AD1380KD Analog Devices Inc, AD1380KD Datasheet - Page 11

• Manufacturer Part Number: AD1380KD
• Description: A/D Converter (A-D) IC
• Manufacturer: Analog Devices Inc

Specifications of AD1380KD

• No. Of Bits: 16 Bit
• Mounting Type: Through Hole
• Features: Low Cost, 16?Bit Sampling ADC
• No. Of Channels: 1
• Interface Type: Serial, Parallel
• Package / Case: 32-CDIP
• Rohs Status: RoHS non-compliant
• Number Of Bits: 16
• Sampling Rate (per Second): 50k
• Data Interface: Parallel
• Number Of Converters: 1
• Power Dissipation (max): 900mW
• Voltage Supply Source: Dual ±
• Operating Temperature: 0°C ~ 70°C

APPLICATIONS
High performance sampling analog-to-digital converters like
the AD1380 require dynamic characterization to ensure that
they meet or exceed their desired performance parameters for
signal processing applications. Key dynamic parameters include
signal-to-noise ratio (SNR) and total harmonic distortion
(THD), which are characterized using Fast Fourier Transform
(FFT) analysis techniques.
The results of that characterization are shown in Figure 11. In
the test, a 13.2 kHz sine wave is applied as the analog input (f
at a level of 10 dB below full scale; the AD1380 is operated at a
word rate of 50 kHz (its maximum sampling frequency). The
results of a 1024-point FFT demonstrate the exceptional
performance of the converter, particularly in terms of low noise
and harmonic distortion.
In Figure 11, the vertical scale is based on a full-scale input
referenced as 0 dB. In this way, all (frequency) energy cells can be
calculated with respect to full-scale rms inputs. The resulting
signal-to-noise ratio is 83.2 dB, which corresponds to a noise floor
of −93.2 dB. Total harmonic distortion is calculated by adding the
rms energy of the first four harmonics and equals –97.5 dB.
Figure 12. FFT of 13.2 kHz Input Signal at −0.4 dB with a 50 kHz Sample Rate
Figure 11. FFT of 13.2 kHz Input Signal at −10 dB with a 50 kHz Sample Rate
–100
–110
–120
–100
–110
–120
–10
–20
–30
–40
–50
–60
–70
–80
–90
–10
–20
–30
–40
–50
–60
–70
–80
–90
0
0
1
1
44
44
86
86
129 171 214 257 299 342 384 427 469 512
129 171 214 257 299 342 384 427 469 512
FREQUENCY (×48.8281Hz)
FREQUENCY (×48.8281Hz)
FUNDAMENTAL = 13232
SAMPLE RATE = 50000
SIGNAL
NOISE
THD
FUNDAMENTAL = 13232
SAMPLE RATE = 50000
SIGNAL
NOISE
THD
2f (dB) = –100.9
3f (dB) = –101.8
4f (dB) = –111.9
2f (dB) = –80.7
3f (dB) = –99.9
4f (dB) = –102.9
(dB) = –10.0
(dB) = –93.2
(dB) = –97.5
(dB) = –0.4
(dB) = –91.0
(dB) = –80.6
Rev. D | Page 11 of 12
O
)
Increasing the input signal amplitude to –0.4 dB of full scale
causes THD to increase to –80.6 dB as shown in Figure 12.
At lower input frequencies, however, THD performance is
improved. Figure 13 shows a full-scale (−0.3 dB) input signal at
1.41 kHz. THD is now −96.0 dB.
The ultimate noise floor can be seen with low level input signals
of any frequency. In Figure 14, the noise floor is at −94 dB, as
demonstrated with an input signal of 24 kHz at −39.8 dB.
Figure 14. FFT of 24 kHz Input Signal at −39.8 dB with a 50 kHz Sample Rate
Figure 13. FFT of 1.4 kHz Input Signal at −0.3 dB with a 50 kHz Sample Rate
–100
–110
–120
–100
–110
–120
–10
–20
–30
–40
–50
–60
–70
–80
–90
–10
–20
–30
–40
–50
–60
–70
–80
–90
0
0
1
1
44
44
86
86
129 171 214 257 299 342 384 427 469 512
129 171 214 257 299 342 384 427 469 512
FREQUENCY (
FREQUENCY (
20V SPAN
20V SPAN
×
×
48.8281Hz)
48.8281Hz)
FUNDAMENTAL = 1416
SAMPLE RATE = 50000
SIGNAL
NOISE
THD
FUNDAMENTAL = 23975
SAMPLE RATE = 50000
SIGNAL
NOISE
THD
2f (dB) = –97.8
3f (dB) = –102.8
4f (dB) = –106.9
2f (dB) = –116.0
3f (dB) = –113.6
4f (dB) = –112.4
(dB) = –0.3
(dB) = –91.9
(dB) = –96.0
(dB) = –39.8
(dB) = –94.3
(dB) = –107.9
AD1380