HI5714(1998) 데이터 시트보기 (PDF) - Intersil

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HI5714
(Rev.:1998)

8-Bit, 40/60/75/80 MSPS A/D Converter

Intersil 

HI5714

Timing Definitions

Dynamic Performance Definitions

Aperture Delay: Aperture delay is the time delay between

the external sample command (the rising edge of the clock)

and the time at which the signal is actually sampled. This

delay is due to internal clock path propagation delays.

Aperture Jitter: This is the RMS variation in the aperture

delay due to variation of internal clock path delays.

Data Latency

After the analog sample is taken, the data on the bus is out-

put at the next rising edge of the clock. This is due to the out-

put latch of the converter. This delay is specified as the data

latency. After the data latency time, the data representing

each succeeding sample is output at the following clock

pulse. The digital data lags the analog input by 1 cycle.

Static Performance Definitions

Offset Error and Full-Scale Error use a measured value of

the external voltage reference to determine the ideal plus

and minus full-scale values. The results are all displayed in

LSBs.

Bottom Offset Voltage (VOB)

The first code transition should occur at a level 0.5 LSB

above the negative full-scale. Bottom offset voltage is

defined as the deviation of the actual code transition from

this point.

Top Offset Voltage (VOT)

The last code transition should occur for a analog input that

is 1.5 LSBs below positive full-scale. Top Offset Voltage is

defined as the deviation of the actual code transition from

this point.

Differential Linearity Error (DNL)

DNL is the worst case deviation of a code width from the

ideal value of 1 LSB. The converter is guaranteed to have no

missing codes.

Integral Linearity Error (INL)

INL is the worst case deviation of a code center from a best

fit straight line calculated from the measured data.

Fast Fourier Transform (FFT) techniques are used to evalu-

ate the dynamic performance of the HI5714. A low distortion

sine wave is applied to the input, it is sampled, and the out-

put is stored in RAM. The data is then transformed into the

frequency domain with a 2048 point FFT and analyzed to

evaluate the dynamic performance of the A/D. The sine wave

input to the part is 0.5dB down from full scale for these tests.

The distortion numbers are quoted in dBc (decibels with

respect to carrier) and DO NOT include any correction fac-

tors for normalizing to full scale.

Signal-to-Noise Ratio (SNR)

SNR is the measured RMS signal to RMS noise at a speci-

fied input and sampling frequency. The noise is the RMS

sum of all of the spectral components except the fundamen-

tal and the first five harmonics.

Signal-to-Noise + Distortion Ratio (SINAD)

SINAD is the measured RMS signal to RMS sum of all other

spectral components below the Nyquist frequency excluding

DC.

Effective Number Of Bits (ENOB)

The effective number of bits (ENOB) is derived from the

SINAD data. ENOB is calculated from:

ENOB = (SINAD - 1.76) / 6.02

2nd and 3rd Harmonic Distortion

This is the ratio of the RMS value of the 2nd and 3rd

harmonic component respectively to the RMS value of the

measured input signal.

Full Power Input Bandwidth

Full power bandwidth is the frequency at which the ampli-

tude of the digitally reconstructed output has decreased 3dB

below the amplitude of the input sine wave. The input sine

wave has a peak-to-peak amplitude equal to the difference

between the top reference voltage input and the bottom ref-

erence voltage input. The bandwidth given is measured at

the specified sampling frequency.

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