Data Sheet

ADL5903

Rev. B | Page 17 of 20

Modulation/Standard

Peak Envelope

Power Ratio (dB)

Carrier

Bandwidth (MHz)

Output Noise

(mV p-p)

Rise/Fall

Times (μs)

QPSK, 5 MSPS (SQR COS Filter,

 = 0.35)

4.0

5

10

140

3.5/32

QPSK ,15 MSPS (SQR COS Filter,

 = 0.35)

4.1

15

10

80

3.5/32

64 QAM, 1 MSPS (SQR COS Filter,

 = 0.35)

7.4

1

1000

60

280/2600

64 QAM, 5 MSPS (SQR COS Filter,

 = 0.35)

7.4

5

100

50

34/330

64 QAM, 13 MSPS (SQR COS Filter,

 = 0.35)

7.4

13

100

50

34/330

W-CDMA, One-Carrier, TM1-64

10.56

3.84

100

80

34/330

W-CDMA Four-Carrier, TM1-64, TM1-32, TM1-16, TM1-8

12.08

18.84

100

96

34/330

LTE, TM1, One-Carrier, 20 MHz (2048 QPSK Subcarriers)

11.58

20

100

76

34/330

popular modulation schemes. The output response time and

noise performance are also shown. Using lower capacitor values

results in faster response times but can result in degraded rms

measurement accuracy. If the output noise shown in Table 4 is

implementing an averaging algorithm after the output voltage of

the ADL5903 has been sampled by an analog-to-digital

converter (ADC).

The values in Table 4 were experimentally determined to be the

minimum capacitance that ensures good rms accuracy for that

particular signal type. This test was initially performed with a

large capacitance value on the CRMS pin (for example, 10 μF).

can be accomplished with press-down capacitors) until the

indicates that the accuracy of the rms computation is degrading

also tends to increase as the bandwidth of the carrier decreases.

output tends to have a correspondingly narrow profile. The

that reduces the low-pass corner frequency of the averaging

function and ensures a valid rms computation.

DEVICE CALIBRATION AND ERROR CALCULATION

The measured transfer function of the ADL5903 at 2.14 GHz is

shown in Figure 45, which contains plots of both output voltage

and log conformance error vs. input level for one device. As the

input level varies from −30 dBm to +14 dBm, the output voltage

varies from near 0 V to 1.9 V.

+85°C, and +125°C

Board level calibration must be performed to achieve high

accuracy because the slope and intercept vary from device to

device. For a two-point calibration, write the equation for the

idealized output voltage as

(1)

where:

Slope is the change in output voltage divided by the change in

input level (dBm).

Intercept is the calculated input level at which the output voltage

is equal to 0 V (note that Intercept is an extrapolated theoretical

value and not a measured value).

In general, calibration is performed during equipment

manufacture by applying two or more known signal levels to the

input of the ADL5903 and measuring the corresponding output

voltages. The calibration points must be within the linear

operating range of the device.

With a two-point calibration, calculate the slope and intercept

as follows:

(2)

(3)

20

15

10

5

0

–5

–10

–15

–20

–25

–30

–35

–40

2.4

2.2

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

6

5

4

3

2

1

0

–1

–2

–3

–4

–5

–6

–55°C

–40°C

+25°C

+85°C

+125°C

CALIBRATION AT –10dBm AND +10dBm