LLCC68 datasheet(28/111 Pages) SEMTECH

28 / 111 page

LLCC68

Data Sheet

Rev. 1.1

DS.LLCC68.W.APP

Dec 2024

28 of 111

Semtech

LLCC68

www.semtech.com

4.4.1 Power Amplifier Specifics

Caution!

All figures below are indicative and typical, and are not a specification. These figures only highlight behavior of the PA over voltage and

current.

Figures are given with DC-DC regulation enabled, which applies only to the circuit core.

The PA is optimized for maximum output power whilst maximizing the efficiency, which makes it mandatory to supply the power amplifier

with fairly high voltages to maintain an high output power. To summarize:

• The current efficiency of the PA is optimal at the highest output power step

• Output power is limited by the voltage supplied to VBAT

This is illustrated in the following figure:

Figure 4-4: VR_PA versus Output Power on the LLCC68

The internal regulator for VR_PA has a little less than 200mV of drop-out, which means VBAT must be 200mV higher than the published

VR_PA voltages in order to attain the corresponding output power. For example, for Pout = +20dBm, VR_PA = 2.5V is required, which means

that the LLCC68 is able to maintain Pout = +20dBm on the 2.7V < VBAT < 3.7V voltage range. Below 2.7V, the output power degrades as VBAT

reduces.

As can be seen from the blue curve on Figure 4-4: VR_PA versus Output Power on the LLCC68, the LLCC68 is capable of supplying almost

1.7V when VBAT = 1.8V, which, in turn, makes the output power plateau at +17dBm for all power settings above +17dBm.

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