znbg3113 Zetex Semiconductors plc., znbg3113 Datasheet - Page 12

• Manufacturer Part Number: znbg3113
• Description: Znbg3113 - Fet Bias Controller With Polarization Switch And Tone Detection
• Manufacturer: Zetex Semiconductors plc.

APPLICATIONS INFORMATION(cont)
The following block diagram shows the main section of an LNB designed for use with the Astra
series of satellites. The ZNBG3113/14 is the core bias and control element of this circuit. The
ZNBG provides the negative rail, FET bias control, polarisation switch control, tone detection and
band switching with the minimum of external components. Compared to other discrete
component solutions the ZNBG circuit reduces component count and overall size required.
Tone detection and band switching is provided on the ZNBG3113/14 devices. The following
diagrams describes how this feature operates in an LNB and the external components required.
The presence or absence of a 22kHz tone applied to pin F
H
to be compatible with both MMIC and discrete local oscillator applications, selected by pin L
Referring to Figure 1 wiring pin L
(disabled) and 0V (enabled). Referring to Figure 2 wiring pin L
a potential divider across V
force the L
Tone Detection Function
Note 1: 0 volts in typical LNB applications but ependent on extenal circuits.
Single Universal LNB Block Diagram
L
G
V
B
OV
. A tone present enables H
OSC
ZNBG3113
ZNBG3114
ND
B
and H
F
22kHz
—
22kHz
—
B
IN
outputs to provide the required oscillator supply, V
CC
B
and ground set to the required oscillator supply voltage, V
and tone absent enables L
L
Disabled
Enabled
Disabled
Enabled
B
OV
to ground will force L
4-134
H
Enabled
Disabled
Enabled
Disabled
B
B
IN
. The L
enables one of two outputs, L
B
OV
and H
to a positive voltage source (e.g.
L
-2.6 volts
G
Note 1
V
B
B
OSC
ND
and H
B
to switch between -2.6V
OSC
B
outputs are designed
, when enabled.
H
G
-2.6 volts
V
Note 1
OSC
B
ND
OSC
B
) will
and
OV
.