Product Specification

SP4257

Page 4 of 6

Evaluation Kit

The SPDT Switch Evaluation Kit board was designed to

ease customer evaluation of the SP4257 SPDT switch.

The RF common port is connected through a 50

Ω

transmission line to J2. Port 1 and Port 2 are

connected through 50

Ω transmission lines to J1 and

J3. A through transmission line connects SMA

connectors J4 and J5. This transmission line can be

used to estimate the loss of the PCB over the

environmental conditions being evaluated.

The board is constructed of a four metal layer FR4

material with a total thickness of 0.031”. The

transmission lines were designed using a coplanar

waveguide with ground plane (28 mil core, 47.6 mil

width, 30mil gap).

Note the number of vias surrounding the device in the

layout shown in Figure 8. These vias are critical for

obtaining the specified isolation performance for the

device shown in this datasheet.

J6 provides a means for controlling DC and digital

inputs to the device. The provided jumpers short the

package pin to ground for logic low. When the jumper

is removed, the pin is pulled up to VDD for logic high.

When the jumper is in place, 3 µA of current will flow

through the 1 M

Ω pull up resistor. This extra current

should not be attributed to the requirements of the

device.

Figure 8. Evaluation Board Layouts

Figure 9. Evaluation Board Schematic

50 OHM T-Line

50 OHM T-Line

50 OHM T-Line

50 OHM T-Line

1

J5

J5

R1

1M

R1

1M

1

1

3

3

5

5

7

7

2

2

4

4

6

6

8

8

10

10

12

12

14

14

13

13

9

9

11

11

J6

HEADER 7X2

J6

HEADER 7X2

R2

1M

R2

1M

1

J4

J4

1

J3

J3

GND

2

RF1

3

GND

4

GND

5

GND

1

GND

12

GND

11

RF2

13

GND

14

GND

15

U1

PE4255/PE4257/PE42551

U1

PE4255/PE4257/PE42551

C3

DNI

C3

DNI

C2

DNI

C2

DNI

C1

DNI

C1

DNI

1

J2

J2

1

J1

J1

Tel: +86-23-62808818

Fax: +86-23-62805284

www.sipatsaw.com / sawmkt@sipat.com