AX5051 datasheet(11/44 Pages) ONSEMI

11 / 44 page

Specifications

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AX5051

Note on current consumption in TX mode

To achieve best output power the matching network has to be optimized for the desired

output power and frequency. As a rule of thumb a good matching network produces

about 50% efficiency with the AX5051 power amplifier although over 90% are

theoretically possible. A typical matching network has between 1 dB and 2 dB loss (Ploss).

The current consumption can be calculated as

ITX[mA]=1/PAefficiency*10^((Pout[dBm]+Ploss[dB])/10)/2.5V+Ioffset

Ioffset is about 12 mA for the VCO at 400-470 MHz and 11 mA for 800-940 MHz. The

following table shows calculated current consumptions versus output power for Ploss = 1

dB, PAefficiency = 0.5 and Ioffset= 11 mA at 868 MHz

Pout [dBm]

I [mA]

13.0

13.2

13.6

14.0

14.5

15.1

16.0

17.0

18.3

20.0

22.0

24.6

27.96

32.1

37.3

43.8

The AX5051 power amplifier runs from the regulated VDD supply and not directly from

the battery. This has the advantage that the current and output power do not vary much

over supply voltage and temperature from 2.55 V to 3.6 V supply voltage. Between 2.55

V and 2.2 V a drop of about 1 dB in output power occurs.

AX5051 Datasheet(PDF) 11 Page - ON Semiconductor