ADL5906ACPZN-R7 datasheet(25/30 Pages) AD

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Data Sheet

ADL5906

THEORY OF OPERATION

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Rev. B | 25 of 30

As shown in Figure 54, whereas the slope is stable vs. the tempera-

ture at 2140 MHz, the intercept of the ADL5906 does vary slightly

vs. temperature (approximately +0.3 dB at +85°C and −0.8 dB at

−40°C). This variation in intercept is constant vs. input power level

at most frequencies. Table 7 lists the average temperature coeffi-

cient of VRMS in mV/°C at frequencies from 100 MHz to 5.8 GHz.

This temperature coefficient is given by the following equation:

TCVRMS = (DRIFTVRMS/ΔTEMP) × Slope

(18)

where:

DRIFTVRMS is the specified drift of VRMS (scaled in dB) from ambi-

ent to either −40°C or +85°C at an input power level of 0 dBm (see

Table 1).

∆TEMP is equal to either +65°C for cold drift (that is, +25°C −

(−40°C)) or +60°C for hot drift (that is, +85°C − +25°C).

Slope is the specified slope of VRMS (see Table 1).

For example, at 2.14 GHz, TCVRMS for hot drift can be calculated as

TCVRMS = (0.3 dB/60°C) × 56 mV/dB = 0.28 mV/°C

The value for slope that is used can also be the slope that is

calculated during device calibration. This gives results that are

slightly more accurate because there is slight variation in slope from

device to device.

Table 7 also lists the typical temperature coefficient of the VTEMP

temperature sensor output. To calculate the appropriate amount of

compensation required at a particular frequency, a VTEMP weighting

factor is calculated. This is simply the ratio of the temperature

coefficients of VTEMP and VRMS. These weighting factors are also

shown in Table 7.

Using the data shown in Table 7, an adjusted value for VRMS

(VRMS′) can be calculated using the following equation:

VRMS′=VRMS− VTEMP−VTEMP25

Weigℎting Factor

(19)

where:

VTEMP25 is equal to the voltage measured on VTEMP during system

calibration at ambient temperature.

VTEMP is equal to the voltage on VTEMP during normal operation.

Figure 55 to Figure 62 show typical plots of VRMS′ vs. input level

and temperature at frequencies from 100 MHz to 5.8 GHz when this

temperature compensation algorithm is applied.

From a system calibration and operation perspective, the only addi-

tional measurements that are required to implement this algorithm

are measurement and storage of VTEMP during calibration (that is,

at ambient temperature) and measurement of VTEMP during opera-

tion. All other information required to implement this algorithm (that

is, nominal temperature drift of VRMS and temperature coefficient of

VTEMP) is based on typical data sheet specifications.

Figure 55. VRMS′ and Log Conformance Error vs. Input Level and

Temperature at 100 MHz Using VTEMP Intercept Compensation

Figure 56. VRMS′ and Log Conformance Error vs. Input Level and

Temperature at 700 MHz Using VTEMP Intercept Compensation

Figure 57. VRMS′ and Log Conformance Error vs. Input Level and

Temperature at 900 MHz Using VTEMP Intercept Compensation

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