11-bit, 200 MSPS output data rate per channel
Integrated noise shaping requantizer (NSR)
Performance with NSR enabled
SNR: 75.5 dBFS in 40 MHz band to 70 MHz @ 185 MSPS
SNR: 73.7 dBFS in 60 MHz band to 70 MHz @ 185 MSPS
Performance with NSR disabled
SNR: 66.5 dBFS to 70 MHz @ 185 MSPS
SFDR: 83 dBc to 70 MHz @ 185 MSPS
Low power: 1.2 W @ 185 MSPS
1.8 V analog supply operation
1.8 V LVDS (ANSI-644 levels) output
1-to-8 integer clock divider
Internal ADC voltage reference
1.75 V p-p analog input range (programmable to 2.0 V p-p)
Differential analog inputs with 800 MHz bandwidth
95 dB channel isolation/crosstalk
Serial port control
User-configurable built-in self-test (BIST) capability
Energy-saving power-down modes
APPLICATIONS
Communications
Diversity radio and smart antenna (MIMO) systems
Multimode digital receivers (3G)
WCDMA, LTE, CDMA2000
WiMAX, TD-SCDMA
I/Q demodulation systems
General-purpose software radios
AD6657
FUNCTIONAL BLOCK DIAGRAM
GND DRVDD DRGND
AD6657
VIN+A
VIN–A
VCMA
VIN+B
VIN–B
VCMB
VIN+C
VIN–C
VCMC
VIN+D
VIN–D
VCMD
PIPELINE
PIPELINE
PIPELINE
PIPELINE
REFERENCE
SERIAL PORT
SCLK SDIOCSBCLK+
1411
ADC
ADC
ADC
ADC
NOISE SHAPING
1411
NOISE SHAPING
1411
NOISE SHAPING
1411
NOISE SHAPING
REQUANTIZER
REQUANTIZER
REQUANTIZER
REQUANTIZER
AND LVDS DRIVERS
DATA MULTIPLEXER
CLOCK
DIVIDER
CLK–
Figure 1.
PRODUCT HIGHLIGHTS
1. Four ADCs are contained in a small, space-saving,
10 mm × 10 mm × 1.4 mm, 144-ball CSP_BGA package.
2. Pin selectable noise shaping requantizer (NSR) function
that allows for improved SNR within a reduced bandwidth
of up to 60 MHz at 185 MSPS.
3. LVDS digital output interface configured for low cost
FPGA families.
4. 230 mW per ADC core power consumption.
5. Operation from a single 1.8 V supply.
6. Standard serial port interface (SPI) that supports various
product features and functions, such as data formatting
(offset binary or twos complement), NSR, power-down,
test modes, and voltage reference mode.
7. On-chip integer 1-to-8 input clock divider and multichip
sync function to support a wide range of clocking schemes
and multichannel subsystems.
DC0±AB
D0±AB
PORT A
D10±AB
DC0±CD
D0±CD
PORT B
D10±CD
MODE
SYNC
PDWN
08557-001
Rev. B
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
rights of third parties that may result from its use. Specifications subject to change without notice. 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 owners.
Changes to Design Guidelines Section........................................ 30
10/09—Revision 0: Initial Version
Data Sheet AD6657
GENERAL DESCRIPTION
The AD6657 is an 11-bit, 200 MSPS, quad-channel intermediate
frequency (IF) receiver specifically designed to support multiantenna systems in telecommunication applications where high
dynamic range performance, low power, and small size are desired.
The device consists of four high performance analog-to-digital
converters (ADCs) and noise shaping requantizer (NSR) digital
blocks. Each ADC consists of a multistage, differential pipelined
architecture with integrated output error correction logic. The
ADC features a wide bandwidth switched-capacitor sampling
network within the first stage of the differential pipeline. An
integrated voltage reference eases design considerations. A duty
cycle stabilizer (DCS) compensates for variations in the ADC
clock duty cycle, allowing the converters to maintain excellent
performance.
Each ADC output is connected internally to an NSR block. The
integrated NSR circuitry allows for improved SNR performance
in a smaller frequency band within the Nyquist bandwidth. The
device supports two different output modes selectable via the
external MODE pin or the SPI.
With the NSR feature enabled, the outputs of the ADCs are
processed such that the AD6657 supports enhanced SNR
performance within a limited portion of the Nyquist bandwidth
while maintaining an 11-bit output resolution. The NSR block
can be programmed to provide a bandwidth of either 22% or
33% of the sample clock. For example, with a sample clock rate
of 185 MSPS, the AD6657 can achieve up to 75.5 dBFS SNR for
a 40 MHz bandwidth in the 22% mode and up to 73.7 dBFS
SNR for a 60 MHz bandwidth in the 33% mode.
With the NSR block disabled, the ADC data is provided directly to
the output with a resolution of 11 bits. The AD6657 can achieve
up to 66.5 dBFS SNR for the entire Nyquist bandwidth when
operated in this mode. This allows the AD6657 to be used in
telecommunication applications such as a digital predistortion
observation path where wider bandwidths are desired.
After digital signal processing, multiplexed output data is
routed into two 11-bit output ports such that the maximum
data rate is 400 Mbps (DDR). These outputs are set at 1.8 V
LVDS and support ANSI-644 levels.
The AD6657 receiver digitizes a wide spectrum of IF frequencies.
Each receiver is designed for simultaneous reception of a separate
antenna. This IF sampling architecture greatly reduces component cost and complexity compared with traditional analog
techniques or less integrated digital methods.
Flexible power-down options allow significant power savings.
Programming for device setup and control is accomplished
using a 3-wire SPI-compatible serial interface with numerous
modes to support board-level system testing.
The AD6657 is available in a Pb-free/RoHS compliant, 144-ball,
10 mm × 10 mm chip scale package ball grid array (CSP_BGA)
and is specified over the industrial temperature range of −40°C
to +85°C.
Parameter Temperature Min Typ Max Unit
RESOLUTION Full 11 Bits
ACCURACY
No Missing Codes Full Guaranteed
Offset Error Full −4.5 2 7.4 mV
Gain Error Full ±3 ±7 % FSR
Differential Nonlinearity (DNL)1 Full ±0.1 ±0.5 LSB
Integral Nonlinearity (INL)1 Full ±0.2 ±0.5 LSB
MATCHING CHARACTERISTIC
Offset Error Full −2.4 2.5 8.3 mV
Gain Error Full ±1 ±3 % FSR
TEMPERATURE DRIFT
Offset Error Full 2 ppm/°C
Gain Error Full 40 ppm/°C
ANALOG INPUT
Input Range Full 1.4 1.75 2.0 V p-p
Input Common-Mode Voltage Full 0.9 V
Input Resistance (Differential) Full 20 kΩ
Input Capacitance2 Full 5 pF
POWER SUPPLIES
Supply Voltage
AVDD Full 1.7 1.8 1.9 V
DRVDD Full 1.7 1.8 1.9 V
Supply Current
1
I
Full 510 548 mA
AVDD
1
I
(1.8 V LVDS) Full 155 169 mA
DRVDD
POWER CONSUMPTION
Sine Wave Input1 Full 1195 1290 mW
Standby Power3 Full 130 mW
Power-Down Power Full 4.5 18 mW
1
Measured with a 10 MHz, 0 dBFS sine wave, with 100 Ω termination on each LVDS output pair.
2
Input capacitance refers to the effective capacitance between one differential input pin and AGND.
3
Standby power is measured with a dc input and the CLKx pins inactive (set to AVDD or AGND).
Logic Compliance CMOS/LVDS/LVPECL
Internal Common-Mode Bias Full 0.9 V
Differential Input Voltage Full 0.2 3.6 V p-p
Input Voltage Range Full AGND − 0.3 AVDD + 0.2 V
High Level Input Voltage Full 1.2 2.0 V
Low Level Input Voltage Full 0 0.8 V
High Level Input Current Full −10 +10 μA
Low Level Input Current Full −10 +10 μA
Input Resistance Full 8 10 12 kΩ
Input Capacitance Full 4 pF
SYNC INPUT
Logic Compliance CMOS
Internal Bias Full 0.9 V
Input Voltage Range Full AGND AVDD V
High Level Input Voltage Full 1.2 AVDD V
Low Level Input Voltage Full AGND 0.6 V
High Level Input Current Full −100 +100 μA
Low Level Input Current Full −100 +100 μA
Input Resistance Full 12 16 20 kΩ
Input Capacitance Full 1 pF
LOGIC INPUT (CSB)1
High Level Input Voltage Full 1.22 2.1 V
Low Level Input Voltage Full 0 0.6 V
High Level Input Current Full −10 +10 μA
Low Level Input Current Full 40 132 μA
Input Resistance Full 26 kΩ
Input Capacitance Full 2 pF
LOGIC INPUT (SCLK)2
High Level Input Voltage Full 1.22 2.1 V
Low Level Input Voltage Full 0 0.6 V
High Level Input Current Full −92 −135 μA
Low Level Input Current Full −10 +10 μA
Input Resistance Full 26 kΩ
Input Capacitance Full 2 pF
LOGIC INPUT/OUTPUT (SDIO)1
High Level Input Voltage Full 1.22 2.1 V
Low Level Input Voltage Full 0 0.6 V
High Level Input Current Full −10 +10 μA
Low Level Input Current Full 38 128 μA
Input Resistance Full 26 kΩ
Input Capacitance Full 5 pF
tDS Setup time between the data and the rising edge of SCLK 2 ns
tDH Hold time between the data and the rising edge of SCLK 2 ns
t
Period of the SCLK 40 ns
CLK
tS Setup time between CSB and SCLK 2 ns
tH Hold time between CSB and SCLK 2 ns
t
SCLK pulse width high 10 ns
HIGH
t
SCLK pulse width low 10 ns
LOW
t
EN_SDIO
t
DIS_SDIO
Timing Diagrams
VIN
Time required for the SDIO pin to switch from an input to
an output relative to the SCLK falling edge
Time required for the SDIO pin to switch from an output to
an input relative to the SCLK rising edge
N – 1
t
A
N
10 ns
10 ns
N + 4
N + 5
N + 3
CLK–
CLK+
DCO+
DCO–
D10(MSB)+AB
D10(MSB)–AB
D0(LSB)+AB
D0(LSB)–AB
N + 1
t
CH
t
CL
t
DCO
D10AD10B
D0AD0BD0AD0BD0AD0BD0AD0BD0AD0BD0AD0B
D10AD10BD10AD10BD10AD10BD10AD10BD10AD10BD10AD10B
D0AD0B
1/
f
S
t
SKEW
t
PD
N + 2
Figure 2. Data Output Timing (Timing for Channel C and Channel D Is Identical to Timing for Channel A and Channel B)
CLK+
t
HSYNC
08557-003
SYNC
t
SSYNC
Figure 3. SYNC Input Timing Requirements
08557-002
Rev. B | Page 8 of 32
Data Sheet AD6657
ABSOLUTE MAXIMUM RATINGS
Table 6.
Parameter Rating
AVDD to AGND −0.3 V to +2.0 V
DRVDD to AGND −0.3 V to +2.0 V
VIN+x, VIN−x to AGND −0.3 V to AVDD + 0.2 V
CLK+, CLK− to AGND −0.3 V to AVDD + 0.2 V
SYNC to AGND −0.3 V to AVDD + 0.2 V
VCMx to AGND −0.3 V to AVDD + 0.2 V
CSB to AGND −0.3 V to DRVDD + 0.2 V
SCLK to AGND −0.3 V to DRVDD + 0.2 V
SDIO to AGND −0.3 V to DRVDD + 0.2 V
PDWN to AGND −0.3 V to DRVDD + 0.2 V
MODE to AGND −0.3 V to DRVDD + 0.2 V
Digital Outputs to AGND −0.3 V to DRVDD + 0.2 V
DCO+AB, DCO−AB, DCO+CD,
−0.3 V to DRVDD + 0.2 V
DCO−CD to AGND
Operating Temperature Range
−40°C to +85°C
(Ambient)
Maximum Junction Temperature
150°C
Under Bias
Storage Temperature Range
−65°C to +150°C
(Ambient)
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
THERMAL CHARACTERISTICS
The values in Table 7 are per JEDEC JESD51-7 plus JEDEC
JESD25-5 for a 2S2P test board. Typical θ
4-layer PCB with a solid ground plane. As shown in Tabl e 7,
airflow improves heat dissipation, which reduces θ
tion, metal in direct contact with the package leads from metal
traces, through holes, ground, and power planes reduces θ
Table 7.
Airflow
Package Type
144-Ball CSP_BGA,
10 mm × 10 mm
(BC-144-1)
1
Per JEDEC JESD51-2 (still air) or JEDEC JESD51-6 (moving air).
2
Per MIL-STD 883, Method 1012.1.
3
Per JEDEC JESD51-8 (still air).
Velocity θ
0 m/s 26.9 8.9 6.6
1 m/s 24.2
2.5 m/s 23.0
The values in Table 8 are from simulations. The PCB is a JEDEC
multilayer board. Thermal performance for actual applications
requires careful inspection of the conditions in the application
to determine whether they are similar to those assumed in these
calculations.
A7 CLK+ Input ADC Clock Input—True
A6 CLK− Input ADC Clock Input—Complement
C12 VIN+A Input Differential Analog Input Pin (+) for Channel A
D12 VIN−A Input Differential Analog Input Pin (−) for Channel A
D11 VCMA Output Common-Mode Level Bias Output for Analog Input Channel A
A11 VIN+B Input Differential Analog Input Pin (+) for Channel B
A10 VIN−B Input Differential Analog Input Pin (−) for Channel B
B10 VCMB Output Common-Mode Level Bias Output for Analog Input Channel B
A2 VIN+C Input Differential Analog Input Pin (+) for Channel C
A3 VIN−C Input Differential Analog Input Pin (−) for Channel C
B3 VCMC Output Common-Mode Level Bias Output for Analog Input Channel C
C1 VIN+D Input Differential Analog Input Pin (+) for Channel D
D1 VIN−D Input Differential Analog Input Pin (−) for Channel D
D2 VCMD Output Common-Mode Level Bias Output for Analog Input Channel D
K7 D0+AB Output Channel A and Channel B LVDS Output Data 0—True
J7 D0−AB Output Channel A and Channel B LVDS Output Data 0—Complement
5887-004
Rev. B | Page 10 of 32
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