For no-buffer configuration, there are two others ways to increase the phase margin: (a) by

increasing the amplifier’s gain or (b) by placing a capacitor in parallel with the feedback resistor to

counteract the parasitic capacitance associated with inverting node.

Power-Supply Bypassing and Layout

The FC321SOT family operates from either a single +2.5V to +5.5V supply or dual ±1.25V to ±2.75V

supplies. For single-supply operation, bypass the power supply VDD with a 0.1μF ceramic

capacitor which should be placed close to the VDD pin. For dual-supply operation, both the VDD

and the VSS supplies should be bypassed to ground with separate 0.1μF ceramic capacitors. 2.2μF

tantalum capacitor can be added for better performance.

Figure 3. Amplifier with Bypass Capacitors

TYPICAL APPLICATION CIRCUITS

Differential Amplifier

The circuit shown in Figure 4 performs the difference function. If the resistors ratios are equal (R4 /

R3 = R2 / R1), then VOUT = (Vp – Vn) × R2 / R1 + VREF.

Figure 4. Differential Amplifier

FC321SOT

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