DAC39RF10 datasheet(94/232 Pages) TI2

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7.3.1.1 NRZ Mode

Non-return-to-zero (NRZ) mode is the standard zero-order hold mode. The timing diagram for NRZ mode is

given in Figure 7-3. The sample is output from the DAC on the CLK rising edge and held until the rising edge.

This output waveform can be thought of as a rectangular filter in time domain resulting in a sinc response in the

frequency domain. The result is a frequency response that has significant power loss in the 2nd and 3rd Nyquist

zones and a null at the sampling rate and is meant for 1st Nyquist zone operation only. A plot of the frequency

response of NRZ mode is shown in Figure 7-4.

CLK+

CLK–

DAC Output

(Sine Wave)

+IFS

-IFS

tpd

TSample = 1/FCLK

Figure 7-3. NRZ Mode Timing Diagram

FOUT/FCLK

0.5

1.5

-50

-40

-30

-20

-10

Figure 7-4. NRZ Mode Output Frequency Response

7.3.1.2 RTZ Mode

Return-to-zero (RTZ) mode is similar to the standard zero-order hold mode used by DACs; however, the

response adds a return-to-zero pulse for the second half of the sample period. The timing diagram for RTZ mode

is given in Figure 7-5. This output waveform can be thought of as a rectangular filter in time domain that is half

the length of that which is used in NRZ mode, resulting in a sinc response that is expanded by two times in the

frequency domain. The result is a frequency response with less power loss in the 2nd Nyquist zone and a null

at twice the sampling rate. It can be used for 1st and 2nd Nyquist zone applications. The return-to-zero pulse

provides flatter response through the first Nyquist zone at a tradeoff of 6dB lower peak power. A plot of the

frequency response of RTZ mode is shown in Figure 7-6.

DAC39RF10-SP, DAC39RF10-SEP

DAC39RFS10-SP, DAC39RFS10-SEP

SBAS932A – MARCH 2024 – REVISED FEBRUARY 2026

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DAC39RF10 Datasheet(PDF) 94 Page - Texas Instruments