Zetex ZNBG3000Q16, ZNBG3001Q16 Datasheet

FET BIAS CONTROLLER

ZNBG3000

ISSUE 1- AUGUST 1998

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 3 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 ZNBG3000/1 contains three 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 ZNBG3000 gives 2.2 volts
drain whilst the ZNBG3001 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.

ZNBG3001

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 ZNBG3000/1 are available in QSOP16
packages for the minimum in devices size.
Device operating temperature is -40 to 70°C
to suit a wide range of environmental
conditions.

FEATURES

Provides bias for GaAs and HEMT FETs

•

Drives up to three 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

•

QSOP surface mount package

•

APPLICATIONS

Satellite receiver LNBs

•

Private mobile radio (PMR)

•

Cellular telephones

•

Single in single out C Band LNB

•

4-137

ZNBG3000
ZNBG3001

ABSOLUTE MAXIMUM RATINGS

Supply Voltage -0.6V to 15V
Supply Current 100mA
Drain Current (per FET) 0 to 15mA

(set by R

CAL1

and R

CAL2

)
Output Current 100mA
Operating Temperature -30 to 70°C
Storage Temperature -40 to 85°C

ELECTRICAL CHARACTERISTICS TEST CONDITIONS (Unless otherwise stated):
T

= = 25°C,VCC=5V,ID=10mA (R

amb

CAL1

Power Dissipation (T

QSOP16 500mW

=33kΩ)Ω)

amb

= = 25°C)

SYMBOL PARAMETER CONDITIONS

V

CC

I

CC

Supply Voltage 5 12 V
Supply Current ID1 to I

D3=0

ID1 to ID3=10mA

V

SUB

Substrate Voltage
(Internally generated)

I
I

SUB
SUB

= 0
= -200µA

Output Noise

E

ND

E

NG

f

O

Drain Voltage
Gate Voltage

Oscillator Freq. 200 330 800 kHz

=4.7nF, CD=10nF

C

G

=4.7nF, CD=10nF

C

G

DRAIN CHARACTERISTICS

I

DO

I

D

∆I
∆I

V

∆∆V
∆∆V

DV

DT

D

Output Current Range Set by R

CAL1

Current 8 10 12 mA
Current Change
with V
with T

CC

j

Voltage ZNBG3000

VCC=5 to 12V 0.5 %/V
Tj=-30 to +70°C 0.05 %/°C
ID1 to ID3=10mA 2

ZNBG3001
Voltage Change

DV

DT

with V
with T

CC

j

VCC= 5 to 12V 0.5 %/V
Tj = -30 to +70°C 50 ppm

LIMITS

UNITS

Min Typ Max

10
40

-3.5 -2.8 -2

-2

0.02

0.005

mA
mA

V
V

Vpkpk
Vpkpk

015mA

1.8

2.2
2

2.4

2.2

V
V

4-138

ZNBG3000
ZNBG3001

SYMBOL PARAMETER CONDITIONS

LIMITS

UNITS

Min Typ Max

GATE CHARACTERISTICS

I

GO

V

OL

V

OH

Notes:

1. The negative bias voltages specified are generated on-chip using an internal oscillator. Two external capacitors, C
47nF are required for this purpose.

2. The characteristics are measured using an external reference resistors R

3. Noise voltage is not measured in production.

4. Noise voltage measurement is made with FETs and gate and drain capacitors in place on all
outputs. C
between drain outputs and ground.

Output Current Range -30 2000

µA

Output Voltage
Output Low ID1 to ID3=12mA

to IG3=0 -3.5 -2 V

IG1

to ID3=12mA

I

D1

I

to IG3= -10µA

G1

-3.5 -2 V

Output High ID1 to ID3= 8mA

to IG3= 0 0.4 1 V

I

G1

and C

NB

of value 33kΩ wired from pin R

CAL1

, 4.7nF, are connected between gate outputs and ground, CD, 10nF, are connected

G

to ground.

CAL1

SUB

, of

4-139