The phase shift oscillator in the diagram uses two all-pass filters, A2 and A3, and an inverting amplifier, A1. The ideal gain for A1, A2 and A3 is 1 when R2=R3, resulting in a loop gain of 1. In ...

In these two circuits, we have resistances of R, 10R and 100R. The absolute values of the resistances aren't critical. It's the value of their ratios that seem to be important. Also note that ...

1. This very-low-frequency sine- and square-wave generator requires few components, but provides low-distortion outputs (derived from LTspice simulator). The output of op amp U1 is applied to the ...