12-Bit, 20MHz Sampling

ANALOG-TO-DIGITAL CONVERTER

FEATURES

q HIGH SFDR: 74dB at 9.8MHz f

IN

q HIGH SNR: 68dB

q LOW POWER: 300mW

q LOW DLE: 0.25LSB

q FLEXIBLE INPUT RANGE

q OVER-RANGE INDICATOR

APPLICATIONS

q STUDIO CAMERAS

q IF AND BASEBAND DIGITIZATION

q COPIERS

q TEST INSTRUMENTATION

DESCRIPTION

The ADS805 is a 20MHz, high dynamic range, 12-bit, pipelined

Analog-to-Digital Converter ADC. This converter includes a

high-bandwidth track-and-hold that gives excellent spurious

performance up to and beyond the Nyquist rate. This high-

bandwidth, linear track-and-hold minimizes harmonics and

has low jitter, leading to excellent Signal-to-Noise Ratio

(SNR) performance. The ADS805 is also pin-compatible with

the 10MHz ADS804 and the 5MHz ADS803.

The ADS805 provides an internal reference or an external

reference can be used. The ADS805 can be programmed for

a 2Vp-p input range which is the easiest to drive with a single

op amp and provides the best spurious performance. Alter-

natively, the 5Vp-p input range can be used for the lowest

input-referred noise of 0.09LSBs rms giving superior imaging

performance. There is also the capability to set the input

range between 2Vp-p and 5Vp-p, either single-ended or

differential. The ADS805 also provides an over-range flag

that indicates when the input signal has exceeded the

converter’s full-scale range. This flag can also be used to

reduce the gain of the front end signal conditioning circuitry.

The ADS805 employs digital error techniques to provide

excellent differential linearity for demanding imaging applica-

tions. Its low distortion and high SNR give the extra margin

needed for communications, medical imaging, video, and

test instrumentation applications. The ADS805 is available in

an SSOP-28 package.

12-Bit

Pipelined

ADC Core

Reference and

Mode Select

Reference Ladder

and Driver

Timing Circuitry

Error

Correction

Logic

3-State

Outputs

T&H

D0

D11

•

•

•

CLK

+V

S

ADS805

VDRV

OE

SEL

REFB

V

REF

REFT

IN

V

IN

IN

CM

OVR

ADS805

SBAS073B – JANUARY 1997 – REVISED NOVEMBER 2002

www.ti.com

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

Copyright © 1997, Texas Instruments Incorporated

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

ADS8

05E