THS0842

DUAL-INPUT, 8-BIT, 40 MSPS LOW-POWER ANALOG-TO-DIGITAL CONVERTER

WITH SINGLE OR DUAL PARALLEL BUS OUTPUT

SLAS246 – DECEMBER 1999

23

POST OFFICE BOX 655303

PRINCIPLES OF OPERATION

analog input, single-ended connection (continued)

The single ended analog input can be dc coupled (Figure 24) as long as the input is within the analog input

common mode voltage range. A capacitor, C, connected from I/Q IN+ to I/Q IN– will help filter any high frequency

noise on the inputs, also improving performance. Note, that the value of capacitor C chosen must take into

account the highest frequency component of the analog input signal.

1.5 V

2 V

Single

Ended

Input

1 V

1.0 Vp–p

Figure 22. Single-Ended Input Waveform

A single-ended source may give better overall system performance if it is first converted to differential before

driving the THS0842.

THS0842

CML

R

AIN+

R

C1

C2

VIN

AIN–

REFT

REFB

VBIAS

+

Figure 23. AC-Coupled Input