SPT SPT7936SCT Datasheet

SPT7936

12-BIT, 28 MSPS SAMPLING A/D CONVERTER

FEATURES

• 3.0-3.6 V Power Supply

• Typical SINAD: 60 dB for (f

= 10 MHz)

IN

• Low power: (260 mW @3.3 V)

• Sample Rate: 28 MSPS

• Internal Sample/Hold

• Differential Input

• Sleep Mode (Power Down)

GENERAL DESCRIPTION

The SPT7936 is a compact, high-speed, low power 12-bit
monolithic analog-to-digital converter, implemented in a

0.5 µm CMOS process. The converter includes sample and
hold. The full scale range can be set between ±0.6 V and ±1.2
V using external references. It operates from a single 3.0-3.6
V supply-compatible with modern digital systems. Most con­verters in this performance range demand at least a +5 V
supply. Its low distortion and high dynamic range offers the

BLOCK DIAGRAM

BGAP

APPLICATIONS

• Imaging

• Test Equipment

• Computer Scanners

• Communications

• Set-Top Boxes

performance needed for demanding imaging, multimedia,
telecommunications and instrumentation applications.

The SPT7936 has a pipelined architecture - resulting in low
input capacitance. Digital error correction of the 11 most
significant bits ensures good linearity for input frequencies
approaching Nyquist.

The device is available in a 44L TQFP package over the
commercial temperature range of 0 to +70 °C.

Bias 0 Bias 1 CM

Ext Ref
V

REF

V

REF
VIN+

VIN-

Clock

Ref Buff

Ref Buff

+

-

THA

Clock
Driver

Stage 1 Stage 2 Stage 3 Stage 10

BGREF BIAS CELL

Digital Delays, Error Correction and Output Register

OR Bit <11...0)

Stage_Last

(2-Bit Flash)

Signal Processing Technologies, Inc.

4755 Forge Road, Colorado Springs, Colorado 80907, USA

Phone: [phone] FAX: [phone] Website: http://www.spt.com E-Mail: [e-mail]

ABSOLUTE MAXIMUM RATINGS (Beyond which damage may occur)1 25 °C

Supply Voltages

V

...................................................................

DD

1

V

...................................................................

DD

2

- 0.3 V to +6 V

- 0.3 V to +6 V

Temperatures

Operating Temperature ................................. 0 to +70 °C

Storage Temperature...............................- 65 to +125 °C

Input Voltages

Analog In....................................... - 0.3 V to VDD + 0.3 V

Digital In ........................................ - 0.3 V to VDD + 0.3 V

REF

....................................................

P

REF

....................................................

N

- 0.3 V to VDD + 0.3 V

- 0.3 V to VDD + 0.3 V

CLOCK.......................................... - 0.3 V to VDD + 0.3 V

Note: 1. Operation at any Absolute Maximum Rating is not implied. See Electrical Specifications for proper nominal

applied conditions in typical applications.

ELECTRICAL SPECIFICATIONS

TA = T

MIN-TMAX

specified.

PARAMETERS CONDITIONS LEVEL MIN TYP MAX UNITS

DC Accuracy

Differential Nonlinearity (DNL) VI ±0.5 ±1.0 LSB
Integral Nonlinearity VI ±1.3 ±3.0 LSB
Common Mode Rejection Ratio (CMRR) V 54 dB
No Missing Codes Guaranteed

, V

DD

=V

= 3.3 V, Sampling Rate = 28 MSPS, Differential input signal, 50% duty cycle clock with 2.5 ns rise and fall times, unless otherwise

DD

1

2

TEST TEST SPT7936

Analog Input

Input Voltage Range (differential) VFSR IV 0.6 ±1 ±1.2 V
Common Mode Input Voltage VCMI IV 1.2 1.5 1.6 V
Input Capacitance C

(From Each Input to Ground)
Midscale Offset V
Gain Error V -0.2 %

Input Bandwidth Large Signal V 150 MHz

Reference Voltages

Internal Reference Voltage on Pin 10 (V
Internal Reference Voltage on Pin 11 (V
Internal Reference Voltage Drift IV 100 ppm/°C
Negative Input Voltage (V
Positive Input Voltage (V
Reference Input Voltage Range (V
Common Mode Output Voltage (VCM) VI 1.45 1.50 1.55 V
Bandgap Output Voltage (V

Dynamic Performance

Effective Number of Bits f
Signal to Noise and Distortion Ratio (SINAD) fIN = 5.0 MHz V 62 dB
Signal to Noise Ratio (SNR) fIN = 5.0 MHz V 64 dB

Without Harmonics fIN = 10.0 MHz VI 59 63 dB

Total Harmonic Distortion (THD) fIN = 5.0 MHz V –66 dB

OS

IN

VIN+=VIN–=V

) VI 0.95 1.0 1.05 V

REFNI

) VI 1.95 2.0 2.05 V

REFPI

-) VI 0.9 1.0 1.3 V

REF

+) VI 1.9 2.0 2.3 V

REF

BGAP

+ — V

REF

) VI 2.365 2.415 2.465 V

-) IV 0.6 1.0 1.2 V

REF

= 5.0 MHz V 10.0 Bits

IN

fIN = 10.0 MHz VI 9.2 9.7 Bits
fIN = 10.0 MHz VI 57 60 dB

fIN = 10.0 MHz VI –64 –61 dB

CM

V2pF
V ±2%

SPT

SPT7936

2 8/1/00

ELECTRICAL SPECIFICATIONS

TA = T

MIN-TMAX

specified.

PARAMETERS CONDITIONS LEVEL MIN TYP MAX UNITS

Dynamic Performance

Spurious Free Dynamic Range (SFDR) f
Differential Phase (DP) V 0.08 degrees

Differential Gain (DG) V 0.27 %

Digital Inputs

Logic 0 Voltage (V
Logic 1 Voltage (VIH) VI 80% V
Logic 0 Current (IIL) (VI=VSS)VI ±1 µA
Logic 1 Current (IIH)(V
Input Capacitance (C

Digital Outputs

Logic 0 Voltage (V
Logic 1 Voltage (VOH) (I = -2 mA) VI 85% V
Output Hold Time (tH)V5ns
Output Delay Time (tD)V8ns

Switching Performance

Maximum Conversion Rate (f
Minimum Conversion Rate IV 1 MSPS
Pipeline Delay (See Timing Diagram) IV 8.0 Clocks
Aperture Jitter σ
Aperture Delay t

Power Supply

Supply Voltage V
Supply Current I

ext ref VI 75 87 mA
int ref VI 79 91 mA

Power Dissipation P

ext ref VI 248 288 mW
int ref VI 260 300 mW

Sleep Mode Current

ext ref VI 8 9 mA
int ref VI 11 12 mA

Sleep Mode Power Dissipation

ext ref VI 25 29 mW
int ref VI 36 40 mW

Power Supply Rejection Ratio (PSRR) V 52 dB

, V

=V

DD

= 3.3 V, Sampling Rate = 28 MSPS, Differential input signal, 50% duty cycle clock with 2.5 ns rise and fall times, unless otherwise

DD

1

2

TEST TEST SPT7936

= 5.0 MHz V 67 dB

IN

fIN = 10.0 MHz VI 62 64 dB

) VI 20% V

IL

DD

)VI ±1 µA

) V 1.8 pF

IND

) (I = +2 mA) VI 0.2 0.4 V

OL

) VI 28 MSPS

S

AP
AP

DD

DD

D

I=VDD

90% V

DD

V10ps
V2ns

IV 3.0 3.3 3.6 V

DD

DD

V

TEST LEVEL CODES

All electrical characteristics are subject to the
following conditions: All parameters having min/
max specifications are guaranteed. The Test
Level column indicates the specific device test­ing actually performed during production and
Quality Assurance inspection. Any blank sec­tion in the data column indicates that the speci­fication is not tested at the specified condition.

SPT

TEST LEVEL

I

II

III
IV

V

VI

3 8/1/00

TEST PROCEDURE

100% production tested at the specified temperature.
100% production tested at TA = +25 °C, and sample

tested at the specified temperatures.
QA sample tested only at the specified temperatures.
Parameter is guaranteed (but not tested) by design

and characterization data.
Parameter is a typical value for information purposes

only.
100% production tested at TA = +25 °C. Parameter is

guaranteed over specified temperature range.

SPT7936