Datasheet

especially at low output frequencies and high signal

amplitudes. It is recommended to connect the trans-

former center tap to ground.

If a transformer is not used, the outputs must have a

resistive termination to ground. Figure 17 shows the

MAX5895 output configured for differential DC-coupled

mode. The DC-coupled configuration can be used to

eliminate waveform distortion due to highpass filter

effects. Applications include communication systems

employing analog quadrature upconverters and requir-

ing a high-speed DAC for baseband I/Q synthesis.

If a single-ended DC-coupled unipolar output is desir-

able, OUTIP (OUTQP) should be selected as the out-

put, and connect OUTIN (OUTQN) to ground. Using the

MAX5895 output single-ended is not recommended

because it introduces additional noise and distortion.

The distortion performance of the DAC also depends

on the load impedance. The MAX5895 is optimized for

a 50Ω double termination. It can be used with a trans-

former output as shown in Figure 16 or just one 25Ω

resistor from each output to ground and one 50Ω resis-

tor between the outputs (Figure 17). Higher output ter-

mination resistors may be used, as long as each output

voltage does not exceed +1V with respect to GND, but

at the cost of degraded distortion performance and

increased output noise voltage.

MAX5895

16-Bit, 500Msps Interpolating and Modulating

Dual DAC with CMOS Inputs

______________________________________________________________________________________ 27

Figure 17. The DC-Coupled Differential Output Configuration

MAX5895

OUTQP

OUTQN

QDAC

25Ω

50Ω

25Ω

OUTIP

OUTIN

IDAC

25Ω

50Ω

25Ω