Philips Semiconductors

Product specification

NE/SA/SE5205A

Wide-band high-frequency amplifier

1992 Feb 24

8

POWER DISSIPATION CONSIDERATIONS

When using the part at elevated temperature, the engineer should con-

sider the power dissipation capabilities of each package.

At the nominal supply voltage of 6V, the typical supply current is

25mA (32mA Max). For operation at supply voltages other than 6V,

inversely proportional to temperature and varies no more than 1mA

between 25

°C and either temperature extreme. The change is 0.1%

per over the range.

The recommended operating temperature ranges are air-mount

specifications. Better heat sinking benefits can be realized by

mounting the D package body against the PC board plane.

PC BOARD MOUNTING

In order to realize satisfactory mounting of the NE5205A to a PC

board, certain techniques need to be utilized. The board must be

double-sided with copper and all pins must be soldered to their

The power supply should be decoupled with a capacitor as close to

between the supply and the device. Caution should be exercised in

the connection of input and output pins. Standard microstrip should

be observed wherever possible. There should be no solder bumps

or burrs or any obstructions in the signal path to cause launching

problems. The path should be as straight as possible and lead

lengths as short as possible from the part to the cable connection.

Another important consideration is that the input and output should

approximately at 1V while the output is at 3.1V. The output must be

decoupled into a low impedance system or the DC bias on the

output of the amplifier will be loaded down causing loss of output

power. The easiest way to decouple the entire amplifier is by

soldering a high frequency chip capacitor directly to the input and

output pins of the device. This circuit is shown in Figure 18. Follow

these recommendations to get the best frequency response and

noise immunity. The board design is as important as the integrated

circuit design itself.

SCATTERING PARAMETERS

The primary specifications for the NE/SA/SE5205A are listed as

S-parameters. S-parameters are measurements of incident and

reflected currents and voltages between the source, amplifier and

load as well as transmission losses. The parameters for a two-port

network are defined in Figure 19.

Actual S-parameter measurements using an HP network analyzer

(model 8505A) and an HP S-parameter tester (models 8503A/B) are

shown in Figure 20.

Values for the figures below are measured and specified in the data

sheet to ease adaptation and comparison of the NE/SA/SE5205A to

other high-frequency amplifiers.

NE5205A

VOUT

VIN

VCC

AC

COUPLING

CAPACITOR

RF CHOKE

DECOUPLING

CAPACITOR

AC

COUPLING

CAPACITOR

SR00232

Figure 18. Circuit Schematic for Coupling and Power Supply

Decoupling

a. Two-Port Network Defined

b.

S21

S12

S22

S11

POWER AVAILABLE FROM

GENERATOR AT INPUT PORT

POWER REFLECTED

FROM INPUT PORT

S11 =

POWER REFLECTED

FROM OUTPUT PORT

POWER AVAILABLE FROM

GENERATOR AT OUTPUT PORT

REVERSE TRANSDUCER

POWER GAIN

S12 =

S11 — INPUT RETURN LOSS

S12 — REVERSE TRANSMISSION LOSS

OSOLATION

S21 — FORWARD TRANSMISSION LOSS

OR INSERTION GAIN

S21 =

TRANSDUCER POWER GAIN

S22 — OUTPUT RETURN LOSS

SR00233

Figure 19.