In terms of differential amplifiers, what is the functional expression for the virtual ground at Vn?

In terms of differential amplifiers, what is the functional expression for the virtual ground at Vn?

• A. Vn = (R4/R3+R4)V2
• B. Vn = (R3/R4)V2
• C. Vn = (R1/R2)V2
• D. Vn = V2/(R3+R4)

Answer: (A)

The expression for the virtual ground at the inverting input (Vn) of a differential amplifier can be derived from the concept of balanced voltage division between resistors in the feedback network. In a typical differential amplifier configuration, the non-inverting input is considered as the reference point, usually at ground or 0 volts. Because of the feedback and the high gain of the operational amplifier, the inverting input also approaches the same potential as the non-inverting input, which is effectively a virtual ground. To determine Vn, we analyze the voltage division that occurs at the inverting input due to the resistors R3 and R4, which connect the inverting input to the output of the amplifier (which is influenced by V2). The voltage at Vn can be modeled using the voltage divider rule: \[ Vn = \text{Voltage across R4} = \frac{R4}{R3 + R4} \times V2 \] This leads to the functional expression for Vn, which confirms that as V2 varies, the virtual ground at the inverting input adjusts accordingly based on the ratio of the resistances R3 and R4. Therefore, the functional expression that accurately represents the virtual ground at Vn

The expression for the virtual ground at the inverting input (Vn) of a differential amplifier can be derived from the concept of balanced voltage division between resistors in the feedback network.

In a typical differential amplifier configuration, the non-inverting input is considered as the reference point, usually at ground or 0 volts. Because of the feedback and the high gain of the operational amplifier, the inverting input also approaches the same potential as the non-inverting input, which is effectively a virtual ground.

To determine Vn, we analyze the voltage division that occurs at the inverting input due to the resistors R3 and R4, which connect the inverting input to the output of the amplifier (which is influenced by V2). The voltage at Vn can be modeled using the voltage divider rule:

[ Vn = \text{Voltage across R4} = \frac{R4}{R3 + R4} \times V2 ]

This leads to the functional expression for Vn, which confirms that as V2 varies, the virtual ground at the inverting input adjusts accordingly based on the ratio of the resistances R3 and R4.

Therefore, the functional expression that accurately represents the virtual ground at Vn