The circuit consists of a resistor in series with the voltage source
connected to the inverting
input of the OpAmp. The non-inverting input of the OpAmp is short
circuited to ground(common). A resistor is connected to the output and
provides a negative feedback path to the inverting input terminal.
and Since is connected to
the common or ground terminal, Node 1 is said to be a virtual ground due to the virtual short
circuit between the inverting and non-inverting terminals (which is
grounded) as defined by the voltage constraints, The node voltage method of analysis is applied at node 1,
By appling Equation , obtained from the virtual
short circuit, and the constraint on the current as defined in Equation, Equation is simplified to Solving for the voltage gain, , Notice that the voltage gain is dependent only on the ratio of
the resistors external to the OpAmp, and . The amplifier increases the
amplitude of the input signal by this ratio. The negative sign in the
voltage gain indicates an inversion in the signal.
The output voltage is also constrained by the supply voltages and , Using Equation , the maximum resistor ratio
for a given input voltage
is
实验
根据下图，计算增益和。如果，输出是多少？多大的输入电压幅值，会造成amplifier饱和？
inverting opamp example
Solution:
The output voltage is
independent of the load resistor, , because of the low output resistance
of the OpAmp. Therefore, the gain of amplifier is Using KCL at node a, The currents and
are and Solving for yields,
For and input voltage signal of 由于我使用的是模块，具体参考双电源供电。
