AN2048

Circuit design and considerations

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3

Circuit design and considerations

The PD54008L-E is an 8 W - 7 V LDMOS housed in a PowerFLAT plastic package (5x5

mm).

Being an internally unmatched device, the PD54008L-E can be used in different portable

applications over HF, VHF & UHF frequency bands.

Table 1 shows the source and load impedances of the PD54008L-E at 500 MHz.

Figure 4.

Source and load impedances of PD54008L-E

The above impedances are taken as a starting point to design the input and output matching

networks of the PD54008L-E amplifier. Microstrip lines and lumped elements are used.

3.1

Amplifier construction

The PCB is made of double-sided copper-clad fiberglass (THK 0.020") with the lowest

dielectric constant (

εr = 2.17) and dissipation factor available. The printed circuit board is

glued to copper for dissipation purposes.

Figure 5.

Device footprint

Table 1.

Source and load impedances of PD54008L-E at 500 MHz

F (MHz)

Z1 (

Ω)Z2 (Ω)

500

0.3+j2.0

1.8+j0.7