VP216

6

Fig.4 System timing diagram

C

Latch

Comparator

L

V ref.

AIN_(Q,I)

Clock to ADC

CLKOUT

Data Out

CLKOUT

Data Outputs

TTL

Threshold

Tpw 1

Tpw 0

AIN_(Q,I)

N

N+1

N-1

N+1

N

N-1

Output

Buffer

Output

Buffer

ELECTRICAL CHARACTERISTICS DEFINITIONS

Analog Bandwidth

The analog input frequency at which the spectral power

of the fundamental frequency, as determined by FFT analysis

is reduced by 3dB.

Aperture Delay

The delay between the rising edge of the 90MHz clock

signal and the instant the analog input signal is sampled.

Aperture Jitter

The sample to sample variation in aperture delay.

Bit Error Rate (BER)

The number of spurious code errors produced for any

given input sinewave frequency at a given clock frequency. In

this case it is the number of codes occurring outside the

histogram cusp for a 1/2 FS sinewave.

Data Outputs, Set-up and Hold Time

Data output timings are measured from 2.4V and 0.4V to

the 1.4V threshold on the rising edge of the output clock.

Differential Non-linearity

The deviation in any code width from an ideal 1 LSB step.

Effective Number of Bits (ENOB)

This is a measure of a device's dynamic performance

and may be obtained from the SNR or from a sine wave

curve test fit according to the following expressions:

ENOB = SNR-1.76/6.02

or

ENOB = N-log2[rms error (actual)/rms error (ideal)]

where N is the conversion resolution and the actual rms error

is the deviation from an ideal sine wave, calculated from the

converter outputs with a sine wave input.

Integral Non-linearity (INL)

The deviation of the centre of each code from a

reference line which has been determined by a least squares

curve fit.

Signal-to-Noise Ratio (SNR)

The ratio of the rms signal amplitude to the rms value of

‘noise’ which is defined as the sum of all other spectral

components, including the harmonics, but excluding D.C.

with a full-scale analog input signal.

Th

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