AD8361ARM datasheet(17/24 Pages) AD

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AD8361

Rev. C | Page 17 of 24

The equation can be rewritten to yield a temperature

compensated value for VIN:

()

(

)

GAIN

TEMP

DRIFT

VOS

OUT

25°

−

Figure 52 shows the output voltage and error (in dB) as a

function of input level for a typical device (note that output

voltage is plotted on a logarithmic scale). Figure 53 shows the

error in the calculated input level after the temperature

compensation algorithm has been applied. For a supply voltage

of 5 V, the part exhibits a worst-case linearity error over

temperature of approximately ±0.3 dB over a dynamic range of

35 dB.

PIN (dBm)

2.5

–25

–20

–15

–10

–5

1.0

2.0

1.5

0.5

510

+25°C

–40°C

–0.5

–1.0

–1.5

–2.0

–2.5

0.1

1.0

+85°C

Figure 52. Typical Output Voltage and Error vs.

Input Level, 800 MHz, VPOS = 5 V

PIN (dBm)

–25

–20

–15

–10

–5

1.0

2.0

1.5

0.5

510

–0.5

–1.0

–1.5

–2.0

–2.5

+25°C

–40°C

+85°C

–3.0

–30

Figure 53. Error after Temperature Compensation of

Output Reference,800 MHz, VPOS = 5 V

Extended Frequency Characterization

Although the AD8361 was originally intended as a power

measurement and control device for cellular wireless

applications, the AD8361 has useful performance at higher

frequencies. Typical applications may include MMDS, LMDS,

WLAN, and other noncellular activities.

In order to characterize the AD8361 at frequencies greater than

2.5 GHz, a small collection of devices were tested. Dynamic

range, conversion gain, and output intercept were measured at

several frequencies over a temperature range of −30°C to +80°C.

Both CW and 64 QAM modulated input wave forms were used

in the characterization process in order to access varying peak-

to-average waveform performance.

The dynamic range of the device is calculated as the input

power range over which the device remains within a

permissible error margin to the ideal transfer function. Devices

were tested over frequency and temperature. After identifying

an acceptable error margin for a given application, the usable

dynamic measurement range can be identified using the plots in

Figure 54 through Figure 57. For instance, for a 1 dB error

margin and a modulated carrier at 3 GHz, the usable dynamic

range can be found by inspecting the 3 GHz plot of Figure 57.

Note that the −30°C curve crosses the −1 dB error limit at

−17 dBm. For a 5 V supply, the maximum input power should

not exceed 6 dBm in order to avoid compression. The resultant

usable dynamic range is therefore

6 dBm − (−17 dBm)

or 23 dBm over a temperature range of −30°C to +80°C.

PIN (dBm)

2.5

–25

2.0

1.5

1.0

0.5

–0.5

–1.0

–1.5

–2.0

–2.5

–20

–15

–10

–5

0.1

+80°C

+25°C

–30°C

Figure 54. Transfer Function and Error Plots Measured at

1.5 GHz for a 64 QAM Modulated Signal

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