AD73322LAST datasheet(13/49 Pages) AD

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AD73322L

Rev. A | Page 12 of 48

TERMINOLOGY

Absolute Gain

A measure of converter gain for a known signal. Absolute gain

is measured (differentially) with a 1 kHz sine wave at 0 dBm0

for the DAC and with a 1 kHz sine wave at 0 dBm0 for the

ADC. The absolute gain specification is used for gain tracking

error specification.

Crosstalk

Crosstalk is due to coupling of signals from a given channel to

an adjacent channel. It is defined as the ratio of the amplitude

of the coupled signal to the amplitude of the input signal.

Crosstalk is expressed in dB.

Gain Tracking Error

Measures changes in converter output for different signal levels

relative to an absolute signal level. The absolute signal level is

0 dBm0 (equal to absolute gain) at 1 kHz for the DAC and 0

dBm0 (equal to absolute gain) at 1 kHz for the ADC. Gain

tracking error at 0 dBm0 (ADC) and 0 dBm0 (DAC) is 0 dB

by definition.

Group Delay

The derivative of radian phase with respect to radian frequency,

dø(f)/df. Group delay is a measure of the average delay of a

system as a function of frequency. A linear system with a

constant group delay has a linear phase response. The deviation

of group delay from a constant indicates the degree of nonlinear

phase response of the system.

Idle Channel Noise

The total signal energy measured at the output of the device

when the input is grounded (measured in the frequency range

300 Hz to 3400 Hz).

Intermodulation Distortion

With inputs consisting of sine waves at two frequencies, fa and

fb, any active device with nonlinearities creates distortion

products at sum and difference frequencies of mfa ± nfb where

m, n = 0, 1, 2, 3, etc. Intermodulation terms are those for which

neither m nor n is equal to zero. For final testing, the second-

order terms include (fa + fb) and (fa − fb), while the third-order

terms include (2fa + fb), (2fa − fb), (fa + 2fb) and (fa − 2fb).

Power Supply Rejection

Measures the susceptibility of a device to noise on the power

supply. Power supply rejection is measured by modulating the

power supply with a sine wave and measuring the noise at the

output (relative to 0 dB).

Sample Rate

The rate at which the ADC updates its output register and the

DAC updates its output from its input register. The sample rate

can be chosen from a list of four that are fixed relative to the

DMCLK. Sample rate is set by programming bits DIR0-1 in

Control Register B of each channel.

SNR + THD

Signal-to-noise ratio plus harmonic distortion is the ratio of the

rms value of the measured input signal to the rms sum of all

other spectral components in the frequency range 300 Hz to

3400 Hz, including harmonics but excluding dc.

ABBREVIATIONS

Table 7.

Abbreviation

Definition

ADC

Analog-to-digital converter.

AFE

Analog front end.

AGT

Analog gain tap.

ALB

Analog loop-back.

Bandwidth.

CRx

A control register where x is a placeholder for

an alphabetic character (A to H). There are eight

read/write control registers on the AD73322L—

CRA through CRH.

CRx:n

A bit position, where n is a placeholder for a

numeric character (0 to 7), within a control

alphabetic character (A to E). Position 7

represents the MSB and Position 0 represents

the LSB.

DAC

Digital-to-analog converter.

DGT

Digital gain tap.

DLB

Digital loop-back.

DMCLK

Device (internal) master clock. This is the

internal master clock resulting from the

external master clock (MCLK) being divided by

the on-chip master clock divider.

Full scale.

FSLB

Frame sync loop-back—where the SDOFS of

the final device in a cascade is connected to the

RFS and TFS of the DSP and the SDIFS of first

device in the cascade. Data input and output

occur simultaneously. In the case of nonFSLB,

SDOFS and SDO are connected to the Rx port of

the DSP while SDIFS and SDI are connected to

the Tx port.

PGA

Programmable gain amplifier.

Switched capacitor.

SLB

SPORT loop-back.

SNR

Signal-to-noise ratio.

SPORT

Serial port.

THD

Total harmonic distortion.

VBW

Voice bandwidth.

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