20MHz Bandwidth, Low Noise High Precision Op‐amps

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Rev. A

PHASE REVERSAL

The TP230x op amps are designed to be immune to phase reversal when the input pins exceed the supply voltages,

therefore providing further in-system stability and predictability. Figure 2 shows the input voltage exceeding the supply

voltage without any phase reversal.

Figure 2. No Phase Reversal

EMI SUSCEPTIBILITY AND INPUT FILTERING

Operational amplifiers vary in susceptibility to electromagnetic interference (EMI). If conducted EMI enters the device,

the dc offset observed at the amplifier output may shift from the nominal value while EMI is present. This shift is a result

of signal rectification associated with the internal semiconductor junctions. While all operational amplifier pin functions

can be affected by EMI, the input pins are likely to be the most susceptible. The TP2301 operational amplifier family

incorporates an internal input low-pass filter that reduces the amplifier response to EMI. Both common-mode and

differential mode filtering are provided by the input filter. The filter is designed for a cutoff frequency of approximately

400 MHz (–3 dB), with a roll-off of 20 dB per decade.

Figure 3. TP2301 EMIRR IN+ vs Frequency

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Frequency(MHz)