AD6640

Manufacturer Part NumberAD6640
DescriptionMulti-Channel, Multi-Mode Receiver Chipset
ManufacturerAnalog Devices
AD6640 datasheet
 


Specifications of AD6640

Resolution (bits)12bit# Chan1
Sample Rate65MSPSInterfacePar
Analog Input TypeDiff-UniAin Range2 V p-p
Adc ArchitecturePipelinedPkg TypeQFP
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FEATURES
65 MSPS Minimum Sample Rate
80 dB Spurious-Free Dynamic Range
IF Sampling to 70 MHz
710 mW Power Dissipation
Single 5 V Supply
On-Chip T/H and Reference
Twos Complement Output Format
3.3 V or 5 V CMOS Compatible Output Levels
APPLICATIONS
Cellular/PCS Base Stations
Multichannel, Multimode Receivers
GPS Anti-Jamming Receivers
Communications Receivers
Phased Array Receivers
GENERAL DESCRIPTION
The AD6640 is a high speed, high performance, low power,
monolithic 12-bit analog-to-digital converter. All necessary
functions, including track-and-hold (T/H) and reference, are
included on-chip to provide a complete conversion solution.
The AD6640 runs on a single 5 V supply and provides CMOS
compatible digital outputs at 65 MSPS.
Specifically designed to address the needs of multichannel,
multimode receivers, the AD6640 maintains 80 dB spurious-
free dynamic range (SFDR) over a bandwidth of 25 MHz.
Noise performance is also exceptional: typical signal-to-noise
ratio is 68 dB.
The AD6640 is built on Analog Devices’ high speed complemen-
tary bipolar process (XFCB) and uses an innovative multipass
architecture. Units are packaged in a 44-lead plastic quad flatpack
(LQFP) specified from –40°C to +85°C.
REV. A
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective companies.
12-Bit, 65 MSPS
IF Sampling A/D Converter
FUNCTIONAL BLOCK DIAGRAM
AV
DV
CC
CC
AIN
TH1
TH2
BUF
AIN
2.4V
ADC
DAC
V
REF
REFERENCE
6
ENCODE
INTERNAL
DIGITAL ERROR CORRECTION LOGIC
TIMING
ENCODE
MSB
D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
GND
PRODUCT HIGHLIGHTS
1. Guaranteed sample rate is 65 MSPS.
2. Fully differential analog input stage specified for frequencies
up to 70 MHz; enables IF sampling.
3. Low power dissipation: 710 mW off a single 5 V supply.
4. Digital outputs may be run on 3.3 V supply for easy interface
to digital ASICs.
5. Complete solution: reference and track-and-hold.
6. Packaged in small, surface-mount 44-lead plastic LQFP.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
Fax: 781/326-8703
© 2003 Analog Devices, Inc. All rights reserved.
AD6640
A
TH3
ADC
7
AD6640
LSB
www.analog.com

AD6640 Summary of contents

  • Page 1

    ... All necessary functions, including track-and-hold (T/H) and reference, are included on-chip to provide a complete conversion solution. The AD6640 runs on a single 5 V supply and provides CMOS compatible digital outputs at 65 MSPS. Specifically designed to address the needs of multichannel, multimode receivers, the AD6640 maintains 80 dB spurious- free dynamic range (SFDR) over a bandwidth of 25 MHz ...

  • Page 2

    ... V) CC Output Coding NOTES Best dynamic performance is obtained by driving ENCODE and ENCODE differentially. See Encoding the AD6640 section for more details. Performance versus ENCODE/ENCODE 1 power is shown in TPC 12. 2 For dc-coupled applications, the ENCODE input common-mode range specifies the common-mode range the ENCODE inputs can tolerate when driven differentially by the minimum differential input voltage of 0 ...

  • Page 3

    ... V –3– AD6640 = – +85 C, MIN MAX AD6640AST Min Typ Max Unit 65 MSPS 6.5 MSPS 400 ps 0.3 ps rms 6.5 ns 6.5 ns 8.5 10.5 12 – +85 C, MIN MAX AD6640AST Min Typ Max Unit 67 63.5 67.2 dB 67 dBc 74 80 dBc 79.5 dBc 78.5 dBc 85 ...

  • Page 4

    ... ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the AD6640 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality ...

  • Page 5

    ... Function 3.3 V/5 V Power Supply (Digital). Powers output stage only. Encode Input. Data conversion initiated on rising edge. Complement of ENCODE. Drive differentially with ENCODE or bypass to ground for single-ended clock mode. See Encoding the AD6640 section. Ground Analog Input Complement of Analog Input Internal Voltage Reference. Nominally 2.4 V. Bypass to ground with 0.1 µ ...

  • Page 6

    ... AD6640 DEFINITION OF SPECIFICATIONS Analog Bandwidth (Small Signal) The analog input frequency at which the spectral power of the fundamental frequency (as determined by the FFT analysis) is reduced by 3 dB. Aperture Delay The delay between a differential crossing of ENCODE and ENCODE and the instant at which the analog input is sampled. ...

  • Page 7

    ... INPUTS AIN (ENCODE) N – 2 (D11–D0 Figure 1. Timing Diagram T/H V REF T 17k ENCODE –7– –7– Equivalent Circuits–AD6640 N – CURRENT MIRROR REF D0–D11 CURRENT MIRROR Figure 5. Digital Output Stage 2.4V V REF 0.5mA ...

  • Page 8

    ... AD6640 –Typical Performance Characteristics 0 ENCODE = 65MSPS AIN = 2.2MHz 100 120 dc 6.5 13.0 19.5 FREQUENCY – MHz TPC 1. Single Tone at 2.2 MHz 100 120 dc 6.5 13.0 19.5 FREQUENCY – MHz TPC 2. Single Tone at 15.5 MHz 0 ENCODE = 65MSPS AIN = 31.0MHz ...

  • Page 9

    ... TPC 11. SNR, Worst Spurious vs. Duty Cycle –20 –10 0 –15 TPC 12. SNR, Worst Spurious vs. ENCODE Power –9– AD6640 AIN = 19.5MHz WORST SPUR SNR SAMPLE RATE – MSPS ENCODE = 65MSPS AIN = 2.2MHz WORST SPUR SNR 30 35 ...

  • Page 10

    ... AD6640 0 ENCODE = 65MSPS AIN = 19.5MHz @ –36dBFS –20 NO DITHER –40 –60 –80 –100 –120 dc 6.5 13.0 19.5 FREQUENCY – MHz TPC 13. 16K FFT without Dither 100 90 ENCODE = 65MSPS 80 AIN = 19.5MHz NO DITHER SFDR = 80dB 10 REFERENCE LINE 0 –80 –70 –60 –50 –40 –30 ANALOG INPUT POWER LEVEL – dBFS TPC 14 ...

  • Page 11

    ... The result is a 12-bit parallel digital CMOS compatible word, coded as twos complement. APPLYING THE AD6640 Encoding the AD6640 A valid ENCODE clock must be present on the AD6640 before the application V). Best performance is obtained by CC driving the ENCODE pins differentially. However, the AD6640 is also designed to interface with TTL and CMOS logic families ...

  • Page 12

    ... Therefore, the analog source driving the AD6640 should be ac-coupled to the input pins. Since the differential input impedance of the AD6640 is 0.9 kΩ, the analog input power requirement is only –3 dBm, simplifying the drive amplifier in many cases ...

  • Page 13

    ... AD6640 (see Driving the Analog Input section). The onboard termination resistor is 270 Ω. This resistor, in parallel with the AD6640’s input resistance (900 Ω), provides a 50 Ω load to the analog source driving the 1:4 transformer different input impedance is required, replace R16 by using the equation where Z is desired input impedance (200 Ω ...

  • Page 14

    ... Data is latched in a pipeline configuration; a rising edge generates the new AD6640 data sample, latches the previous data at the con- verter output, and strobes the external data register over J3. Note that power and ground must be applied power the digital logic section of the evaluation board ...

  • Page 15

    ... D4 29 DUT D3 28 AD6640 (LSB GND 348 CONNECT 348 C13 C15 C16 0.1 F 0.1 F 0.1 F Figure 18. AD6640ST/PCB Schematic –15– AD6640 74LCX574 ( 348 348 348 348 ...

  • Page 16

    ... AD6640 Figure 19. AD6640ST/PCB Top Side Silkscreen Figure 20. AD6640ST/PCB Bottom Side Silkscreen NOTE: Evaluation boards are often updated; consult factory for latest version. Figure 21. AD6640ST/PCB Top Side Copper Figure 22. AD6640ST/PCB Bottom Side Copper (Positive) –16– REV. A ...

  • Page 17

    ... Figure 23. AD6640ST/PCB Ground Layer (Negative) REV. A Figure 24. AD6640ST/PCB “Split” Power Layer (Negative) –17– AD6640 ...

  • Page 18

    ... System Requirements Figure 28 shows a typical wideband receiver subsystem based around the AD6640. This strip consists of a wideband IF filter, amplifier, ADC, latches, channelizer, and interface to a digital signal processor. This design shows a typical clocking scheme used in many receiver designs ...

  • Page 19

    ... CLOCK band-pass filter will remove harmonics generated within the amplifier, but intermods should be better than the performance of the A/D converter. In the case of the AD6640, amplifier intermods must be better than –80 dBFS when driving full- scale power. As mentioned earlier, there are several amplifiers to choose from and the specifications depend on the end application ...

  • Page 20

    ... For example kHz AMPS signal is being digitized with an AD6640 sampling at 65 MSPS, the ratio would be 0.015 MHz/32.5 MHz. Expressed in log form, the processing gain is –10 × log (0.015 MHz/32.5 MHz) or 33.4 dB. ...

  • Page 21

    ... IF Sampling Using the AD6640 as a Mix-Down Stage Since performance of the AD6640 extends beyond the baseband region into the third Nyquist zone, the converter has many uses as a mix-down converter in both narrow-band and wideband applications. This application is called band-pass sampling. Doing – ...

  • Page 22

    ... RECEIVE CHAIN FOR A PHASED-ARRAY CELLULAR BASE STATION The AD6640 is an excellent digitizer for beam forming in phased- array antenna systems. The price performance of the AD6640 and AD6620 channelizers allows for a very competitive solution. Phased-array base stations allow better coverage by focusing the receivers’ ...

  • Page 23

    ... ANTENNA 1 AD6640 COMMON LO ANTENNA 2 AD6640 ANTENNA 3 AD6640 ANTENNA 4 AD6640 ANTENNA 5 AD6640 ANTENNA 6 AD6640 ANTENNA 7 AD6640 ANTENNA 8 AD6640 Figure 34. Receive Chain for a Phased-Array Cellular Base Station with Eight Antennas and 32 Channels REV. A SYNC 1 AD6620 (1) AD6620 (2) AD6620 (3) AD6620 (30) AD6620 (31) AD6620 (32) AD6620s (32 CHANNELS) SYNC 1 ...

  • Page 24

    ... Sheet changed from REV REV. A. Updated Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Universal Changed to 44-Lead Plastic Quad Flatpack (LQFP Universal Changes to ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Updated TPCs 13 and Text inserted in Encoding the AD6640 section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Updated OUTLINE DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 OUTLINE DIMENSIONS 44-Lead Plastic Quad Flatpack [LQFP] (ST-44) Dimensions shown in millimeters 0 ...