ADL5501AKSZ-R71 datasheet(20/28 Pages) AD

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ADL5501

Rev. B | Page 20 of 2

Table 4. Waveform and Output Filter Effects on Residual AC

Output

Residual AC

Waveform

CFILT, COUT

V dc

mV p-p

mV rms

64QAM

1 nF,

0.5

(7.4 dB CF)

open

1.0

175

2.0

394

Open,

0.5

5.5

0.1 μF

1.0

2.0

212

1 nF,

0.5

5.5

0.1 μF

1.0

2.0

200

W-CDMA RL

1 nF,

0.5

6.4

0.8

(3.4 dB CF)

open

1.0

2.6

2.0

6.6

Open,

0.5

4.5

0.6

0.1 μF

1.0

2.2

2.0

4.9

1 nF,

0.5

3.1

0.5

0.1 μF

1.0

9.6

1.4

2.0

3.9

CDMA2000 DL

1 nF,

0.5

8.6

(6.7 dB CF)

open

1.0

148

2.0

339

Open,

0.5

3.9

0.1 μF

1.0

7.9

2.0

119

1 nF,

0.5

3.7

0.1 μF

1.0

7.7

2.0

116

W-CDMA UL

1 nF,

0.5

204

TM1-64, 1 CR

open

1.0

396

2.0

840

140

Open,

0.5

0.1 μF

1.0

112

2.0

227

1 nF,

0.5

0.1 μF

1.0

114

2.0

243

POWER CONSUMPTION, ENABLE, AND POWER-

ON/POWER-OFF RESPONSE TIME

The quiescent current consumption of the ADL5501 varies with

the size of the input signal from approximately 1.1 mA for no

signal up to 6.2 mA at an input level of 0.7 V rms (10 dBm,

re: 50 Ω). If the input is driven beyond this point, the supply

current increases sharply (as shown in Figure 6). There is little

variation in quiescent current with power supply voltage.

The ADL5501 can be disabled either by pulling ENBL (Pin 5) to

COMM (Pin 4) or by removing the supply power to the device.

Disabling the device via the ENBL function reduces the leakage

current to less than 1 μA.

If the input of the ADL5501 is driven while the device is disabled

(ENBL = COMM), the leakage current of less than 1 μA increases

as a function of input level. When the device is disabled, the

output impedance increases to approximately 33.5 kΩ.

The turn-on time and pulse response is strongly influenced by

the size of the square-domain filter and output shunt capacitor.

Figure 45 shows a plot of the output response to an RF pulse on

the RFIN pin, with a 0.1 μF output filter capacitor and no

square-domain filter capacitor. The falling edge is particularly

dependent on the output shunt capacitance, as shown in Figure 45.

2ms/DIV

400mV rms RF INPUT

250mV rms

160mV rms

70mV rms

PULSED RFIN

Figure 45. Output Response to Various RF Input Pulse Levels,

Supply = 3 V, Frequency = 900 MHz,

Square-Domain Filter Open, Output Filter = 0.1 μF

To improve the falling edge of the enable and pulse responses,

a resistor can be placed in parallel with the output shunt capacitor.

The added resistance helps to discharge the output filter capacitor.

Although this method reduces the power-off time, the added

load resistor also attenuates the output (see the Output Drive

Capability and Buffering section).

2ms/DIV

400mV rms RF INPUT

250mV rms

160mV rms

70mV rms

PULSED RFIN

Figure 46. Output Response to Various RF Input Pulse Levels,

Supply = 3 V, Frequency = 900 MHz,

Square-Domain Filter Open, Output Filter = 0.1 μF with Parallel 1 kΩ

The square-domain filter improves the rms accuracy for high

crest factors (see the Selecting the Square-Domain Filter and

Output Low-Pass Filter section), but it can hinder the response

time. For optimum response time and low ac residual, both the

square-domain filter and the output filter should be used.

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