THS4513 datasheet(28/34 Pages) TI

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THS4513 + ADS5424 Combined Performance

2.7 pF

0.1 F

-bit,

125 MSPS

A IN +

A IN - CM

ADS5500

4 V

THS 4513

348 W

340 W

56.2 W

VIN

From

50-

source

100 W

-1 V

56.2 W

49.9 W

0.22 F

49.9 W

0.22 F

0.1 F

2 7 pF

0.1 F

14 -bit,

105 MSPS

A IN+

A IN

–

VBG

ADS 5424

5 V

THS4513

348 W

340 W

340

VIN

From

50-

source

225 W

56.2 W

49.9 W

49 .9 W

0.22 F

0.1 F

0.22 F

THS4513

SLOS472 – AUGUST 2005

inserted to ground across the 69.8-

Ω resistor and

0.22-µF capacitor on the alternate input to balance

the circuit. Gain is a function of the source im-

pedance, termination, and 348-

Ω feedback resistor.

Refer to Table 3 for component values to set proper

50-

Ω termination for other common gains. A split

power supply of +4V and -1V is used to set the input

and output common-mode voltages to approximately

mid-supply while setting the input common-mode of

the ADS5500 to the recommended +1.55V. This

maintains maximum headroom on the internal transis-

tors of the THS4513 to insure optimum performance.

Figure 85. THS4513 + ADS5500 2-Tone FFT with

65 MHz and 70 MHz Input

Figure 86 shows the THS4513 driving the ADS5424

Figure 84. THS4513 + ADS5500 Circuit

ADC.

As before, the THS4513 amplifier provides 10 dB of

Figure 85 shows the 2-tone FFT of the THS4513 +

gain, converts the single-ended input to differential,

ADS5500 circuit with 65 MHz and 70 MHz input

and sets the proper input common-mode voltage to

frequencies. The SFDR is 90 dBc.

the ADS5424. Input termination and circuit testing is

the same as described above for the THS4513 +

ADS5500 circuit.

The 225-

Ω resistors and 2.7-pF capacitor between

the THS4513 outputs and ADS5424 inputs (along

with the input capacitance of the ADC) limit the

bandwidth of the signal to about 100MHz (-3dB).

Since the ADS5424s recommended input com-

mon-mode voltage is 2.4 V, the THS4513 is operated

from a single power supply input with VS+ = 5 V and

VS– = 0 V (ground).

Figure 86. THS4513 + ADS5424 Circuit

THS4513 Datasheet(PDF) 28 Page - Texas Instruments

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