HMC8415LP6GETR datasheet(21/23 Pages) AD

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Data Sheet

HMC8415LP6GE

Rev. A | Page 21 of 23

MAKING AVERAGE TO PULSED APPROXIMATIONS

To measure RF power, IDD, and PAE accurately in a pulsed

manner, use instruments offering pulse triggered measurements.

When pulse triggered instruments are not available but simpler

instruments with adequate averaging capabilities are, approximations

can be made with the understanding that the approximations

can result in lower accuracy of measurement. The most

common approximations involve measuring the average values

of parameters and then adjusting those values to account for the

duty cycle of operation. Approximating in this manner can

result in errors due to the limited measurement bandwidths of

the instruments and/or the inclusion of on/off transients and/or

partial periods in the measurement. So that partial periods do

not contribute significant errors to the measurements, perform

the averaging over a large number of pulse periods. The results

of such approximations can vary with the instruments and

settings used. Therefore, experimentation can be necessary to

achieve credible and repeatable results. When it is not possible

to make pulse triggered measurements, the only pulse connection

required is the one from the pulse generator to the J1 connector

of the pulsor (see Figure 49).

Depending on the implementation of the HMC8415LP6GE and

the pulsor into customer applications, adjustments of the pulse

circuit may be desired if the on and off transitions are accompanied

by excessive drain supply ringing. Synchronous with the drain

pulses, the VGGxx bias and RFIN signal can also be pulsed.

Unless otherwise noted, all measurement data shown within

this data sheet was taken using the typical application circuit

(see Figure 47) as implemented on the evaluation board (see

Figure 50), with the drain bias pulsed at 28 V by the pulsor

board (see Figure 48) to achieve the nominal IDQ of 1000 mA

at a pulse width of 100 µs, and 10% duty cycle. Operating at

different drain voltages or different drain quiescent currents

affects performance, as shown in the Typical Performance

Characteristics section. For applications having lower power

and gain requirements, operation at lower VDDxx and IDQ can

help reduce power consumption. Due to thermal considerations,

the use of lower duty cycles and shorter pulse widths can

sometimes result in improved power and PAE.

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