input/output data rate
Selectable 2×/4×/8× interpolating filter
Programmable channel gain and offset adjustment
/4, fS/8 digital quadrature modulation capability
f
S
Direct IF transmission mode for 70 MHz + IFs
Enables image rejection architecture
Fully compatible SPI® port
Excellent AC performance
SFDR −69 dBc @ 2 MHz to 35 MHz
WCDMA ACPR −69 dB @ IF = 19.2 MHz
Internal PLL clock multiplier
Selectable internal clock divider
Versatile clock input
Differential/single-ended sine wave or
TTL/CMOS/LVPECL compatible
Versatile input data interface
Twos complement/straight binary data coding
Dual-port or single-port interleaved input data
Single 3.3 V supply operation
Power dissipation: typical 1.2 W @ 3.3 V
On-chip 1.2 V reference
80-lead thermally enhanced TQFP package
AD9773
APPLICATIONS
Communications
Analog quadrature modulation architecture
3G, multicarrier GSM, TDMA, CDMA systems
Broadband wireless, point-to-point microwave radios
Instrumentation/ATE
GENERAL DESCRIPTION
The AD97731 is the 12-bit member of the AD977x pin
compatible, high performance, programmable
2×/4×/8× interpolating TxDAC+ family. The AD977x family
features a serial port interface (SPI) that provides a high level of
programmability, thus allowing for enhanced system-level
options. These options include selectable 2×/4×/8×
interpolation filters; f
modulation with image rejection; a direct IF mode;
programmable channel gain and offset control; programmable
internal clock divider; straight binary or twos complement data
interface; and a single-port or dual-port data interface.
1
Protected by U.S. Patent Numbers 5,568,145; 5,689,257; and 5,703,519. Other
patents pending.
/2, fS/4, or fS/8 digital quadrature
S
(continued on Page 4)
FUNCTIONAL BLOCK DIAGRAM
AD9773
HALFBAND
FILTER1*
DATA
ASSEMBLER
12
I AND Q
NONINTERLEAVED
OR INTERLEAVED
DATA
12
WRITE
SELECT
Rev. B
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.
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.
The selectable 2×/4×/8× interpolation filters simplify the
requirements of the reconstruction filters while simultaneously
enhancing the TxDAC+ family’s pass-band noise/distortion
performance. The independent channel gain and offset adjust
registers allow the user to calibrate LO feedthrough and
sideband suppression errors associated with analog quadrature
modulators. The 6 dB of gain adjustment range can also be used
to control the output power level of each DAC.
The AD9773 features the ability to perform f
digital modulation and image rejection when combined with an
analog quadrature modulator. In this mode, the AD9773 accepts
I and Q complex data (representing a single or multicarrier
waveform), generates a quadrature modulated IF signal along
with its orthogonal representation via its dual DACs, and
presents these two reconstructed orthogonal IF carriers to an
analog quadrature modulator to complete the image rejection
upconversion process. Another digital modulation mode (i.e.,
the direct IF mode) allows the original baseband signal
representation to be frequency translated such that pairs of
images fall at multiples of one-half the DAC update rate.
The AD977x family includes a flexible clock interface accepting
differential or single-ended sine wave or digital logic inputs. An
internal PLL clock multiplier is included and generates the
necessary on-chip high frequency clocks. It can also be disabled
to allow the use of a higher performance external clock source.
An internal programmable divider simplifies clock generation
in the converter when using an external clock source. A flexible
data input interface allows for straight binary or twos
complement formats and supports single-port interleaved or
dual-port data.
Dual high performance DAC outputs provide a differential
current output programmable over a 2 mA to 20 mA range. The
AD9773 is manufactured on an advanced 0.35 micron CMOS
process, operates from a single supply of 3.1 V to 3.5 V, and
consumes 1.2 W of power.
Targeted at a wide dynamic range, multicarrier, and
multistandard systems, the superb baseband performance of the
AD9773 is ideal for wide band CDMA, multicarrier CDMA,
multicarrier TDMA, multicarrier GSM, and high performance
systems employing high order QAM modulation schemes. The
image rejection feature simplifies and can help to reduce the
number of signal band filters needed in a transmit signal chain.
The direct IF mode helps to eliminate a costly mixer stage for a
variety of communications systems.
/2, fS/4, and fS/8
S
PRODUCT HIGHLIGHTS
1. The AD9773 is the 12-bit member of the AD977x pin
compatible, high performance, programmable 2×/4×/8×
interpolating TxDAC+ family.
2. Direct IF transmission is possible for 70 MHz + IFs
through a novel digital mixing process.
/2, fS/4, and fS/8 digital quadrature modulation and user
4. A 2×/4×/8× user selectable interpolating filter eases data
rate and output signal reconstruction filter requirements.
5. User selectable twos complement/straight binary
data coding.
6. User programmable channel gain control over 1 dB range
in 0.01 dB increments.
7. User programmable channel offset control ±10% over
the FSR.
8. Ultrahigh speed 400 MSPS DAC conversion rate.
9. Internal clock divider provides data rate clock for
easy interfacing.
10. Flexible clock input with single-ended or differential input,
CMOS, or 1 V p-p LO sine wave input capability.
11. Low power: Complete CMOS DAC operates on 1.2 W from
a 3.1 V to 3.5 V single supply. The 20 mA full-scale current
can be reduced for lower power operation, and several
sleep functions reduce power during idle periods.
12. On-chip voltage reference: The AD9773 includes a 1.20 V
temperature compensated band gap voltage reference.
13. 80-lead thermally enhanced TQFP.
Rev. B | Page 4 of 60
AD9773
SPECIFICATIONS
T
to T
MIN
Table 1. DC Specifications
Parameter Min Typ Max Unit
RESOLUTION 12 Bits
DC Accuracy1
ANALOG OUTPUT (for IR and 2R Gain Setting Modes)
Offset Error −0.02 ± 0.01 +0.02 % of FSR
Gain Error (With Internal Reference) −1.0 +1.0 % of FSR
Gain Matching −1.0 ± 0.1 +1.0 % of FSR
Full-Scale Output Current2 2 20 mA
Output Compliance Range −1.0 +1.25 V
Output Resistance 200 kΩ
Output Capacitance 3 pF
Gain, Offset Cal DACs, Monotonicity Guaranteed
REFERENCE OUTPUT
Reference Voltage 1.14 1.20 1.26 V
Reference Output Current3 100 nA
REFERENCE INPUT
Input Compliance Range 0.1 1.25 V
Reference Input Resistance 7 kΩ
Small Signal Bandwidth 0.5 MHz
TEMPERATURE COEFFICIENTS
Offset Drift 0 ppm of FSR/°C
Gain Drift (With Internal Reference) 50 ppm of FSR/°C
Reference Voltage Drift ±50 ppm/°C
POWER SUPPLY
AVDD
CLKVDD
CLKVDD (PLL ON)
DVDD
P
DIS
P
DIS
Power Supply Rejection Ratio—AVDD ±0.4 % of FSR/V
OPERATING RANGE −40 +85 °C
1
Measured at I
2
Nominal full-scale current, I
3
Use an external amplifier to drive any external load.
Maximum DAC Output Update Rate (f
Output Settling Time (tST) (to 0.025%) 11 ns
Output Rise Time (10% to 90%)1 0.8 ns
Output Fall Time (10% to 90%)1 0.8 ns
Output Noise (I
AVDD, DVDD, CLKVDD AGND, DGND, CLKGND −0.3 +4.0 V
AVDD, DVDD, CLKVDD AVDD, DVDD, CLKVDD −4.0 +4.0 V
AGND, DGND, CLKGND AGND, DGND, CLKGND −0.3 +0.3 V
REFIO, FSADJ1/FSADJ2 AGND −0.3 AVDD + 0.3 V
I
, I
OUTA
P1B11 to P1B0, P2B11 to P2B0 DGND −0.3 DVDD + 0.3 V
DATACLK, PLL_LOCK DGND −0.3 DVDD + 0.3 V
CLK+, CLK–, RESET CLKGND −0.3 CLKVDD + 0.3 V
LPF CLKGND −0.3 CLKVDD + 0.3 V
SPI_CSB, SPI_CLK, SPI_SDIO, SPI_SDO DGND −0.3 DVDD + 0.3 V
Junction Temperature 125 °C
Storage Temperature −65 +150 °C
Lead Temperature (10 sec) 300 °C
AGND −1.0 AVDD + 0.3 V
OUTB
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
sections of this specification is not implied. Exposure to
THERMAL CHARACTERISTICS
Thermal Resistance
80-Lead Thermally Enhanced TQFP Package
= 23.5°C/W (with thermal pad soldered to PCB)
θ
JA
absolute maximum ratings for extended periods may affect
device reliability.
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.
58 REFIO Reference Output, 1.2 V Nominal.
59 FSADJ2 Full-Scale Current Adjust, Q Channel.
60 FSADJ1 Full-Scale Current Adjust, I Channel.
61, 63, 65,
AVDD Analog Supply Voltage.
76, 78, 80
62, 64, 66,
AGND Analog Common.
67, 70, 71,
74, 75, 77,
79
68, 69 I
72, 73 I
OUTB2
OUTB1
, I
Differential DAC Current Outputs, Q Channel.
OUTA2
, I
Differential DAC Current Outputs, I Channel.
OUTA1
With the PLL enabled, this pin indicates the state of the PLL. A read of a Logic 1 indicates the
PLL is in the locked state. Logic 0 indicates the PLL has not achieved lock. This pin may also be
programmed to act as either an input or output (Address 02h, Bit 3) DATACLK signal running
at the input data rate.
In one-port mode, IQSEL = 1 followed by a rising edge of the differential input clock will latch
the data into the I channel input register. IQSEL = 0 will latch the data into the Q channel
input register. In two-port mode, this pin becomes the Port 2 MSB.
With the PLL disabled and the AD9773 in one-port mode, this pin becomes a clock output
that runs at twice the input data rate of the I and Q channels. This allows the AD9773 to
accept and demux interleaved I and Q data to the I and Q input registers.
In the case where SDIO is an input, SDO acts as an output. When SDIO becomes an output,
SDO enters a High-Z state. This pin can also be used as an output for the data rate clock. For
more information, see the Two-Port Data Input Mode section.
Bidirectional Data Pin. Data direction is controlled by Bit 7 of Register Address 00h. The
default setting for this bit is 0, which sets SDIO as an input.
Data input to the SPI port is registered on the rising edge of SPI_CLK. Data output on the SPI
port is registered on the falling edge.
Chip Select/SPI Data Synchronization. On momentary logic high, resets SPI port logic and
initializes instruction cycle.
Logic 1 resets all of the SPI port registers, including Address 00h, to their default values. A
software reset can also be done by writing a Logic 1 to SPI Register 00h, Bit 5. However, the
software reset has no effect on the bits in Address 00h.
Rev. B | Page 11 of 60
AD9773
TERMINOLOGY
Adjacent Channel Power Ratio (ACPR)
A ratio, in dBc, between the measured power within a channel
relative to its adjacent channel.
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.
Offset Error
The deviation of the output current from the ideal of 0 is called
offset error. For I
are all 0s. For I
, 0 mA output is expected when the inputs
OUTA
, 0 mA output is expected when all inputs are
OUTB
set to 1.s
Output Compliance Range
The range of allowable voltage at the output of a current output
DAC. Operation beyond the maximum compliance limits may
cause either output stage saturation or breakdown, resulting in
nonlinear performance.
Complex Modulation
The process of passing the real and imaginary components of a
jωt
signal through a complex modulator (transfer function = e
=
cosωt + jsinωt) and realizing real and imaginary components
on the modulator output.
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.
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.
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-s.
Group Delay
Number of input clocks between an impulse applied at the
device input and the 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.
Interpolation Filter
If the digital inputs to the DAC are sampled at a multiple rate of
(interpolation rate), a digital filter can be constructed with
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
Linearity Error (Also Called 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 0 to full scale.
Monotonicity
A DAC is monotonic if the output either increases or remains
constant as the digital input increases.
Pass Band
Frequency band in which any input applied therein passes
unattenuated to the DAC output.
Power Supply Rejection
The maximum change in the full-scale output as the supplies
are varied from minimum to maximum specified voltages.
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.
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.
Spurious-Free Dynamic Range
The difference, in dB, between the rms amplitude of the output
signal and the peak spurious signal over the specified
bandwidth.
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.
Temperature Drift
It is specified as the maximum change from the ambient (25°C)
value to the value at either T
MIN
or T
. For offset and gain
MAX
drift, the drift is reported in ppm of full-scale range (FSR) per
°C. For reference drift, the drift is reported in ppm per °C.
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 (dB).