Wien bridge oscillator is a combination of op-amp as an amplifier and a Wien bridge network in feedback path. Wien bridge network is made up of four arms. In one arm there is series RC network. In the adjoining arm there is parallel RC network. These two arms are called frequency sensitive arms. Rest two arms consist of two fixed value resistor. This type of network is called lead-lag network because at low frequency it acts like a lead and at high frequency it act like lag.