SL1925 Ver la hoja de datos (PDF) - Mitel Networks
Número de pieza
componentes Descripción
Fabricante
SL1925 Datasheet PDF : 20 Pages
| |||
Preliminary Information
SL1925
SL1925 Demo Board
The demo board contains an SL1925 direct conversion
IC and SP5769 synthesiser. Reference to the
specifications for each device may be required in
conjunction with these notes.
The board contains all components necessary to
demonstrate operation of the SL1925. The schematic
and PCB layout of the board are shown in figures 16, 17
and 18. The SP5769 synthesiser is provided to control
each of the oscillators of the SL1925.
Supplies
The board must be provided with the following supplies:
5V for the synthesiser, 30V for the varactor line and 5V
for the SL1925.
The supply connector is a 5 pin 0.1” pitch pin header.
The order of connections is 5V - GND - 30V - GND - 5V
I2C Bus Connections
The board is provided with a RJ11 I2C bus connector
which feeds directly to the SP5769 synthesiser. This
connects to a standard 4 way cable which is supplied
with the interface box.
Operating Instructions
1. Software
Use the Mitel Semiconductor synthesiser software. Pull
down the I2C bus section menu then select the SP5769.
It is suggested that the charge pump setting 130uA is
used, and the reference divider is set to 32. These
settings give a small loop bandwidth (i.e. 100’s Hz),
which allows detailed phase noise measurements of the
oscillators to be taken, if desired.
2. VCO control
The two VCO’s are selected by toggling port P1 on the
synthesiser which in turn toggles the LOsel input of the
SL1925.
VCOS is switched on (and hence VCOV off) by clicking
P1 on - a tick will appear.
VCOS oscillates at twice the LO frequency (lower band)
and is then divided by two to provide the required LO
frequency in the range 950MHz to 1500MHz
approximately.
VCOV is switched on (and hence VCOS off) by clicking
P1 off - no tick.
VCOV oscillates at the LO frequency (upper band) in the
range 1450MHz to 2150MHz approximatley.
3. AGC control
The AGC input of the SL1925 which determines the
conversion gain should be controlled by application of an
external voltage to the AGC pin, TP1.
Caution: Care should be taken to ensure the chip is
powered ON when +ve voltages are applied to the AGC
input so as to avoid powering the chip up via the ESD
protection diode of the AGC input. It is recommended
that a low current limit is set on the external source used.
4. Free running the VCO’s
Select the required VCO using port P1 and then using
the software choose an LO frequency which is above the
maximum frequency capability of the oscillator. 3GHz
is suggested for both oscillators. Under this condition the
varactor control voltage is pumped to its maximum
value, i.e. to the top of the band. The oscillator frequency
may be manually tuned by varying the 30V supply.
15
Share Link: 