Log-domain all pass filter based on integrators

A new all-pass (AP) Log-domain filter is presented. The circuit is based on integrator loop and the current sources. The filter circuit has a very simple structure since it uses only bipolar junction transistors (BJT’s) and a grounded capacitor. The configuration offers large dynamic range at low power supply and higher frequency operation. The filter has a large bandwidth due to its inherent current-mode (CM) nature and Log-domain properties. Phase angle can be electronically tuned through the bias current. The circuit can be implemented in integrated form. PSPICE simulations are given to confirm the theoretical analysis.