ADL5592

Rev. 0 | Page 14 of

20

GSM/EDGE TRANSMIT APPLICATION

Figure 20, Figure 21, and Figure 22 show effects of different input

power levels on the spectral mask and EVM. The gain code is held

constant at the minimum attenuation (corresponding to Code 0

for both attenuators).

At low output power levels, both the spectral mask and EVM

remain flat. At higher output power levels, however, the spectral

mask expands and the EVM increases.

At an output of 12 dBm at 925.5 MHz, the peak and rms EVM

are 0.56% and 1.51%, respectively. The spectral mask offsets at

400 kHz, 600 kHz, and 1.2 MHz sit at −72.2 dBc, −84.8 dBc,

and −88.01 dBc, respectively.

Note that the minimum attenuation setting results in the highest

spectral mask and EVM values (excluding noise floor limitations).

Increasing the input attenuation of ATTN 1 causes less power to

be presented to the amplifier stage. Therefore, the levels of the

spectral mask and EVM decrease as the input attenuation of

ATTN 1 is increased. As the output attenuation of ATTN 2 is

increased, the levels of the spectral mask and EVM remain flat.

SOLDERING INFORMATION

On the underside of the chip scale package, there is an exposed

compressed paddle. This paddle is internally connected to the

chip’s ground. Solder the paddle to the low impedance ground

plane on the printed circuit board to ensure specified electrical

performance and to provide thermal relief. It is also recommended

that the ground planes on all layers under the paddle be stitched

together with vias to reduce thermal impedance.

0

–10

–20

–30

–40

–50

–60

–70

–80

–90

–100

10

9

8

7

6

5

4

3

2

1

0

7.5

10.0

12.5

15.0

17.5

OUTPUT (dBm)

400kHz OFFSET

RMS EVM

PEAK EVM

600kHz OFFSET

1.2MHz OFFSET

Figure 20. EVM and Spectral Mask vs. Output Power,

488.8 MHz EDGE Signal, 270 nH RF Choke, Minimum Attenuation

0

–10

–20

–30

–40

–50

–60

–70

–80

–90

–100

10

9

8

7

6

5

4

3

2

1

0

7.5

10.0

12.5

15.0

17.5

OUTPUT (dBm)

400kHz OFFSET

RMS EVM

PEAK EVM

600kHz OFFSET

1.2MHz OFFSET

Figure 21. EVM and Spectral Mask vs. Output Power,

925.5 MHz EDGE Signal, 270 nH RF Choke, Minimum Attenuation

0

–10

–20

–30

–40

–50

–60

–70

–80

–90

–100

10

9

8

7

6

5

4

3

2

1

0

7.5

10.0

12.5

15.0

17.5

OUTPUT (dBm)

400kHz OFFSET

RMS EVM

PEAK EVM

600kHz OFFSET

1.2MHz OFFSET

Figure 22. EVM and Spectral Mask vs. Output Power,

1960 MHz EDGE Signal, 33 nH RF Choke, Minimum Attenuation