Novel first-order differential class-AB log-domain allpass filters
The first-order differential class-AB log-domain filters are proposed. They are systematically derived using the statespace synthesis procedure. It is also demonstrated that the present second filter cannot be realized without using differential class-AB type. To the best knowledge of the authors, the filters are the first log-domain first-order allpass filters in the literature. PSPICE simulations are performed using both, bipolar junction transistors (BJT) and ideal devices to confirm the theoretical analysis. Tolerable differences are observed due to BJT non-idealities such as finite-beta, non-zero ohmic junction resistances and early voltages.
allpass filters log-domain filters statespace synthesis differential class-ab circuits