THS3095D datasheet(32/55 Pages) TI

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As shown in Figure 9-9 for example, in a two-amplifier load sharing configuration with matching resistance

driving a resistive load (RL), each series resistance is 2*RL and each amplifier drives 2*RL. A convenient

indicator of whether an op amp will function well in a load sharing configuration is the characteristic performance

graph of harmonic distortion versus load resistance. Such graphs can be found in most of TI’s high-speed

amplifier data sheets. These graphs can be used to obtain a general sense of whether or not an amplifier will

show improved distortion performance in load sharing configurations.

Figure 9-9 shows two test circuits: one for a single THS3091 amplifier driving a double-terminated (50-Ω cable),

and one with two THS3091 amplifiers in a load sharing configuration. In the load sharing configuration, the two

100-Ω series output resistors act in parallel to provide 50-Ω back-matching to the 50-Ω cable.

Figure 9-10 and Figure 9-11 show the 32-MHz, 18-VPP sine wave output amplitudes for the single THS3091

configuration and the load sharing configuration, respectively, measured using an oscilloscope. An ideal sine

wave is also included as a visual reference (the dashed red line). Figure 72 shows visible distortion in the single

THS3091 output. In the load sharing configuration of Figure 73, however, no obvious degradation is visible.

Figure 9-12 and Figure 9-13 show the 64-MHz sine wave outputs of the two configurations from Figure 8. While

the single THS3091 output is clearly distorted in Figure 74, the output of the load sharing configuration in Figure

75 shows only minor deviations from the ideal sine wave.

The improved output waveform as a result of load sharing is quantified in the harmonic distortion versus

frequency graphs shown in Figure 9-14 and Figure 9-15 for the single amplifier and load sharing configurations,

respectively. While second-harmonic distortion remains largely the same between the single and load sharing

cases, third-harmonic distortion is improved by approximately 8 dB in the frequency range between 20 MHz to

64 MHz.

Table 9-2. Bill of Materials

THS3091DDA and THS3095DDA EVM(1)

ITEM

DESCRIPTION

SMD

SIZE

REFERENCE

DESIGNATOR

PCB

QTY

MANUFACTURER'S

PART NUMBER

DISTRIBUTOR'S

PART NUMBER

Bead, Ferrite, 3 A, 80 Ω

1206

FB1, FB2

(Steward) HI1206N800R-00

(Digi-Key) 240-1010-1-ND

Cap, 6.8 μF, Tantalum, 50 V, 10%

C3, C6

(AVX) TAJD685K050R

(Garrett) TAJD685K050R

Cap, 0.1 μF, ceramic, X7R, 50 V

0805

C9, C10

2(2)

(AVX) 08055C104KAT2A

(Garrett) 08055C104KAT2A

Cap, 0.1 μF, ceramic, X7R, 50 V

0805

C4, C7

(AVX) 08055C104KAT2A

(Garrett) 08055C104KAT2A

Resistor, 0 Ω, 1/8 W, 1%

0805

1(2)

(KOA) RK73Z2ALTD

(Garrett) RK73Z2ALTD

Resistor, 249 Ω, 1/8 W, 1%

0805

(KOA) RK73H2ALTD2490F

(Garrett) RK73H2ALTD2490F

Resistor, 1 kΩ, 1/8 W, 1%

0805

(KOA) RK73H2ALTD1001F

(Garrett) RK73H2ALTD1001F

Open

1206

Resistor, 0 Ω, 1/4 W, 1%

1206

(KOA) RK73Z2BLTD

(Garrett) RK73Z2BLTD

Resistor, 49.9 Ω, 1/4 W, 1%

1206

R2, R7

(KOA) RK73Z2BLTD49R9F

(Garrett) RK73Z2BLTD49R9F

Open

2512

R5, R6

Header, 0.1-inch (2,54 mm) centers,

0.025-inch (6,35 mm) square pins

JP1, JP2

2 (2)

(Sullins) PZC36SAAN

(Digi-Key) S1011-36-ND

Connector, SMA PCB Jack

J1, J2, J3

(Amphenol) 901-144-8RFX

(Newark) 01F2208

Jack, banana receptacle,

0.25-inch (6,35 mm) dia. hole

J4, J5, J6

(SPC) 813

(Newark) 39N867

Test point, black

TP1, TP2

(Keystone) 5001

(Digi-Key) 5001K-ND

Standoff, 4-40 hex,

0.625-inch (15,9 mm) length

(Keystone) 1808

(Newark) 89F1934

Screw, Phillips, 4-40,

0.25-inch (6,35 mm)

SHR-0440-016-SN

IC, THS3091(3)

IC, THS3095(2)

(TI) THS3091DDA(3)

(TI) THS3095DDA(2)

Board, printed-circuit

(TI) EDGE # 6446289 Rev. A(3)

(TI) EDGE # 6446290 Rev. A(2)

(1)

All items are designated for both the THS3091DDA and THS3095 EVMs unless otherwise noted.

(2)

THS3095 EVM only.

(3)

THS3091 EVM only.

THS3091, THS3095

SLOS423I – SEPTEMBER 2003 – REVISED DECEMBER 2022

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