znbg2001 Zetex Semiconductors plc., znbg2001 Datasheet

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znbg2001

Manufacturer Part Number
znbg2001
Description
Fet Bias Controller
Manufacturer
Zetex Semiconductors plc.
Datasheet
FET BIAS CONTROLLER
DEVICE DESCRIPTION
The ZNBG series of devices are 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
2 external grounded source FETs, generating the
regulated negative rail required for FET gate biasing
whilst operating from a single supply. This negative
bias, at -3 volts, can also be used to supply other
external circuits.
The ZNBG2000/1 contains two bias stages. A single
resistor allows FET drain current to be set to the
desired level. The series also offers the choice of
drain voltage to be set for the FETs, the ZNBG2000
gives 2.2 volts drain whilst the ZNBG2001 gives 2
volts.
These devices are unconditionally stable over the full
working temperature with the FETs in place, subject
to the inclusion of the recommended gate and drain
capacitors. These ensure RF stability and minimal
injected noise.
FEATURES
ISSUE 1 - AUGUST 2001
Provides bias for GaAs and HEMT FETs
Drives up to two FETs
Dynamic FET protection
Drain current set by external resistor
Regulated negative rail generator requires only 2
external capacitors
Choice in drain voltage
Wide supply voltage range
MSOP surface mount package
1
It is possible to use less than the devices full
complement of FET bias controls, unused drain and
gate connections can be left open circuit without
affecting operation of the remaining bias circuits.
In order to protect the external FETs the circuits have
been designed to ensure that, under any conditions
including power up/down transients, the gate drive
from the bias circuits cannot exceed the range -3.5V
to 0.7V. Furthermore if the negative rail experiences a
fault condition, such as overload or short circuit, the
drain supply to the FETs will shut down avoiding
excessive current flow.
The ZNBG2000/1 are available in MSOP10 packages
for the minimum in devices size. Device operating
temperature is -40 to 80°C to suit a wide range of
environmental conditions.
APPLICATIONS
Satellite receiver LNBs
Private mobile radio (PMR)
Single in single out C Band LNB
Cellular telephones
ZNBG2000
ZNBG2001

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znbg2001 Summary of contents

Page 1

... FET drain current to be set to the desired level. The series also offers the choice of drain voltage to be set for the FETs, the ZNBG2000 gives 2.2 volts drain whilst the ZNBG2001 gives 2 volts. These devices are unconditionally stable over the full ...

Page 2

... Oscillator Freq. O DRAIN CHARACTERISTICS I Output Current Range DO I Current D Current Change with with Voltage ZNBG2000 D ZNBG2001 Voltage Change with with GATE CHARACTERISTICS I Output Current Range GO Output Voltage V Output Low OL V Output High OH Notes: 1 ...

Page 3

... ISSUE 1 - AUGUST 2001 Note:- Operation with loads > 200µA Vcc = 5V 0.0 -0.5 -1.0 Vcc = 5V -1.5 -2.0 -2.5 -3 0.2 External Vsub Load (mA) Vsub v External Load 2.2 ZNBG2000 2.1 2.0 Vcc = 10V 1.9 1 Drain Current (mA) JFET Drain Voltage v Drain Current 5 3 ZNBG2000 ZNBG2001 is not guaranteed 10V 0.4 0.6 0.8 1.0 ZNBG2001 ...

Page 4

... V Set reference, for the D ZNBG2000 this is nominally 2.2 volts whilst the ZNBG2001 provides nominally 2 volts. The drain current taken by the FET is monitored by the low value resistor I the gate of the FET adjusts the gate voltage of Q that the drain current taken matches the current ...

Page 5

... FETs can no longer be controlled, the drain supply to FETs is shut down to avoid damage to the FETs by excessive drain current. and NB The following diagram show the ZNBG2000/1 in typical LNB applications ZNBG2000 ZNBG2001 APPLICATIONS 16k ...

Page 6

... ZNBG2001 INFORMATION CONT. ZNBG2000 GND CNB1 CNB2 ORDERING INFORMATION Part Number ZNBG2000X10 ZNBG2001X10 ZNBG2000/01 Pinout For MSOP10 Package Designator - X 1 VCC D2 G2 RCAL CSUB Package Part Mark QTY Reel MSOP10 ZNBG2000 4000 MSOP10 ZNBG2001 4000 9 6 APPLICATIONS ISSUE 1 - AUGUST 2001 ...

Page 7

... The Company reserves the right to alter without notice the specification, design, price or conditions of supply of any product or service. www.zetex.com For the latest product information, log on to ISSUE 1 - AUGUST 2001 ZNBG2000 ZNBG2001 a DIM Millimetres tol ...

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