AD73322
–12–
REV. B
TERMINOLOGY
Absolute Gain
Absolute gain is 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
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
Group Delay is defined as the derivative of radian phase with
respect to radian frequency, dø(f)/df. Group delay is a measure
of 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
Idle channel noise is defined as the total signal energy measured
at the output of the device when the input is grounded (mea-
sured in the frequency range 300 Hz–3400 Hz).
Intermodulation Distortion
With inputs consisting of sine waves at two frequencies, fa and
fb, any active device with nonlinearities will create 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
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 sample rate is 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 total harmonic distortion is defined to
be 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–3400 Hz, including harmonics but excluding dc.
ABBREVIATIONS
ADC Analog-to-Digital Converter.
AFE Analog Front End.
AGT Analog Gain Tap.
ALB Analog Loop-Back.
BW Bandwidth.
CRx A Control Register where x is a placeholder for an
alphabetic character (A–E). There are five read/
write control registers on the AD73322—desig-
nated CRA through CRE.
CRx:n A bit position, where n is a placeholder for a nu-
meric character (0–7), within a control register,
where x is a placeholder for an alphabetic charac-
ter (A–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 inter-
nal master clock resulting from the external master
clock (MCLK) being divided by the on-chip mas-
ter clock divider.
FS 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 out-
put occur simultaneously. In the case of Non-
FSLB, 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.
SC Switched Capacitor.
SLB Sport Loop-Back
SNR Signal-to-Noise Ratio.
SPORT Serial Port.
THD Total Harmonic Distortion.
VBW Voice Bandwidth.
