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ADS820

12

SBAS037B

FIGURE 6. A Low Distortion DC-Coupled, Single-Ended to Differential Input Driver Circuit.

FIGURE 7. A Wideband DC-Coupled, Single-Ended to Differential Input Driver Circuit.

604

Ω

301

Ω

301

Ω

301

Ω

604

Ω

49.9

Ω

301

Ω

604

Ω

2.49k

Ω

2.49k

Ω +2.25V

OPA842

OPA130

301

Ω

0.1

µF

OPA842

OPA842

+5V

–5V

+5V(2)

+5V

–5V

+5V

+5V

+5V

–5V

BAS16(1)

BAS16(1)

301

Ω

24.9

Ω

Input Level

Shift Buffer

Optional

High Impedance

Input Amplifier

DC-Coupled

Input Signal

26 IN

22 CM

27 IN

ADS820

NOTES: (1) A Philips BAS16 diode or equivalent may be used.

(2) Supply bypassing not shown. (3) OPA620 or OPA650 may be

substituted. See “Driving the ADS820” section.

22pF

22pF

604

Ω

0.1

µF

0.1

µF

(3)

(3)

(3)

50

Ω

1k

Ω

OTA

OPA860

OPA860

+1

+1

OPA130

1nF

OTA

+5V

–5V

–5V

+5V

DC-Coupled

Input Signal

27 IN

22 CM

26 IN

ADS820

NOTE: Power supplies and bypassing not shown. The measured SNR performance with 12.5MHz input signal is 57dB with this driver circuit.

1k

Ω

500

Ω

500

Ω

1k

Ω

200

Ω

243

Ω

200

Ω

3B

2

3

2

85

C

6

6

1

85

C

E

E

3

2

7

4

B

200

Ω

C

1

15pF

22pF

22pF

0.1

µF

2k

Ω

V

OUT

–5V

243

Ω