16-Bit, 30 MSPS a D/A Converter AD768 FUNCTIONAL BLOCK DIAGRAM FEATURES 30 MSPS Update Rate V DCOM DD 16-Bit Resolution (MSB) Linearity: 1/2 LSB DNL 14 Bits AD768 DB15 1 LSB INL 14 Bits MSBs: SEGMENTED CURRENT SOURCES Fast Settling: 25 ns Full-Scale Settling to 0.025% AND SWITCHES SFDR 1 MHz Output: 86 dBc MSB THD 1 MHz Output: 71 dBc DECODER LSBs: IOUTA AND CURRENT SOURCES, Low Glitch Impulse: 35 pV-s EDGE- SWITCHES, AND IOUTB TRIGGERED Power Dissipation: 465 mW 1k R-2R 1k 1k BIT LADDERS On-Chip 2.5 V Reference LATCHES LADCOM Edge-Triggered Latches 2.5V Multiplying Reference Capability BANDGAP CONTROL V EE REFERENCE AMP DB0 APPLICATIONS (LSB) Arbitrary Waveform Generation NR CLOCK NC REFCOM REFOUT IREFIN Communications Waveform Reconstruction Vector Stroke Display PRODUCT DESCRIPTION PRODUCT HIGHLIGHTS The AD768 is a 16-bit, high speed digital-to-analog converter 1. The low glitch and fast settling time provide outstanding (DAC) that offers exceptional ac and dc performance. The dynamic performance for waveform reconstruction or digital AD768 is manufactured on ADIs Advanced Bipolar CMOS synthesis requirements, including communications. (ABCMOS) process, combining the speed of bipolar transistors, 2. The excellent dc accuracy of the AD768 makes it suitable for the accuracy of laser-trimmable thin film resistors, and the effi- high speed A/D conversion applications. ciency of CMOS logic. A segmented current source architecture is combined with a proprietary switching technique to reduce 3. On-chip, edge-triggered input CMOS latches interface glitch energy and maximize dynamic accuracy. Edge triggered readily to CMOS logic families. The AD768 can support up- input latches and a temperature compensated bandgap reference date rates up to 40 MSPS. have been integrated to provide a complete monolithic DAC 4. A temperature compensated, 2.5 V bandgap reference is solution. included on-chip allowing for generation of the reference The AD768 is a current-output DAC with a nominal full-scale input current with the use of a single external resistor. An ex- output current of 20 mA and a 1 k output impedance. Differ- ternal reference may also be used. ential current outputs are provided to support single-ended 5. The current output(s) of the AD768 may be used singly or or differential applications. The current outputs may be tied differentially, either into a load resistor, external op amp directly to an output resistor to provide a voltage output, or fed summing junction or transformer. to the summing junction of a high speed amplifier to provide a 6. Proper selection of an external resistor and compensation buffered voltage output. Also, the differential outputs may be capacitor allow the performance-conscious user to optimize interfaced to a transformer or differential amplifier. the AD768 reference level and bandwidth for the target The on-chip reference and control amplifier are configured for application. maximum accuracy and flexibility. The AD768 can be driven by the on-chip reference or by a variety of external reference volt- ages based on the selection of an external resistor. An external capacitor allows the user to optimally trade off reference band- width and noise performance. The AD768 operates on 5 V supplies, typically consuming 465 mW of power. The AD768 is available in a 28-pin SOIC package and is specified for operation over the industrial tem- perature range. REV. B Information furnished by Analog Devices is believed to be accurate and Analog Devices, Inc., 1996 reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. otherwise under any patent or patent rights of Analog Devices. Tel: 617/329-4700 Fax: 617/326-8703(T to T , V = +5.0 V, V = 5.0 V, LADCOM, REFCOM, DCOM = 0 V, IREFIN = 5 mA, MIN MAX DD EE CLOCK = 10 MHz, unless otherwise noted) AD768SPECIFICATIONS Parameter Min Typ Max Units RESOLUTION 16 Bits 1 DC ACCURACY Linearity Error T = +25C84 +8 LSB A to T 8 +8 LSB T MIN MAX Differential Nonlinearity = +25C62 +6 LSB T A T to T 8 +8 LSB MIN MAX Monotonicity (13-Bit) GUARANTEED OVER RATED SPECIFICATION TEMPERATURE RANGE ANALOG OUTPUT Offset Error 0.2 +0.2 % of FSR Gain Error 1.0 +1.0 % of FSR 2 Full-Scale Output Current 20 mA Output Compliance Range 1.2 +5.0 V Output Resistance 0.8 1.0 1.2 k Output Capacitance 3 pF REFERENCE OUTPUT Reference Voltage 2.475 2.5 2.525 V 3 Reference Output Current +5.0 +15 mA REFERENCE INPUT Reference Input Current 1 5 7 mA 4 Reference Bandwidth Small Signal, IREF = 5 mA 0.1 mA 28 MHz Large Signal, IREF = 4 mA 2 mA 9 MHz TEMPERATURE COEFFICIENTS o Unipolar Offset Drift 5 +5 ppm of FSR/ C 5 o Gain Drift 20 +20 ppm of FSR/ C 6 o Gain Drift 40 +40 ppm of FSR/ C o Reference Voltage Drift 30 +30 ppm/ C 7 DYNAMIC PERFORMANCE Maximum Output Update Rate 30 40 MSPS Output Settling Time (t ) (to 0.025%) 25 35 ns ST Output Propagation Delay (t)10 ns PD Glitch Impulse 35 pV-s Output Rise Time (10% to 90%) 5 ns Output Fall Time (10% to 90%) 5 ns Output Noise (DB0DB15 High, into 50 ) 3 nV/Hz Differential Gain Error 0.01 % Differential Phase Error 0.01 Degree DIGITAL INPUTS Logic 1 Voltage 3.5 V Logic 0 Voltage 1.5 V Logic 1 Current 10 +10 A Logic 0 Current 10 +10 A Input Capacitance 10 pF Input Setup Time (t)10 ns S Input Hold Time (t)5 ns H Latch Pulse Width (t)10 ns LPW 7 AC LINEARITY Spurious-Free Dynamic Range (SFDR Within a Window) F = 1.002 MHz CLOCK = 10 MHz 2 MHz Span 86 79 dB OUT F = 1.002 MHz CLOCK = 20 MHz 2 MHz Span 85 dB OUT F = 5.002 MHz CLOCK = 30 MHz 10 MHz Span 78 dB OUT Spurious-Free Dynamic Range (SFDR to Nyquist) F = 1.002 MHz CLOCK = 10 MHz 74 70 dB OUT F = 1.002 MHz CLOCK = 20 MHz 73 dB OUT F = 5.002 MHz CLOCK = 30 MHz 67 dB OUT Total Harmonic Distortion (THD) F = 1.002 MHz CLOCK = 10 MHz 71 68 dB OUT F = 1.002 MHz CLOCK = 20 MHz 66 dB OUT F = 5.002 MHz CLOCK = 30 MHz 61 dB OUT 2 REV. 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