8

SL2017

Required 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 SL2017 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 SL2017 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).

SL2017 Operation

The SL2017 is a downconverter mixer with an AGC

amplifier, which when used with appropriate external varactor

tuned oscillator 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

signal.

The output of the preamplifier is fed to the mixer section

where the RF signal is mixed with the local oscillator

frequency.

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 SL2017 will mix an RF input signal from 950MHz -

2150MHz 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.