Common Test Parameters for DAC's                         

   

Test Parameter

Unit

Typical Description

Resolution

Bits

This is the number of bits that the DAC has. If a DAC has n bits, then its output analog signal span can be divided (or "resolved") into 2n states, each corresponding to its own digital input code.  The higher the number of bits, the better is the resolution of a DAC.

Voltage Reference Input Range

V

This indicates the minimum and maximum voltages that may be used as the DAC's external reference voltage.

Example of an Actual Spec: 0V min; Vdd max

Bipolar Zero Error or Midscale Error

mV

This is the deviation of the actual analog output of the DAC from the ideal output of 0V when the 2's complement input code representing half-scale (all zeros) is loaded into the input register.

Example of an Actual Spec: +/- 30 mV typ.

Non-Linearity, Differential (DNL)

LSB or

% of FSR

This is the difference between the actual or measured output change and the ideal output change for a digital input change of 1 LSB, i.e., for a transition between two adjacent codes.

Examples of Actual Specs:

+/- 1 LSB;  +/- 0.001% FSR typ.

Non-Linearity, Integral (INL)

or Relative Accuracy

LSB

This is the maximum deviation of the output from the straight line between the zero and full-scale points, excluding the effects of zero and full-scale errors.

Example of an Actual Spec:

+/-1 LSB typ.; +/- 4 LSB's max.

Analog Output Range or Full-Scale Range

V

This is the difference between the maximum and minimum analog output values that the DAC is specified to provide.

Example of Actual Spec: -3V to +3V, Bipolar Mode

Logic Input Voltage, Vih

(Logic "1")

V

This is the minimum voltage that the digital inputs of the DAC are guaranteed to recognize as a Logic "1".

Example of an Actual Spec: 2.4 V min.

Logic Input Voltage, Vil

(Logic "0")

V

This is the maximum voltage that the digital inputs of the DAC are guaranteed to recognize as a Logic "0".

Example of an Actual Spec: 0.8 V max.

Input Leakage Current, IIL

µA

This is maximum leakage current exhibited by a digital input at logic "0".

Example of an Actual Spec:  2 µA max. for Vil = 0.4 V.

Settling Time

µsec

This is the time required by the outputs of a DAC to reach and remain within a specified error band about its final value. This is measured from the digital input transition.

Examples of Actual Specs:

1.5 µsec typ. for a 6V step;

1.0 µsec typ. for a 1 LSB step;

Analog Positive Power Supply (+Vs)

V

This is the voltage range that can be used for the analog positive supply of the DAC.

Example of an Actual Spec:

+4.75V min.; +5.0V typ.; +13.2V max.

Analog Negative Power Supply (-Vs)

V

This is the voltage range that can be used for the analog negative supply of the DAC.

Example of an Actual Spec:

-13.2V min.; -5V typ.; -4.75V max.

Logic Positive Power Supply (+VL)

V

This is the voltage range that can be used for the logic positive supply of the DAC.

Example of an Actual Spec:

+4.75V min.; +5.0V typ.; +13.2V max.

Logic Negative Power Supply (-VL)

V

This is the voltage range that can be used for the logic negative supply of the DAC.

Example of an Actual Spec:

-13.2V min.; -5V typ.; -4.75V max.

Analog Output Impedance

kW

This is the dynamic load presented by a DAC at its analog output. 

Example of an Actual Spec: 0.1 kW typ.

Gain Error or

Full-Scale Error

mV

or %FSR

This indicates how closely the analog output of a DAC matches its ideal value at full scale and may be expressed in mV or as a % of the FSR. For many DAC's, the ideal maximum output voltage is Vref-1 LSB.

Example of an Actual Spec: +/-1.22 mV

Signal-to-Noise Ratio (SNR)

dB

This is the ratio of the amplitude of the analog output of the DAC when the output is set to full-scale to the amplitude of the output when it is set to zero.

Example of an Actual Spec:

107 dB min.; 110 dB typ. for 20 Hz-30 kHz

Total Harmonic Distortion (THD)

dB

This is the ratio of the rms sum of the first few (2nd to 6th) harmonic components of the DAC output to the DAC output's fundamental value, usually expressed in dB.

Example of an Actual Spec: -80 dB typ.

 

 

   

See Also:  DAC's ADC Parameters Electrical Test

  

HOME

    

Copyright © 2001-2005  EESemi.com. All Rights Reserved.