描述 Description

The DAC5675 is a 14-bit resolution high-speed digital-to-analog converter. The DAC5675 is designed for high-speed digital data transmission in wired and wireless communication systems, high-frequency direct-digital synthesis (DDS), and waveform reconstruction in test and measurement applications. The DAC5675 has excellent spurious free dynamic range (SFDR) at high intermediate frequencies, which makes the DAC5675 well suited for multicarrier transmission in TDMA and CDMA based cellular base transceiver stations BTS.

The DAC5675 operates from a single-supply voltage of 3.3 V. Power dissipation is 820 mW at fclk = 400 MSPS, fout = 70 MHz. The DAC5675 provides a nominal full-scale differential current output of 20 mA, supporting both single-ended and differential applications. The output current can be directly fed to the load with no additional external output buffer required. The output is referred to the analog supply voltage AVDD.

The DAC5675 is manufactured on Texas Instruments advanced high-speed mixed-signal BiCMOS process.

The DAC5675 comprises a LVDS (low-voltage differential signaling) interface. LVDS features a low differential voltage swing with a low constant power consumption across frequency, allowing for high speed data transmission with low noise levels, i.e., low electromagnetic interference (EMI). LVDS is typically implemented in low-voltage digital CMOS processes, making it the ideal technology for high-speed interfacing between the DAC5675 and high-speed low-voltage CMOS ASICs or FPGAs. The DAC5675 current-source-array architecture supports update rates of up to 400 MSPS. On-chip edge-triggered input latches provide for minimum setup and hold times thereby relaxing interface timing.

The DAC5675 has been specifically designed for a differential transformer coupled output with a 50- doubly terminated load. With the 20-mA full-scale output current, both a 4:1 impedance ratio (resulting in an output power of 4 dBm) and 1:1 impedance ratio transformer (?2 dBm) is supported. The last configuration is preferred for optimum performance at high output frequencies and update rates. The output voltage compliance ranges from 2.15 V to AVDD + 0.03 V.

An accurate on-chip 1.2-V temperature compensated bandgap reference and control amplifier allows the user to adjust this output current from 20 mA down to 2 mA. This provides 20-dB gain range control capabilities. Alternatively, an external reference voltage may be applied. The DAC5675 features a SLEEP mode, which reduces the standby power to approximately 150 mW.

The DAC5675 is available in a 48-pin HTQPP thermally enhanced PowerPad package. This package increases thermal efficiency in a standard size IC package. The device is characterized for operation over the industrial temperature range of ?40°C to 85°C.

特性 Features

? 400-MSPS Update Rate
? LVDS-Compatible Input Interface
? Spurious Free Dynamic Range (SFDR) to Nyquist
? 69 dBc at 70-MHz IF, 400 MSPS

? W-CDMA Adjacent Channel Power Ratio ACPR
? 73 dBc at 30.72-MHz IF, 122.88 MSPS
? 71 dBc at 61.44-MHz IF, 245.76 MSPS

? Differential Scalable Current Outputs: 2 mA to 20 mA
? On-Chip 1.2-V Reference
? Single 3.3-V Supply Operation
? Power Dissipation: 820 at fclk = 400 MSPS, fout = 70 MHz
? Package: 48-Pin HTQFP PowerPad?, TJA = 28.8°C/W
? APPLICATIONS
? Cellular Base Transceiver Station Transmit Channel
? CDMA: WCDMA, CDMA2000, IS–95
? TDMA: GSM, IS–136, EDGE/GPRS
? Supports Single-Carrier and Multicarrier Applications

? Test and Measurement: Arbitrary Waveform Generation
? Direct Digital Synthesis (DDS)
? Cable Modem Headend

PowerPAD is a trademark of Texas Instruments. All other trademarks are the property of their respective owners.