EVAL-AD7898CB(Rev0) 查看數據表（PDF） - Analog Devices
零件编号
产品描述 (功能)
生产厂家
EVAL-AD7898CB Datasheet PDF : 16 Pages
| |||
Typical Performance Characteristics–AD7898
PERFORMANCE CURVES
TPC 1 shows a typical FFT plot for the AD7898 at 220 kSPS
sampling rate with a 30 kHz input frequency while operating in
Mode 0.
5
–20
8192 POINT FFT
–15
fSAMPLE = 220kSPS
fIN = 30kHz
–30
SINAD = 71.823dB
THD = –90.28dB
–35
SFDR = –91.467dB
–40
–55
–50
–75
–60
–95
–70
–115
0
20
40
60
80
100
FREQUENCY – kHz
TPC 1. Mode 0 Dynamic Performance
TPC 2 shows a typical FFT plot for the AD7898 at 220 kSPS
sampling rate with a 30 kHz input frequency while operating in
Mode 1.
–80
0
10 20 30 40 50 60 70 80
INPUT FREQUENCY – kHz
TPC 3. PSRR vs. Supply Ripple Frequency
TPC 4 shows a graph of effective number of bits versus input
frequency while sampling at 220 kSPS.
5
11.9
8192 POINT FFT
–15
fSAMPLE = 220kSPS
fIN = 30kHz
11.8
SINAD = 71.779dB
THD = –88.337dB
11.7
–35
SFDR = –89.639dB
11.6
–55
11.5
–75
11.4
–95
11.3
–115
0
20
40
60
80
100
FREQUENCY – kHz
TPC 2. Mode 1 Dynamic Performance
TPC 3 shows the Power Supply Rejection Ratio versus supply
frequency for the AD7898. The power supply rejection ratio is
defined as the ratio of the power in the ADC output at full-scale
frequency f, to the power of a 100 mV sine wave applied to the
ADC VDD supply of frequency fS.
PSRR (dB) = 10 log (Pf/Pfs)
Pf = Power at frequency f in ADC output, Pfs = power at fre-
quency fs coupled on to the ADC VDD supply input. Here a
100 mV peak-to-peak sine wave is coupled onto the VDD supply.
100 nF decoupling was used on the supply.
11.2
0
20
40
60
80
100
INPUT FREQUENCY – kHz
TPC 4. Effective Number of Bits vs. Input Frequency at
220 kSPS
The effective number of bits for a device can be calculated from
its measured Signal to (Noise + Distortion) Ratio (see Termi-
nology section). TPC 4 shows a typical plot of effective number
of bits versus frequency for the AD7898 from dc to fSAMPLE/2.
The sampling frequency is 220 kSPS.
The formula for Signal to (Noise + Distortion) Ratio is related
to the resolution or number of bits in the converter. Rewriting
the formula, below, gives a measure of performance expressed in
effective number of bits (N):
N = (SNR – 1.76)/6.02
where SNR is Signal to (Noise + Distortion) Ratio.
REV. 0
–7–
Share Link: 