1FEATURES

234· 500-MSPS Maximum-Update-Rate DAC

· WCDMA ACPR

– 1 Carrier: 76 dB Centered at 30.72-MHz IF,

245.76 MSPS

– 1 Carrier: 73 dB Centered at 61.44-MHz IF,

245.76 MSPS

– 2 Carrier: 72 dB Centered at 30.72-MHz IF,

245.76 MSPS

– 4 Carrier: 64 dB Centered at 92.16-MHz IF,

491.52 MSPS

· Selectable 2×, 4×, 8×, and 16× Interpolation

– Linear Phase

– 0.05-dB Pass-Band Ripple

– 80-dB Stop-Band Attenuation

– Stop-Band Transition 0.4–0.6 fDATA

· 32-Bit Programmable NCO

· On-Chip 2×–16× PLL Clock Multiplier With

Bypass Mode

· Differential Scalable Current Outputs: 2 mA to

20 mA

· On-Chip 1.2-V Reference

· 1.8-V Digital and 3.3-V Analog Supplies

· 1.8-V/3.3-V CMOS-Compatible Interface

· Power Dissipation: 950 mW at Full Maximum

Operating Conditions

· Package: 100-Pin HTQFP

APPLICATIONS

· Cellular Base Transceiver Station Transmit

Channel

– CDMA: W-CDMA, CDMA2000, IS-95

– TDMA: GSM, IS-136, EDGE/UWC-136

· Baseband I and Q Transmit

· Input Interface: Quadrature Modulation for Interfacing With Baseband Complex Mixing

ASICs

· Single-Sideband Up-Conversion

· Diversity Transmit

· Cable Modem Termination System

DESCRIPTION

The DAC5686 is a dual-channel 16-bit high-speed digital-to-analog converter (DAC) with integrated 2×, 4×, 8×,

and 16× interpolation filters, a numerically controlled oscillator (NCO), onboard clock multiplier, and on-chip

voltage reference. The DAC5686 has been specifically designed to allow for low input data rates between the

DAC and ASIC, or FPGA, and high output transmit intermediate frequencies (IF). Target applications include

high-speed digital data transmission in wired and wireless communication systems and high-frequency

direct-digital synthesis DDS.

The DAC5686 provides three modes of operation: dual-channel, single-sideband, and quadrature modulation. In

dual-channel mode, interpolation filtering increases the DAC update rate, which reduces sinx/x rolloff and

enables the use of relaxed analog post-filtering.

Single-sideband mode provides an alternative interface to the analog quadrature modulators. Channel carrier

selection is performed at baseband by mixing in the ASIC/FPGA. Baseband I and Q from the ASIC/FPGA are

input to the DAC5686, which in turn performs a complex mix resulting in Hilbert transform pairs at the outputs of

the DAC5686's two DACs. An external RF quadrature modulator then performs the final single-sideband

up-conversion. The DAC5686's complex mixing frequencies are flexibly chosen with the 32-bit programmable

NCO.