8

SL2015

Required SL2015 VCO

Byte 1

Byte2

Byte 3

Byte 4

Byte 5

Frequency (MHz)

Address

Prog Divider

Prog Divider

Prog Divider

Charge Pump

8 MSB's

8 LSB's

/Reference

and Port

Divider

Control

1500

C2

0B

B8

93

40

1600

C2

0C

80

93

40

1700

C2

0D

48

93

40

1800

C2

0E

10

93

40

1900

C2

0E

D8

93

40

2000

C2

0F

A0

93

40

2100

C2

10

68

93

40

2200

C2

11

30

93

40

2300

C2

11

F8

93

40

2400

C2

12

C0

93

40

Bottom of Band

C2

XX

XX

93

11

Top of Band

C2

XX

XX

93

10

Codes above are for Fcomp = 250kHz, prescaler enabled, giving Fstep = 500kHz.

X = Don't care

Switching of SL2015 IF outputs

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).

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.

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.

The SL2015 will mix an RF input signal from 950MHz -

2150MHz with its own local oscillator, and produce an IF signal

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.

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.