How does a feedback resistor affect output voltage?
2 Answers
A feedback resistor plays a crucial role in determining the output voltage of amplifiers, especially in configurations like operational amplifiers (op-amps).
1. **Voltage Division**: In feedback circuits, a resistor connected between the output and the inverting input of an op-amp creates a voltage divider. This division influences the voltage at the inverting input, which is compared to the non-inverting input.
2. **Gain Control**: The ratio of the feedback resistor (Rf) to the resistor connected to the inverting input (Rin) sets the gain of the amplifier. The output voltage (Vout) can be expressed as:
\[
V_{out} = -\left(\frac{R_f}{R_{in}}\right) V_{in}
\]
where Vin is the input voltage.
3. **Stability and Linearity**: Feedback resistors help stabilize the output voltage by providing negative feedback. This reduces distortion and improves linearity, ensuring the output closely follows the input signal.
4. **Load Impedance**: The value of the feedback resistor can also affect the output impedance of the amplifier. Lower feedback resistor values generally decrease output impedance, allowing better driving of loads.
In summary, the feedback resistor directly influences the gain and stability of the output voltage in amplifier circuits. Adjusting its value changes the output response, allowing for precise control of the amplification process.
1. **Voltage Division**: In feedback circuits, a resistor connected between the output and the inverting input of an op-amp creates a voltage divider. This division influences the voltage at the inverting input, which is compared to the non-inverting input.
2. **Gain Control**: The ratio of the feedback resistor (Rf) to the resistor connected to the inverting input (Rin) sets the gain of the amplifier. The output voltage (Vout) can be expressed as:
\[
V_{out} = -\left(\frac{R_f}{R_{in}}\right) V_{in}
\]
where Vin is the input voltage.
3. **Stability and Linearity**: Feedback resistors help stabilize the output voltage by providing negative feedback. This reduces distortion and improves linearity, ensuring the output closely follows the input signal.
4. **Load Impedance**: The value of the feedback resistor can also affect the output impedance of the amplifier. Lower feedback resistor values generally decrease output impedance, allowing better driving of loads.
In summary, the feedback resistor directly influences the gain and stability of the output voltage in amplifier circuits. Adjusting its value changes the output response, allowing for precise control of the amplification process.