THS4513 datasheet(23/34 Pages) TI

23 / 34 page

www.ti.com

TEST CIRCUITS

Output Measured

Here With High

Impedance

Differential Probe

THS4513

VIN

RIT

From

Ω

Source

VS+

VS−

49.9

Ω

49.9

Ω

100

Ω

0.22

µF

49.9

Ω

0.22

µF

Open

Distortion and 1dB Compression

Frequency Response

THS 4513

From

Ω

Source

VIN

0.22

µF

49.9

Ω

VOUT

Open

To 50

Ω

Test

Equipment

RIT

VS+

VS−

ROT

0.22

µF

1:1

THS4513

SLOS472 – AUGUST 2005

The output is probed using a high-impedance differ-

ential probe across the 100-

Ω resistor. The gain is

The THS4513 is tested with the following test circuits

referred to the amplifier output by adding back the

built on the EVM. For simplicity, power supply de-

6-dB loss due to the voltage divider on the output.

coupling is not shown – see layout in the applications

section for recommendations. Depending on the test

conditions, component values are changed per the

following tables, or as otherwise noted. The signal

generators used are ac coupled 50-

Ω sources and a

0.22-µF capacitor and a 49.9-

Ω resistor to ground are

inserted across RIT on the alternate input to balance

the circuit. A split power supply is used to ease the

interface to common test equipment, but the amplifier

can be operated single-supply as described in the

applications section with no impact on performance.

Figure 71. Frequency Response Test Circuit

Table 1. Gain Component Values

GAIN

RIT

0 dB

348

Ω

340

Ω

56.2

Ω

The circuit shown in Figure 72 is used to measure

6 dB

348

Ω

66.5

Ω

61.4

Ω

harmonic distortion, intermodulation distortion, and

1-db compression point of the amplifier.

Note the gain setting includes 50-

Ω source im-

pedance. Components are chosen to achieve gain

A signal generator is used as the signal source and

and 50-

Ω input termination.

the output is measured with a spectrum analyzer. The

output impedance of the signal generator is 50

Ω. R

Table 2. Load Component Values

and RG are chosen to impedance-match to 50 Ω, and

to maintain the proper gain. To balance the amplifier,

ROT

Atten.

a 0.22-µF capacitor and 49.9-

Ω resistor to ground are

100

Ω

open

6 dB

inserted across RIT on the alternate input.

200

Ω

86.6

Ω

69.8

Ω

16.8 dB

A low-pass filter is inserted in series with the input to

499

Ω

237

Ω

56.2

Ω

25.5 dB

reduce harmonics generated at the signal source.

Ω

487

Ω

52.3

Ω

31.8 dB

The level of the fundamental is measured, then a

high-pass filter is inserted at the output to reduce the

Note the total load includes 50-

Ω termination by

fundamental so that it does not generate distortion in

the test equipment. Components are chosen to

the input of the spectrum analyzer.

achieve load and 50-

Ω line termination through a

1:1 transformer.

The transformer used in the output to convert the

signal

from

differential

single

ended

Due to the voltage divider on the output formed by

ADT1-1WT. It limits the frequency response of the

the load component values, the amplifier's output is

circuit so that measurements cannot be made below

attenuated. The column Atten in Table 2 shows the

approximately 1MHz.

attenuation expected from the resistor divider. When

using a transformer at the output as shown in

Figure 72, the signal will see slightly more loss, and

these numbers will be approximate.

The circuit shown in Figure 71 is used to measure the

frequency response of the circuit.

A network analyzer is used as the signal source and

as the measurement device. The output impedance

of the network analyzer is 50

Ω. R

IT and RG are

Figure 72. Distortion Test Circuit

chosen to impedance match to 50

Ω, and to maintain

the proper gain. To balance the amplifier, a 0.22-µF

The 1-dB compression point is measured with a

capacitor and 49.9-

Ω resistor to ground are inserted

spectrum analyzer with 50-

Ω double termination or

across RIT on the alternate input.

THS4513 Datasheet(PDF) 23 Page - Texas Instruments

THS4513 Datasheet(HTML) 23 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

Datasheet Download

Link URL