Matched Broadband RF VGA

400MHz to 2700MHz

Glitch-Free

18

Rev 3, April 2015

IDTF0480NBGI

Datasheet

The IDTF0480 EVkit is unconditionally stable as shown on page 14, bottom right graph.

One can ensure that the device itself is unconditionally stable (Rollett Stability factor [K] > 1) regardless of trace and

connector losses present in the actual application by adding a shunt 500 ohm resistor at the output. For the HB

configuration , it is also advised to change R8 to 400K and C5 to 4.7 pF.

This 500 ohm shunt load will reduce the gain by about 0.4 dB but leave the rest of the performance parameters such

as IP3, S22, etc. virtually unchanged.

The 500 ohm shunt load will ensure that the device is unconditionally stable WITHOUT the presence of the input and

output traces and connectors associated with the EVkit. In all cases we do recommend that the output capacitor, C5,

be placed as close to the output of the package as possible.

Gain Comparison (25C Ambient) and Output IP3 Comparison (2.7 GHz Frequency)

Shunt 500 ohm output resistor with

100 pF DC block to ground.

Alternately can be hooked directly to

V

Change C5 to 4.7 pF

(HB config only)

Change R8 to 400K

(HB config only)

7

8

9

10

11

12

13

14

15

0.7

0.9

1.1

1.3

1.5

1.7

1.9

2.1

2.3

2.5

2.7

No Load

Shunt 500 ohm Load

Frequency (GHz)

5

10

15

20

25

30

35

40

45

50

-5

-4

-3

-2

-1

0

1

2

3

4

5

6

No Load 25C

Shunt Load 25C

No Load -40C

Shunt Load -40C

No Load 105C

Shunt Load 105C

Output Power / Tone (dBm)

Output Power / Tone (dBm)

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

No Load

Shunt 500 ohm Load

Frequency (GHz)