WM2148IFT/V Ver la hoja de datos (PDF) - Wolfson Microelectronics plc
Número de pieza
componentes Descripción
Fabricante
WM2148IFT/V Datasheet PDF : 14 Pages
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Production Data
75
74
73
72
71
70
69
68
67
10
100
1000
Signal Frequency [kHz] at -1dB
Figure 10 Signal to Noise Ratio at 3MSPS
WM2148
10000
75
74
73
72
71
70
69
68
67
10
100
1000
Signal Frequency [kHz] at -1dB
Figure 11 Signal to Noise Ratio at 8MSPS
10000
APPLICATION INFORMATION
DRIVING THE ANALOGUE INPUT
The WM2148 has a fully differential input. This is advantageous for signal to noise ratio, spurious
free dynamic range, and harmonic distortion. It is recommended that the analogue input pins IN+ and
IN- are connected as shown in Figure 12 below.
DIFFERENTIAL
ANALOGUE
INPUT
22 Ohms
100pF
22 Ohms
100pF
IN+
WM2148
IN-
DIGITAL I/O
Figure 12 Recommended Input Configuration
In this configuration, the ADC converts the difference ¨9IN of the two input signals VIN+ and VINí. The
resistors and capacitors on the inputs decouple the driving source output from the ADC and also
serve as first order low pass filters to reduce out of band noise.
The input range on both inputs is 0V to AVDD. The full-scale value is determined by the voltage
reference. The positive full-scale output is reached when ¨9IN equals ¨9REF, and the negative full-
scale output is reached when ¨9IN equals -¨9REF.
¨9IN
-¨9REF
0
¨9REF
OUTPUT
- full scale
0
+ full scale
The digital outputs of the WM2148 are 3V CMOS compatible. In order to avoid current feedback
errors, the capacitive load on these outputs should be as low as possible (maximum 15pF). Adding
100Ω series resistors on the digital outputs cam improve system performance by limiting the current
during output transitions (this reduces noise on the power supplies).
WOLFSON MICROELECTRONICS LTD
PD Rev 1.1 February 2001
11
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