sets the leakage current of FETs 1 and 4, and resistor RCAL2 sets the leakage current of FETs 2, 3, 5 and 6 leakage current.
Since the FET is a depletion-mode transistor, it is usually necessary to use it with respect to ground to obtain the required leakage current. To provide this capability with a single positive supply, the device includes a low current negative supply generator. This generator uses an internal oscillator and two external capacitors, CNB and CSUB.

Application Information Above is a partial application circuit of the ZNBG series, showing all external components.
Proper biasing is required. The bias circuit is unconditionally stable throughout the process.
The temperature range of the associated FETs and gate and drain capacitances in the circuit. Capacitors CD and CG ensure that residual power and baseboard generator noise are not allowed to affect other external circuits sensitive to RFI. They also suppress any potential RF feedthrough between stages through the ZNBG device. All stages of these uses require capacitors. Values of 10nF and 4.7nF are respectively but it is recommended that this depends on the design, any value between 1nF and 100nF can be used.

Capacitors CNB and CSUB are the components of the ZNBGS negative power generator. This negative bias is generated on-chip using the internal oscillator. The required value capacitors CNB and CSUB are 47nF. This generator produces a low current of about -3 volts. Although this generator is only used to bias external FETs, it can be used to power other external circuits through the CSUB pin.
Resistors RCAL1/2 set the drain current for all external FETs to operate. The two ZNBG devices have devices to program different drain currents into selected FETs. Two RCAL inputs are provided. For the ZNBG4000, resistor RCAL1 sets the leakage current of FETs 1 and 2, and resistor RCAL2 sets the leakage current of FETS 3 and 4. For the ZNBG6000, resistor RCAL1 sets the leakage current in FETs 1 and 4, and resistor RCAL2 sets the leakage current in FETs 2, 3, 5 and 6. If the same leakage current is required for all FETs on either device, pins RCAL1 and RCAL2 can be tied together and grounded through a half-normal value calibration resistor.
If no bias control circuitry is required, its associated drain and gate connections may remain open.
A circuit that does not affect the operation of the rest of the bias circuits. If all FETs are combined with a current setting resistor omitted, the specific RCAL should also be included. Supply current can be reduced using high value RCAL resistors (eg 470K) if needed.

Application Information (continued)
ZNBG devices are designed to protect external FETs from adverse operation.
condition. When the JFET is connected to any bias circuit, the gate output voltage of the bias circuit shall not exceed the range of -3.5 V to 0.7 V under any conditions, including power-up and power-down. transient. Whether the negative bias generator is shorted or overloaded so that the leakage current cannot control the external FET, turn off the FET's drain supply to avoid excessive drain current that can damage the FET.
The figure below shows the ZNBG4000/1 and ZNBG6000/1 in a typical LNB application.
Within each FET gain stage, a numbering system indicates the bias stage and application circuit. This is important when the RCAL value is used to set different drain currents.
Dual Standard or Enhanced LNB Block Diagram