FET BIAS CONTROLLER WITH POLARISATION
SWITCH AND TONE DETECTION
ISSUE 2 - APRIL 1998
ZNBG3110
ZNBG3111
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 three 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 ZNBG3110/11 includes bias circuits to
drive up to three external FETs. A control
input to the device selects either one of two
FETs as operational, the third FET is
permanently active. This feature is
particularly used as an LNB polarisation
switch. Also specific to LNB applications is
the 22KHz tone detection and logic output
feature which is used to enable high and low
band frequency switching.
Drain current setting of the ZNBG3110/11 is
user selectable over the range 0 to 15mA, this
is achieved with addition of a single resistor.
The series also offers the choice of drain
voltage to be set for the FETs, the 3110 gives
2.2 volts drain whilst the 3111 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.
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 1V. 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 ZNBG3110/11 are available in QSOP20
for the minimum in device 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
•
Polarisation switch for LNBs
•
22KHz tone detection for band
•
switching
Compliant with ASTRA control
•
specifications
QSOP surface mount package
•
APPLICATIONS
Satellite receiver LNBs
•
Private mobile radio (PMR)
•
Cellular telephones
•
4-123
ZNBG3110
ZNBG3111
ABSOLUTE MAXIMUM RATINGS
Supply Voltage -0.6V to 12V
Supply Current 100mA
Input Voltage (V
Drain Current (per FET) 0 to 15mA
(set by R
CAL
Operating Temperature -40 to 70°C
Storage Temperature -50 to 85°C
) 25V Continuous
POL
)
Power Dissipation (T
amb
= = 25°C)
QSOP20 500mW
ELECTRICAL CHARACTERISTICS. TEST CONDITIONS
(Unless otherwise stated):T
SYMBOL PARAMETER CONDITIONS
V
CC
I
CC
V
SUB
E
ND
E
NG
f
O
Supply Voltage 5 10 V
Supply Current ID1 to ID3=0
I
I
I
I
Substrate
(Internally generated) I
Voltage
Output Noise
Drain Voltage
Gate Voltage
C
C
Oscillator
Frequency
= = 25°C,VCC=5V,ID=10mA (R
amb
=0,ID2 to ID3=10mA, V
D1
=0,ID1 to ID3=10mA, V
D2
=0, ILB=10mA
D1 to ID3
=0, IHB=10mA
D1 to ID3
I
=4.7nF, CD=10nF
G
=4.7nF, CD=10nF
G
POL
POL
SUB
SUB
=14V
=15.5V
=0
=-200µA
=33kΩΩ)
CAL
LIMITS
UNITS
MIN. TYP. MAX.
15
mA
35
mA
35
mA
45
mA
45
mA
-3.5 -3.0 -2.5
-2.4VV
0.02
Vpkpk
0.005
Vpkpk
200 350 800 kHz
4-124
ZNBG3110
ZNBG3111
SYMBOL PARAMETER CONDITIONS
GATE CHARACTERISTICS
I
GO
V
G1O
V
G1L
V
G1H
V
G2O
V
G2L
V
G2H
V
G3L
V
G3H
Output Current
Range
Output Voltage
Gate 1 Off
Low
High
Output Voltage
Gate 2 Off
Low
High
Output Voltage
Gate 3 Low
High
V
I
Dx
POL
(mA) (V) (µµA)
=0 V
I
D1
I
D1
I
D1
I
D2
I
D2
I
D2
I
D3
I
D3
POL
=12 V
POL
=8 V
POL
=0 V
POL
=12 V
POL
=8 V
POL
=12 I
=8 I
DRAIN CHARACTERISTICS
I
DI
DI
V
V
V
DV
DV
I
I
D
DV
DT
D1
D2
D3
DV
DT
L1
L2
Current 8 10 12 mA
Current Change
with V
with T
VCC= 5 to 10V
CC
T
j
j
=-40 to +70°C
Drain 1 Voltage:
High
ZNBG3110
ZNBG3111
=10mA, V
I
D1
I
=10mA, V
D1
Drain 2 Voltage:
High
ZNBG3110
ZNBG3111
=10mA, V
I
D2
=10mA, V
I
D2
Drain 3 Voltage:
High
ZNBG3110
ZNBG3111
=10mA, V
I
D3
=10mA, V
I
D3
Voltage Change
with V
with T
VCC= 5 to 10V
CC
T
j
j
=-40 to +70°C
Leakage Current
Drain 1
Drain 2
V
D1
V
D2
=0.1V, V
=0.1V, V
=14 I
=15.5 I
=15.5 I
=15.5 I
=14 I
=14 I
=15.5V
POL
=15.5V
POL
=14V
POL
=14V
POL
=15.5V
POL
=15.5V
POL
=14V
POL
=15.5V
POL
I
GOx
GO1
GO1
GO1
GO2
GO2
GO2
GO3
GO3
=-10
=-10
=0
=-10
=-10
=0
=-10
=0
LIMITS
MIN. TYP. MAX.
-30 2000
-2.7
-2.4
-2.0
-2.7
-2.4
-2.0
0.4
0.75
1.0
-2.7
-2.4
-2.0
-2.7
-2.4
-2.0
0.4
0.75
1.0
-3.5
-2.9
-2.0
0.4
0.75
1.0VV
0.2
0.05
2.0
2.2
2.4
1.8
2.0
2.2VV
2.0
2.2
2.4
1.8
2.0
2.2VV
2.0
2.2
2.4
1.8
2.0
2.2VV
0.5
50
10
10
UNITS
µA
V
V
V
V
V
V
%/V
%/°C
%/V
ppm
µA
µA
4-125
ZNBG3110
ZNBG3111
SYMBOL PARAMETER CONDITIONS
LIMITS
MIN. TYP. MAX.
TONE DETECTION CHARACTERISTICS
Filter Amplifier
I
B
V
I
OUT
G
OUT
V
Input Bias Current
Output Voltage
Output Current 5V
=150kΩ
R
F1
5
RF1=150kΩ
OUT
=1.96V, V
=2.1V 400 520 650
FIN
Voltage Gain f=22kHz,VIN=1mV 46 dB
0.04 0.15 1.0
1.75 1.95 2.05 V
Comparator
V
TH
Threshold
Voltage
5
f=0 2.95 3.2 3.45 V
Output Stage
V
I
V
V
V
V
LOV
LOV
LBL
LBH
HBL
HBH
Volt. Range IL=50mA(LB or HB)-0.5V
L
OV
LOV Bias Current V
LB Output Low
LB Output High V
HB Output Low
HB Output High V
=0 0.04 0.15 1.0
LOV
=0 IL=-10µA Enabled
V
LOV
V
=3V IL=0 Enabled
LOV
=0 IL=10mA Disabled
LOV
V
=3V IL=50mA Disabled
LOV
=0 IL=-10µA Enabled
V
LOV
V
=3V IL=0 Enabled
LOV
=0 IL=10mA Disabled
LOV
V
=3V IL=50mA Disabled
LOV
6
7
6
7
6
7
6
7
-3.5
-0.01
-0.025
2.903.0
-3.5
-0.01
-0.025
2.903.0
-2.750-2.5
-2.750-2.5
CC
0.01VV
0.025
3.1VV
0.01VV
0.025
3.1VV
POLARITY SWITCH CHARACTERISTICS
I
POL
V
TPOL
T
SPOL
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 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 o utputs. C
gate outputs and ground, C
5 . These parameters are lneearly related to V
6. These parameters are measured using Test Circuit 1
7. These parameters are measured using Test Circuit 2
Input Current
Threshold
Voltage
Switching Speed
, 10nF, are connected between drain outputs and ground.
D
=25V (Applied via R
V
POL
=25V (Applied via R
V
POL
=25V (Applied via R
V
POL
CC
=10kΩ)
POL
=10kΩ)
POL
=10kΩ)
POL
of value 33k wired from pins R
CAL
10 20 40
14 14.75 15.5 V
100 ms
to ground.
CAL
, 4.7nF, are connected between
G
-1.8 V
and C
NB
UNITS
µA
µA
µA
µA
SUB
, of
4-126
TEST CIRCUIT 1
TEST CIRCUIT 2
ZNBG3110
ZNBG3111
V2 Characteristics
Type AC source
Frequency 22kHz
Voltage 350mV p/p enabled
100mV p/p disabled
V2 Characteristics
Type AC source
Frequency 22kHz
Voltage 350mV p/p enabled
100mV p/p disabled
4-127