4:1

100

Ω

100

Ω

RLOAD

50

Ω

AGND

IOUT2

IOUT1

1:1

50

Ω

50

Ω

RLOAD

50

Ω

100

Ω

AGND

IOUT2

IOUT1

DAC5652-EP

www.ti.com

SGLS341C – JUNE 2006 – REVISED APRIL 2013

The single-ended configuration may be considered for applications requiring a unipolar output voltage.

Connecting a resistor from either one of the outputs to ground converts the output current into a ground-

referenced voltage signal. To improve on the dc linearity by maintaining a virtual ground, an I-to-V or operational

amplifier configuration may be considered.

Differential With Transformer

Using an RF transformer provides a convenient way of converting the differential output signal into a single-

ended signal while achieving excellent dynamic performance. The appropriate transformer must be carefully

selected based on the output frequency spectrum and impedance requirements.

The differential transformer configuration has the benefit of significantly reducing common-mode signals, thus

improving the dynamic performance over a wide range of frequencies. Furthermore, by selecting a suitable

impedance ratio (winding ratio), the transformer can provide optimum impedance matching while controlling the

compliance voltage for the converter outputs.

Figure 19 and Figure 20 show 50

Ω doubly-terminated transformer configurations with 1:1 and 4:1 impedance

ratios, respectively. Note that the center tap of the primary input of the transformer has to be grounded to enable

a dc-current flow. Applying a 20 mA full-scale output current leads to a 0.5 VPP output for a 1:1 transformer and a

1 VPP output for a 4:1 transformer. In general, the 1:1 transformer configuration has slightly better output

distortion, but the 4:1 transformer has 6 dB higher output power.

Figure 19. Driving a Doubly Terminated 50

Ω Cable Using a 1:1 Impedance Ratio Transformer

Figure 20. Driving a Doubly Terminated 50

Ω Cable Using a 4:1 Impedance Ratio Transformer

Copyright © 2006–2013, Texas Instruments Incorporated

Submit Documentation Feedback

19

Product Folder Links: DAC5652-EP