CDS-1402 Datel, Inc., CDS-1402 Datasheet

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CDS-1402

Manufacturer Part Number
CDS-1402
Description
Faster-settling Correlated Double Sampling Circuit: 14-bit
Manufacturer
Datel, Inc.
Datasheet
DATEL, Inc., 11 Cabot Boulevard, Mansfield, MA 02048-1151 (U.S.A.)
FEATURES
GENERAL DESCRIPTION
The CDS-1402 is an application-specific, correlated double
sampling (CDS) circuit designed for electronic-imaging
applications that employ CCD's (charge coupled devices) as
their photodetector. The CDS-1402 has been optimized for
use in digital video applications that employ 10 to 14-bit A/D
converters. The low-noise CDS-1402 can accurately
determine each pixel's true video signal level by sequentially
sampling the pixel's offset signal and its video signal and
subtracting the two. The result is that the consequences of
residual charge, charge injection and low-frequency "kTC"
noise on the CCD's output floating capacitor are effectively
eliminated. The CDS-1402 can also be used as a dual
sample-hold amplifier in a data acquisition system.
The CDS-1402 contains two sample-hold amplifiers and
appropriate support/control circuitry. Features include
independent offset-adjust capability for each S/H,
adjustment for matching gain between the two S/H's,
Use with 10 to 14-bit A/D converters
5 Megapixels/second minimum throughput (14 bits)
±2.5V input/output ranges, Gain = –1
Low noise, 200µVrms
Two independent S/H amplifiers
Gain matching between S/H's
Offset adjustments for each S/H
Four external A/D control lines
Small package, 24-pin ceramic DDIP
Low power, 350mW
Low cost
®
OFFSET ADJUST V1
OFFSET ADJUST V2 9
DO NOT CONNECT
DO NOT CONNECT 10
ANALOG INPUT 1
ANALOG INPUT 2
S/H1 COMMAND 11
S/H2 COMMAND 12
1
2
3
4
ANALOG GROUND
5, 14, 21, 23
®
100k
100k
500
500
Figure 1. CDS-1402 Functional Block Diagram
+5V ANALOG
SUPPLY
24
Tel: (508) 339-3000 Fax: (508) 339-6356
+
+
S/H 1
S/H 2
450
500
500
C
Correlated Double Sampling Circuit
C
H
–5V ANALOG
H
SUPPLY
and four control lines for triggering the A/D converter used in
conjunction with the CDS-1402. The CDS circuit's "ping-
pong" timing approach (the offset signal of the "n+1" pixel can
be acquired while the video output of the "nth" pixel is being
converted) guarantees a minimum throughput, in a 14-bit
application, of 5MHz. In other words, the true video signal
(minus offset) will be available
13
PIN
10
11
12
1
2
3
4
5
6
7
8
9
OFFSET ADJUST V1
DO NOT CONNECT
ANALOG INPUT 1
ANALOG INPUT 2
ANALOG GROUND
S/H1 OUT
S/H1 ROUT
S/H2 SUMMING NODE
OFFSET ADJUST V2
DO NOT CONNECT
S/H1 COMMAND
S/H2 COMMAND
FUNCTION
+5V DIGITAL
SUPPLY
16
INPUT/OUTPUT CONNECTIONS
14-Bit, Very Fast Settling
50
GROUND
DIGITAL
15
For immediate assistance: (800) 233-2765
7
6
22 V OUT
18 A/D CLOCK 1
19 A/D CLOCK 2
8
17 A/D CLOCK 1
20 A/D CLOCK 2
S/H1 OUT
S/H1 ROUT
PIN FUNCTION
S/H2
SUMMING NODE
24
23
22
21
20
19
18
17
16
15
14
13
CDS-1402
OPTIONAL
+5V ANALOG SUPPLY
ANALOG GROUND
V OUT
ANALOG GROUND
A/D CLOCK2
A/D CLOCK2
A/D CLOCK1
A/D CLOCK1
+5V DIGITAL SUPPLY
DIGITAL GROUND
ANALOG GROUND
–5V ANALOG SUPPLY
(continued on page 3)

Related parts for CDS-1402

CDS-1402 Summary of contents

Page 1

... The result is that the consequences of residual charge, charge injection and low-frequency "kTC" noise on the CCD's output floating capacitor are effectively eliminated. The CDS-1402 can also be used as a dual sample-hold amplifier in a data acquisition system. The CDS-1402 contains two sample-hold amplifiers and appropriate support/control circuitry ...

Page 2

... Logic Loading "0" — Pins 3 and 4. See Figure 4 for relationship between input voltage, accuracy, and acquisition time. PHYSICAL/ENVIRONMENTAL PARAMETERS UNITS Operating Temp. Range, Case Volts CDS-1402MC Volts CDS-1402MM Volts Thermal Impedance +0.3 Volts jc Volts ca °C Storage Temperature Range Package Type Weight +25° ...

Page 3

... Funtional Description ), the circuit actually exploits an elegant architecture whose tradeoffs enable it to offer wide-bandwidth, low-noise and high-throughput combinations unachievable until now. The CDS-1402, a generic type of circuit, can be used with most 10 to 14-bit A/D converters. However, DATEL offers A/D converters optimized for use with CDS-1402. ...

Page 4

... The DATEL CDS-1402 takes a slightly different, though clearly superior, approach to CDS. It can be called the "sample- subtract-sample" approach. Note that the CDS-1402 has been configured to offer the greatest amount of user flexibility. Its two S/H circuits function independently. They have separate input and output pins. ...

Page 5

... EOC OUTPUT DATA N-1 VALID DATA Figure 3. CDS-1402 in Front of DATEL's ADC-944 at f Timing Notes See Figure 2, Typical Timing Diagram advisable that neither of the CDS-1402's S/H amplifiers be in their sample/ track mode when large, high-speed transients (normally associated with clock edges) are occurring throughout the system ...

Page 6

... A/D CLOCK2 (pin 19 delayed version of the signal applied to pin 12 (S/H2 COMMAND), and A/D CLOCK2 (pin 20) is its complement. Any one of these signals, as appropriate, may be used to trigger the A/D conversion. Figure typical timing diagram for a CDS-1402 in front of DATEL's 14-bit, 5MHz sampling A/D, the ADS-944 ...

Page 7

... A/D CLOCK 2 6 S/H1 OUT A/D CLOCK 1 7 S/H1 ROUT A/D CLOCK 1 8 S/H2 SUMMING NODE +5V DIGITAL SUPPLY 9 OFFSET ADJUST V2 DIGITAL GROUND 10 ANALOG GROUND DO NOT CONNECT 11 S/H1 COMMAND 12 –5V ANALOG SUPPLY S/H2 COMMAND Figure 5. CDS-1402 Typical Connection Diagram 7 CDS-1402 24 +5V + 0.1µF 2.2µ +5V + 0.1µF 2.2µ – ...

Page 8

... Kovar alloy ateria Lead Finish: 50 microinches (minimum) gold plating over 100 microinches (nominal) nickel plating 0.060 TYP. 0.015 (1.524) (0.381) MAX. radius 0.130 TYP. for any pin (3.302) 0.020 0.010 TYP. (0.508) (0.254) Heat Sink for all CDS-1402 DDIP models ® DS-0345 08/96 ...

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