16-bit, 2.5 Gsps DAC with 74dB spurious-free dynamic range

September 09, 2014 // By Graham Prophet
LTC2000 is a 16-bit 2.5 Gsample/sec DAC with very high spectral purity of 74 dBc SFDR at 200 MHz output, and better than 68 dBc SFDR for output frequencies from DC to 1 GHz, a 12 dB improvement over alternative 14-bit DACs.

The LTC2000 has low phase noise and a wide 2.1 GHz, -3 dB-point output bandwidth, enabling broadband or high frequency RF synthesis in applications such as high-end instrumentation, broadband communications, test equipment, cable TV DOCSIS CMTS, and radar. Linear Technology comments that in such applications, the DAC is usually the bottleneck in meeting demanding specifications, and that the LTC2000 relieves those pressures by offering a new level of spurious [generation] performance, over 1GHz bandwidth, very high linearity, and excellent accuracy.

The ±1V compliant outputs feature a 40 mA full scale current which can be adjusted as low as 10 mA or as high as 60 mA to suit the application. Data is transferred to the LTC2000 over a parallel LVDS interface port with transfer rates of up to 1.25 Gsample/sec using a 625 MHz double data rate (DDR) data clock. Dual DDR ports are required to achieve the 2.5 Gsample/sec update rate, while a single port can be used to operate at a lower 1.25 Gsample/sec update rate. At 2.5Gsample/sec , the LTC2000 consumes 2.2W from dual 1.8V and 3.3V supplies, while at 1.25 Gsample/sec the device consumes 1.3W. The DAC has an internal pattern generator, LVDS loop out mux, and junction temperature sensing to simplify system development and debug.