Diodes ZNBG6001 User Manual

FET BIAS CONTROLLER

ISSUE 2 - JUNE 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
resistors the devices provide drain voltage
and current control for a number of 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 ZNBG4000/1 and ZNBG6000/1 contain
four and six bias stages respectively. In
setting drain current the ZNBG4000/1 two
resistors allows individual FET pair control
to different levels, the ZNBG6000/1 two
resistors split control between two and four
FETs. This allows the operating current of
input FETs to be adjusted to minimise noise,
whilst the following FET stages can
separately be adjusted for maximum gain.
The series also offers the choice of drain
voltage to be set for the FETs, the
ZNBG4000/6000 gives 2.2 volts drain whilst
the ZNBG4001/6001 gives 2 volts.

ZNBG4000ZNBG4000 ZNBG4001
ZNBG6000 ZNBG6001

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.

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 ZNBG4000/1 and ZNBG6000/1 are
available in QSOP16 and 20 pin packages
respectively 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 four or six 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

•

4-137

ZNBG4000ZNBG4000 ZNBG4001
ZNBG6000 ZNBG6001

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 -40 to 70°C
Storage Temperature -50 to 85°C

Power Dissipation (T

amb

= = 25°C)

QSOP16 500mW
QSOP20 650mW

ELECTRICAL CHARACTERISTICS TEST CONDITIONS (Unless otherwise stated):
T

= = 25°C,VCC=5V,ID=10mA (R

amb

SYMBOL PARAMETER CONDITIONS

CAL1

=33kΩ;R

CAL2

=33kΩΩ)

LIMITS

UNITS

Min Typ Max

V

CC

I

CC

I

CC

V

SUB

Supply Voltage 5 12 V
Supply Current

ZNBG4000/1
Supply Current

ZNBG6000/1
Substrate Voltage

(Internally generated)

ID1 to ID4=0

to ID4=10mA

I

D1

ID1 to ID6=0

to ID6=10mA

I

D1

I

= 0

SUB

I

= -200µA

SUB

-3.5 -3 -2

10
50

15
75

-2

mA
mA

mA
mA

V
V

Output Noise

E

ND

E

NG

f

O

Drain Voltage
Gate Voltage

Oscillator Freq. 200 350 800 kHz

=4.7nF, CD=10nF

C

G

=4.7nF, CD=10nF

C

G

0.02

0.005

Vpkpk
Vpkpk

DRAIN CHARACTERISTICS

I

D

∆I
∆I

V

∆∆V
∆∆V

DV

DT

D

Current 8 10 12 mA
Current Change
with V
with T

CC

j

VCC=5 to 12V 0.02 %/V
Tj=-40 to +70°C 0.05 %/°C

Voltage
ZNBG4000, ZNGB6000
ZNBG4001, ZNBG6001

2

1.8

2.2
2

Voltage Change

DV

DT

with V
with T

CC

j

VCC= 5 to 12V 0.5 %/V
Tj = -40 to +70°C 50 ppm

2.4

2.2

V
V

4-138

ZNBG4000ZNBG4000 ZNBG4001
ZNBG6000 ZNBG6001

SYMBOL PARAMETER CONDITIONS

LIMITS

UNITS

Min Typ Max

GATE CHARACTERISTICS

I

GO

V

OL

V

OH

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 two external reference resistors R
ground. For the ZNBG4000, resistor R
For the ZNBG6000, resistor 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
ZNBG4000/1

Output Low ID1 to ID4=12mA

to IG4=0 -3.5 -2 V

I

G1

to ID4=12mA

I

D1

to IG4= -10µA

I

G1

-3.5 -2 V

Output High ID1 to ID4= 8mA

to IG4= 0 0 1 V

I

G1

Output Voltage
ZNBG6000/1

Output Low ID1 to ID6=12mA

I

to IG6= 0 -3.5 -2 V

G1

to ID6=12mA

I

D1

I

to IG6= -10µA

G1

-3.5 -2 V

Output High ID1 to ID6= 8mA

to IG6= 0 0 1 V

I

G1

and C

NB

and R

sets the drain current of FETs 1 and 2, resistor R

CAL1

sets the drain current of FETs 1 and 4, resistor R

CAL1

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

G

CAL1

of value 33kΩ wired from pins R

CAL2

sets the drain current of FETs 3 and 4.

CAL2

sets the drain current of FETs 2, 3, 5 and 6.

CAL2

CAL1/2

SUB

, of

to

4-139