Single- or dual-channel signal processing
Selectable image rejection Hilbert transform
Flexible calibration engine
Direct IF transmission features
Serial control interface
Versatile clock and data interface
3.3 V-compatible digital interface
On-chip 1.2 V reference
80-lead, thermally enhanced, TQFP_EP package
APPLICATIONS
Base stations: multicarrier WCDMA, GSM/EDGE, TD-SCDMA,
IS136, TETRA
Instrumentation
RF signal generators, arbitrary waveform generators
HDTV transmitters
Broadband wireless systems
Digital radio links
Satellite systems
/8 modulation modes
DAC
FUNCTIONAL BLOCK DIAGRAM
AD9786
PRODUCT HIGHLIGHTS
1. 16-bit, high speed, interpolating TxDAC+.
2. 2×/4×/8× user-selectable interpolating filter. The filter
eases data rate and output signal reconstruction filter
requirements.
3. 200 MSPS input data rate.
4. Ultra high speed, 500 MSPS DAC conversion rate.
5. Flexible clock with single-ended or differential input.
CMOS, 1 V p-p sine wave, and LVPECL capability.
6. Complete CMOS DAC function. It operates from a 3.1 V
to 3.5 V single analog (AVDD) supply, 2.5 V digital supply,
and a 3.3 V digital (DRVDD) supply. The DAC full-scale
current can be reduced for lower power operation, and
a sleep mode is provided for low power idle periods.
7. On-chip voltage reference. The AD9786 includes a
1.20 V temperature-compensated band gap voltage
reference.
8. Multichip synchronization. Multiple AD9786 DACs can
be synchronized to a single master AD9786 to ease timing
design requirements and optimize image reject transmit
performance.
LATCH
P1B[15:0]
P2B[15:0]
DATACLK
CLK+
CLK–
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 other
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 Ordering Guide...........................................................60
7/04—Revision 0: Initial Version
Rev. B | Page 3 of 56
AD9786
GENERAL DESCRIPTION
The AD9786 is a 16-bit, high speed, CMOS DAC with
2×/4×/8× interpolation and signal processing features tuned
for communications applications. It offers state-of-the-art
distortion and noise performance. The AD9786 was developed
to meet the demanding performance requirements of multicarrier
and third-generation base stations. The selectable interpolation
filters simplify interfacing to a variety of input data rates while
also taking advantage of oversampling performance gains. The
modulation modes allow convenient bandwidth placement and
selectable sideband suppression.
The flexible clock interface accepts a variety of input types such
as 1 V p-p sine wave, CMOS, and LVPECL in single-ended or
differential mode. Internal dividers generate the required data
rate interface clocks.
The AD9786 provides a differential current output, supporting
single-ended or differential applications; it provides a nominal
full-scale current from 10 mA to 20 mA. The AD9786 is
manufactured on an advanced, low cost, 0.25 μm CMOS process.
Logic 1 Voltage 1.6 V
Logic 0 Voltage 0 0.9 V
Logic 1 Current –10 +10 μA
Logic 0 Current –10 +10 μA
Input Capacitance 5 pF
CLOCK INPUTS1
Input Voltage Range 0 2.65 V
Common-Mode Voltage 0.75 1.5 2.25 V
Differential Voltage 0.5 1.5 V
Latch Pulse Width (t
) 5 ns
LPW
Data Setup Time to DACCLK Out in Master Mode (tS) −0.5 ns
Data Hold Time to DACCLK Out in Master Mode (tH) 2.9 ns
1
See the Clock/Data Timing section for setup and hold times in various timing modes.
= 20 mA, unless otherwise noted.
OUTFS
Rev. B | Page 7 of 56
AD9786
ABSOLUTE MAXIMUM RATINGS
Table 4.
Parameter With Respect to Rating
AVDD1, AVDD2,
DRVDD
AGND1, AGND2,
ACGND, ADGND,
−0.3 V to +3.6 V
CLKGND, DGND
ACVDD, ADVDD,
CLKVDD, DVDD
AGND1, AGND2,
ACGND, ADGND,
−0.3 V to +2.8 V
CLKGND, DGND
AGND1, AGND2,
ACGND, ADGND,
CLKGND, DGND
AGND1, AGND2,
ACGND, ADGND,
CLKGND, DGND
−0.3 V to +0.3 V
REFIO, FSADJ AGND1 −0.3 to AVDD1 + 0.3
IOUTA, IOUTB AGND1 −1.0 to AVDD1 +0.3
P1B15 to P1B0,
DGND −0.3 to DRVDD + 0.3
P2B15 to P2B0, RESET
DATACLK DGND −0.3 to DRVDD + 0.3
CLK+, CLK− CLKGND −0.3 to CLKVDD + 0.3
CSB, SCLK,
DGND −0.3 to DRVDD + 0.3
SDIO, SDO
Junction
−65°C to +125°C
Temperature Range
Storage
150°C
Temperature
Lead Temperature
300°C
(10 sec)
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 RESISTANCE
θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.
Table 5. Thermal Resistance
Package Type1 θ
80-lead TQFP_EP (Thermally Enhanced) 23.5 °C/W
`
1
With thermal pad soldered to PCB.
Unit
JA
ESD CAUTION
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 this product
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.
5, 6 CLK+, CLK– I Differential Clock Input.
2 DNC Do Not Connect.
31 DATACLK I/O
1, 3 CLKVDD Clock Domain 2.5 V.
4, 7 CLKGND Clock Domain 0 V.
DCLKEXT
0x02[3]
0
Mode
Pin configured for input of channel data rate or synchronizer clock. Internal clock
synchronizer can be turned on or off with DCLKCRC (0x02[2]).
1 Pin configured for output of channel data rate or synchronizer clock.
ONEPORTCLOCK/P2B14
03152-002
Rev. B | Page 9 of 56
AD9786
ANALOG
Table 7. Analog Pin Function Descriptions
Pin No. Mnemonic Direction Description
59 REFIO A Reference.
60 FSADJ A Full-Scale Adjust.
70, 71 IOUTB, IOUTA A Differential DAC Output Currents.
61 DNC Do Not Connect.
62, 79 ADVDD Analog Domain Digital Content 2.5 V.
63, 78 ADGND Analog Domain Digital Content 0 V.
64, 77 ACVDD Analog Domain Clock Content 2.5 V.
65, 76 ACGND Analog Domain Clock Content 0 V.
66, 75 AVDD2 Analog Domain Clock Switching 3.3 V.
67, 74 AGND2 Analog Domain Switching 0 V.
68, 73 AVDD1 Analog Domain Quiet 3.3 V.
69, 72 AGND1 Analog Domain Quiet 0 V.
80 DNC Do Not Connect.
DATA
Table 8. Data Pin Function Descriptions
Pin No. Mnemonic Direction Description
10 to 15, 18 to
24, 27 to 29
32 IQSEL/P2B15 I
33 ONEPORTCLOCK/P2B14 I/O
34, 37 to 43,
46 to 51
30 DRVDD Digital Output Pin Supply, 3.3 V.
9, 17, 26,
36, 44, 52
8, 16, 25,
35, 45, 53
P1B15 to P1B0 I
P2B13 to P2B0 I Input Data Port 2, Bit 13 to Bit 0.
DVDD Digital Domain, 2.5 V.
DGND Digital Domain, 0 V.
Input Data Port 1.
ONEPORT
0x02[6] Mode
0 Latched data routed for I channel processing.
1
ONEPORT
0x02[6]
0 X X
1 0 0
1 0 1
1 1 0
1 1 1
ONEPORT
0x02[6]
0 Latched data routed for Q channel Bit 14 processing.
1
Latched data demultiplexed by IQSEL and routed for
interleaved I/Q processing.
IQPOL
0x02[1]
Pin configured for output of clock at twice the channel
data route.
IQSEL/
P2B15 Mode (IQPOL = 0)
Latched data routed to Q channel Bit 15
(MSB) processing.
Latched data on Data Port 1 routed to Q
channel processing.
Latched data on Data Port 1 routed to I
channel processing.
Latched data on Data Port 1 routed to I
channel processing.
Latched data on Data Port 1 routed to Q
channel processing.
Rev. B | Page 10 of 56
AD9786
SERIAL INTERFACE
Table 9. Serial Interface Pin Function Descriptions
Pin No. Mnemonic Direction Description
54 SDO O
55 SDIO I/O
56 SCLK I Serial Interface Clock.
57 CSB I Serial Interface Chip Select.
58 RESET I Resets entire chip to default state.
SDIODIR
0x00[7]
CSB
1 X High impedance.
0 0 Serial data output.
0 1 High impedance.
SDIODIR
CSB
0x00[7] Mode
1 X High impedance.
0 0 Serial data output.
0 1 Serial data input/output depending on Bit 7 of the serial instruction byte.
Mode
Rev. B | Page 11 of 56
AD9786
TERMINOLOGY
Linearity Error (Integral Nonlinearity or INL)
Linearity error is defined as the maximum deviation of the
actual analog output from the ideal output, determined by a
straight line drawn from zero to full scale.
Settling Time
The time required for the output to reach and remain within a
specified error band about its final value, measured from the
start of the output transition.
Differential Nonlinearity (DNL)
DNL is the measure of the variation in analog value, normalized to full scale, associated with a 1 LSB change in digital
input code.
Monotonicity
A D/A converter is monotonic if the output either increases or
remains constant as the digital input increases.
Offset Error
The deviation of the output current from the ideal of zero is
called offset error. For I
inputs are all 0s. For I
, 0 mA output is expected when the
OUTA
, 0 mA output is expected when all
OUTB
inputs are set to 1.
Gain Error
The difference between the actual and ideal output span. The
actual span is determined by the output when all inputs are set
to 1, minus the output when all inputs are set to 0.
Output Compliance Range
The range of allowable voltage at the output of a current-output
DAC. Operation beyond the maximum compliance limits can
cause either output stage saturation or breakdown, resulting in
nonlinear performance.
Tem p er at u re Dr if t
Temperature drift is specified as the maximum change from the
ambient (+25°C) value to the value at either T
MIN
or T
MAX
. For
offset and gain drift, the drift is reported in ppm of full-scale
range (FSR) per degree Celsius. For reference drift, the drift is
reported in ppm per degree Celsius.
Power Supply Rejection
The maximum change in the full-scale output as the supplies
are varied from minimum to maximum specified voltages.
Glitch Impulse
Asymmetrical switching times in a DAC give rise to undesired
output transients that are quantified by a glitch impulse. It is
specified as the net area of the glitch in pV-sec.
Spurious-Free Dynamic Range (SFDR)
The difference between the rms amplitude of the output signal
and the amplitude of the peak spurious signal over the specified
bandwidth. The units are often in dBc (dB with respect to the
carrier).
Total Harmonic Distortion (THD)
THD is the ratio of the rms sum of the first six harmonic
components to the rms value of the measured fundamental. It is
expressed as a percentage or in decibels.
Signal-to-Noise Ratio (SNR)
SNR is the ratio of the rms value of the measured output signal
to the rms sum of all other spectral components below the
Nyquist frequency, excluding the first six harmonics and dc.
The value for SNR is expressed in decibels.
Interpolation Filter
If the digital inputs to the DAC are sampled at a multiple rate of
(interpolation rate), a digital filter can be constructed that has
f
DATA
a sharp transition band near f
appear around f
(output data rate) can be greatly suppressed.
DAC
/2. Images that would typically
DATA
Pass Band
Frequency band in which any input applied therein passes
unattenuated to the DAC output.
Stop-Band Rejection
The amount of attenuation of a frequency outside the pass band
applied to the DAC, relative to a full-scale signal applied at the
DAC input within the pass band.
Rev. B | Page 12 of 56
AD9786
Group Delay
Number of input clocks between an impulse applied at the
device input and peak DAC output current. A half-band FIR
filter has constant group delay over its entire frequency range
Impulse Response
Response of the device to an impulse applied to the input.
Hilbert Transform
A function with unity gain over all frequencies, but with a phase
shift of 90° for negative frequencies and a phase shift of –90° for
positive frequencies. Although this function cannot be implemented ideally, it can be approximated with a short FIR filter
with enough accuracy to be very useful in single sideband radio
architectures.
Adjacent Channel Leakage Ratio (ACLR)
A ratio in dBc between the measured power within a channel
relative to its adjacent channel.
Complex Modulation
The process of passing the real and imaginary components of a
signal through a complex modulator (transfer function = e
coswt + jsinwt) and realizing real and imaginary components
on the modulator output.
jwt
=
Complex Image Rejection
In a traditional two-part upconversion, two images are created
around the second IF frequency. These images are redundant
and have the effect of wasting transmitter power and system
bandwidth. By placing the real part of a second complex modulator
in series with the first complex modulator, either the upper or
lower frequency image near the second IF can be rejected.