SL2015
Required SL2015 VCO
Byte 1
Byte2
Byte 3
Byte 4
Byte 5
Frequency (MHz)
Address
Prog Divider
8 MSB's
Prog Divider
8 LSB's
Prog Divider
/Reference
Divider
Charge Pump
and Port
Control
1500
1600
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
C2
0B
0C
0D
0E
0E
0F
10
11
11
12
XX
XX
B8
80
48
10
D8
A0
68
30
F8
C0
XX
XX
93
93
93
93
93
93
93
93
93
93
93
93
40
40
40
40
40
40
40
40
40
40
11
10
1700
1800
1900
2000
2100
2200
2300
2400
Bottom of Band
Top of Band
Codes above are for Fcomp = 250kHz, prescaler enabled, giving Fstep = 500kHz.
X = Don't care
Table 1. Example I2C Hex codes for SP5659 synthesiser
Switching of SL2015 IF outputs
The output of the preamplifier is fed to the mixer section
where the RF signal is mixed with the local oscillator
frequency, which is generated by an on board oscillator. The
on board oscillator uses an external tuneable sustaining
network and is optimised for low phase noise. This section
also contains a buffer drive whose outputs can be used to
frequency lock the LO carrier to the required channel.
Signals from the mixer are then fed to the AGC IF amplifier,
which gives an overall conversion gain programmable from
-10 to +30 dB. The output of this stage can be switched to one
of two outputs to facilitate IF processing.
Port P0 is used to select the IF ouputs.
When Port P0 is OFF, IF output 1 is selected.
When Port P0 is ON, IF output 2 is selected.
Switching of SL2015 AGC
Port P1 is used to program the AGC gain.
When Port P1 is OFF, AGC is set to 4V (minimum gain).
When Port P1 is ON, the AGC is set to 1V (maximum gain).
The SL2015 will mix an RF input signal from 950MHz -
2150MHzwithitsownlocaloscillator,andproduceanIFsignal
typically at 402.75MHz or 479.5MHz.
The device has a number of features, which may be either
programmable via a synthesiser and operated as part of a
dynamic AGC loop, or hardwired into a fixed mode.
There are a variety of parameters which can be measured
using this evaluation board.
SL2015 Operation
The SL2015 is a downconverter mixer oscillator with an
AGC amplifier, which when used with appropriate external
varactor tuned oscillator sustaining network performs the first
IF tuning function for a full band satellite receiver system.
In application the RF input of the device is interfaced
through appropriate impedance matching to the first IF signal,
which is down linked from the outdoor unit at typically 950-
2150MHz. The RF input preamplifier of the device is designed
for low noise figure and for low distortion so eliminating the
requirement for RF AGC. The preamplifier also provides gain
to the mixer section and back isolation from the local oscillator
section.
Use with external oscillator.
For applications that require extremely good phase noise,
typically >-75dBc @ 10kHz across the band, it is
recommended that the SL2017 together with an external local
oscillator is used.
The SL2017 is functionally equivalent to the SL2015,
however the tank inputs have been modified to act as a buffer
to an external VCO. Further details of this application are
shown in the SL2017 Datasheet.
8
MITEL [ MITEL NETWORKS CORPORATION ]
