12ビット、RF サンプリング A/D コンバータ (ADC)" />
JAJSGI4B November 2018 – March 2021 ADC12DJ3200QML-SP
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The analog inputs of the ADC12DJ3200QML-SP have internal buffers to enable high input bandwidth and to isolate sampling capacitor glitch noise from the input circuit. Analog inputs must be driven differentially because operation with a single-ended signal results in degraded performance. Both AC-coupling and DC-coupling of the analog inputs is supported. The analog inputs are designed for an input common-mode voltage (VCMI) of 0 V, which is terminated internally through single-ended, 50-Ω resistors to ground (GND) on each input pin. DC-coupled input signals must have a common-mode voltage that meets the device input common-mode requirements specified as VCMI in the Recommended Operating Conditions table. The 0-V input common-mode voltage simplifies the interface to split-supply, fully-differential amplifiers and to a variety of transformers and baluns. The ADC12DJ3200QML-SP includes internal analog input protection to protect the ADC inputs during overranged input conditions; see the Analog Input Protection section. Figure 7-2 shows a simplified analog input model.
There is minimal degradation in analog input bandwidth when using single-channel mode versus dual-channel mode. In single-channel mode, INA± is strongly recommended to be used as the input to the ADC because ADC performance is optimized for INA±. However, either analog input (INA+ and INA– or INB+ and INB–) can be used. Using INB± results in degraded performance unless custom trim routines are used to optimize performance for INB± in each device. The desired input can be chosen using SINGLE_INPUT in the input mux control register.
INA± is strongly recommended to be used as the input to the ADC in single-channel mode for optimized performance.