1629

Applications

Bipolar Applications

To convert the output of the HI5735 to a bipolar 4V swing, the

following applications circuit is recommended. The reference

can only provide 125

µA of drive, so it must be buffered to

create the bipolar offset current needed to generate the -2V

output with all bits “off”. The output current must be converted

to a voltage and then gained up and offset to produce the

proper swing. Care must be taken to compensate for the

voltage swing and error

Definition of Specifications

Integral Linearity Error, INL, is the measure of the worst

case point that deviates from a best fit straight line of data

values along the transfer curve.

Differential Linearity Error, DNL, is the measure of the

error in step size between adjacent codes along the con-

verter’s transfer curve. Ideally, the step size is 1 LSB from

one code to the next, and the deviation from 1 LSB is known

as DNL. A DNL specification of greater than -1 LSB guaran-

tees monotonicity.

Feedthru, is the measure of the undesirable switching noise

coupled to the output.

Output Voltage Full Scale Settling Time, is the time

required from the 50% point on the clock input for a full scale

step to settle within an

Output Voltage Small Scale Settling Time, is the time

required from the 50% point on the clock input for a 100mV

applications reconstructing highly correlated signals such as

sine waves with more than 5 points per cycle.

Glitch Area, GE, is the switching transient appearing on the

output during a code transition. It is measured as the area

under the curve and expressed as a picoVolt•Time

specification (typically pV•s).

Differential Gain,

wave with a normalized amplitude.

Differential Phase,

∆Φ, is the phase error from an ideal

sine wave.

Signal to Noise Ratio, SNR, is the ratio of a fundamental to

the noise floor of the analog output. The first 5 harmonics

used to eliminate alias products.

Total Harmonic Distortion, THD, is the ratio of the DAC

output fundamental to the RMS sum of the harmonics. The

clock frequency is used to eliminate alias products.

Spurious Free Dynamic Range, SFDR, is the amplitude

difference from a fundamental to the largest harmonically or

non-harmonically related spur. A sine wave is loaded into the

eliminate noise from clocking alias terms.

Intermodulation Distortion, IMD, is the measure of the

sum and difference products produced when a two tone

input is driven into the D/A. The distortion products created

will arise at sum and difference frequencies of the two tones.

IMD can be calculated using the following equation:

FIGURE 13. MEASURING GLITCH ENERGY

GLITCH ENERGY = (

HI5735

REF OUT

1/2 CA2904

+

-

+

-

+

-

50

Ω

5k

Ω

1/2 CA2904

5k

Ω

60

Ω

240

Ω

240

Ω

HFA1100

0.1

µF

FIGURE 14. BIPOLAR OUTPUT CONFIGURATION

(21)

(26)

IMD

20Log (RMS of Sum and Difference Distortion Products)

RMS Amplitude of the Fundamental

()

------------------------------------------------------------------------------------------------------------------------------------------------------- .

=

HI5735