HI5667 Просмотр технического описания (PDF) - Intersil

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HI5667

8-Bit, 60MSPS A/D Converter with Internal Voltage Reference

Intersil 

HI5667

dynamic performance of the A/D. The sine wave input to the

part is typically -0.5dB down from full scale for all these tests.

SNR and SINAD are quoted in dB. The distortion numbers are

quoted in dBc (decibels with respect to carrier) and DO NOT

include any correction factors for normalizing to full scale.

The Effective Number of Bits (ENOB) is calculated from the

SINAD data by:

ENOB = (SINAD - 1.76 + VCORR) / 6.02,

where: VCORR = 0.5 dB (Typical).

VCORR adjusts the SINAD, and hence the ENOB, for the

amount the analog input signal is backed off from full scale.

Signal To Noise and Distortion Ratio (SINAD)

SINAD is the ratio of the measured RMS signal to RMS sum

of all the other spectral components below the Nyquist

frequency, fS/2, excluding DC.

Signal To Noise Ratio (SNR)

SNR is the ratio of the measured RMS signal to RMS noise at

a specified input and sampling frequency. The noise is the

RMS sum of all of the spectral components below fS/2

excluding the fundamental, the first five harmonics and DC.

Total Harmonic Distortion (THD)

THD is the ratio of the RMS sum of the first 5 harmonic

components to the RMS value of the fundamental input

signal.

2nd and 3rd Harmonic Distortion

This is the ratio of the RMS value of the applicable harmonic

component to the RMS value of the fundamental input signal.

Spurious Free Dynamic Range (SFDR)

SFDR is the ratio of the fundamental RMS amplitude to the

RMS amplitude of the next largest spectral component in the

spectrum below fS/2.

Intermodulation Distortion (IMD)

Nonlinearities in the signal path will tend to generate

intermodulation products when two tones, f1 and f2, are

present at the inputs. The ratio of the measured signal to

the distortion terms is calculated. The terms included in the

calculation are (f1+f2), (f1-f2), (2f1), (2f2), (2f1+f2), (2f1-f2),

(f1+2f2), (f1-2f2). The ADC is tested with each tone 6dB

below full scale.

Transient Response

Transient response is measured by providing a full-scale

transition to the analog input of the ADC and measuring the

number of cycles it takes for the output code to settle within

8-Bit accuracy.

Over-Voltage Recovery

Over-Voltage Recovery is measured by providing a full-scale

transition to the analog input of the ADC which overdrives

the input by 200mV, and measuring the number of cycles it

takes for the output code to settle within 8-Bit accuracy.

Full Power Input Bandwidth (FPBW)

Full power input bandwidth is the analog input frequency at

which the amplitude of the digitally reconstructed output has

decreased 3dB below the amplitude of the input sine wave.

The input sine wave has an amplitude which swings from

-FS to +FS. The bandwidth given is measured at the

specified sampling frequency.

Video Definitions

Differential Gain and Differential Phase are two commonly

found video specifications for characterizing the distortion of a

chrominance signal as it is offset through the input voltage

range of an ADC.

Differential Gain (DG)

Differential Gain is the peak difference in chrominance

amplitude (in percent) relative to the reference burst.

Differential Phase (DP)

Differential Phase is the peak difference in chrominance

phase (in degrees) relative to the reference burst.

Timing Definitions

Refer to Figure 1 and Figure 2 for these definitions.

Aperture Delay (tAP)

Aperture delay is the time delay between the external

sample command (the falling 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 (tAJ)

Aperture jitter is the RMS variation in the aperture delay due

to variation of internal clock path delays.

Data Hold Time (tH)

Data hold time is the time to where the previous data (N - 1)

is no longer valid.

Data Output Delay Time (tOD)

Data output delay time is the time from the rising edge of the

external sample clock to where the new data (N) is valid.

Data Latency (tLAT)

After the analog sample is taken, the digital data

representing an analog input sample is output to the digital

data bus on the 7th cycle of the clock after the analog

sample is taken. This is due to the pipeline nature of the

converter where the analog sample has to ripple through the

internal subconverter stages. This delay is specified as the

data latency. After the data latency time, the digital data

representing each succeeding analog sample is output

during the following clock cycle. The digital data lags the

analog input sample by 7 sample clock cycles.

Power-Up Initialization

This time is defined as the maximum number of clock cycles

that are required to initialize the converter at power-up. The

requirement arises from the need to initialize the dynamic

circuits within the converter.

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