Twintor in bandstop switched-capacitor ladder filter realisation

An instability problem exists in the design of bandstop SC ladders by stray-insensitive LDI integrators. A second order building block technique has been proposed in to overcome this difficulty. A second order building-block called a twintor (TWinned INTegraOR) is introduced for bandstop SC ladder design. The circuit uses two signal channels to directly realise the basic bandstop operators without term cancellation, and also reduces the required opamp operation speed by a factor of two. Either single-input or differential-input integrators are allowed, giving flexibility for fabrication.