DAC5675A - 14-Bit, 400-MSPS Digital-to-Analog Converter (DAC)

The DAC5675A is a 14-bit resolution high-speed digital-to-analog converter. The DAC5675A 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 DAC5675A has excellent spurious-free dynamic range (SFDR) at high intermediate frequencies, which makes the DAC5675A well-suited for multicarrier transmission in TDMA- and CDMA-based cellular base transceiver stations (BTSs).

The DAC5675A operates from a single-supply voltage of 3.3 V. Power dissipation is 660 mW at f_CLK = 400 MSPS, f_OUT = 70 MHz. The DAC5675A provides a nominal full-scale differential current output of 20mA, 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 AV_DD.

The DAC5675A comprises a low-voltage differential signaling (LVDS) interface for high-speed digital data input. 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; that is, with 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 DAC5675A and high-speed low-voltage CMOS ASICs or FPGAs. The DAC5675A current-sink-array architecture supports update rates of up to 400MSPS. On-chip edge-triggered input latches provide for minimum setup and hold times, thereby relaxing interface timing.

The DAC5675A has been specifically designed for a differential transformer-coupled output with a 50 Ω 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) are supported. The last configuration is preferred for optimum performance at high output frequencies and update rates. The outputs are terminated to AVDD and have voltage compliance ranges from AV_DD –1 to AV_DD + 0.3 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 DAC5675A features a SLEEP mode, which reduces the standby power to approximately 18 mW.

The DAC5675A is available in a 48-pin HTQFP 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.

• 400MSPS Update Rate
• LVDS-Compatible Input Interface
• Spurious-Free Dynamic Range (SFDR) to Nyquist:
  • 69dBc at 70MHz IF, 400MSPS
• W-CDMA Adjacent Channel Power Ratio (ACPR):
  • 73dBc at 30.72MHz IF, 122.88MSPS
  • 71dBc at 61.44MHz IF, 245.76MSPS
• Differential Scalable Current Sink Outputs: 2mA to 20mA
• On-Chip 1.2V Reference
• Single 3.3V Supply Operation
• Power Dissipation: 660mW at f_CLK = 400MSPS, f_OUT = 20MHz
• Package: 48-Pin HTQFP PowerPad,
  T_JA = 28.8°C/W