3

SL2035

Electrical Characteristics (continued)

95

25

Characteristic

To device input

To device input

Into 50

Ω load

See Figure 4

Conditions

Max.

Min.

Value

Units

dB

µV

dB

µV

dB

µV

Ω

Ω

Typ.

72

92

75

LO and harmonic leakage

to RF input

Fundamental

2nd harmonic

LO Prescaler output swing

LO Prescaler output impedance

IF output impedance

Pin

7,8

7,8

10

10

1,16

3·3p

6

6

820

PIN 7

PIN 8

2p

325

PIN 1

PIN 16

Figure 3 Approximate model of RF input

Figure 4 Approximate model of IF output

Application Notes

Figure 5 shows the SL2035 in a typical downconverter

application.

The network connected to RF input pin 7 and pin 8 is to

improve the matching between the device input and the

source. The source would normally be from the 1·1MHz

IF output of the upconverter (SL2030) via passive BPF

and gain stage all designed for 50

Ω characteristic

impedance.

The network connected to the IF output pin 1 and pin 16 is

a narrow band tuned balun centred typically on 40MHz.

This matches the device output impedance of nominally

400

Ω (balanced) to 50Ω (unbalanced).

The network connected to the LO pin 12 and pin 13 is a

varactor diode loaded resonant microstrip line resonator.

Fine adjustment of the tuning range can be achieved by

physically moving C19 (see Figure 5) closer to the LO pins.

This extends the bottom end of the tuning range.

It is important to provide good decoupling on the 5V

supplies and to use a layout which provides some isolation

between the RF, IF and LO ports.