Philips Semiconductors

Product specification

NE/SA5204A

Wide-band high-frequency amplifier

1992 Feb 25

8

PC BOARD MOUNTING

In order to realize satisfactory mounting of the NE5204A 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

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

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 NE5204A 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.

NE5204A

VOUT

VIN

VCC

AC

COUPLING

CAPACITOR

RF CHOKE

DECOUPLING

CAPACITOR

AC

COUPLING

CAPACITOR

SR00210

Figure 18. Circuit Schematic for

Coupling and Power Supply Decoupling

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/SE5204A to

other high-frequency amplifiers.

of the power gain, and, in decibels, is equal to voltage gain as

shown below:

P

V

IN

2

Z

D

P

V

OUT

2

Z

D

N

P

OUT

P

IN

+

V

OUT

2

Z

D

V

IN

2

Z

D

+

V

OUT

2

V

IN

2

+ P

I

NE5204A

Measured value for the

NP

P

OUT

P

IN

+ |S

2

+ 100

and V

V

OUT

V

IN

+ P

I

+ S

In decibels:

Also measured on the same system are the respective voltage

standing wave ratios. These are shown in Figure 21. The VSWR

can be seen to be below 1.5 across the entire operational frequency

range.

Relationships exist between the input and output return losses and

the voltage standing wave ratios. These relationships are as follows: