Wien bridge oscillatorb

Shown are two different Wien bridge oscillators connected . Among them,
the negative feedback loop of the circuit shown in Figure (a) uses resistors Ri and Rz as
a voltage divider circuit. The bridge oscillation circuit can be regarded as a positive-phase amplifier circuit. Its input signal is the output signal fed back through a lead-lag circuit. to the input terminal
. The amplifier in Figure (b) is connected across a bridge circuit. One end of the bridge circuit is a lead-lag circuit, and the other end
is a voltage divider circuit.