Log-domain Universal Biquad Filter Design Using Lossy Integrators
In this paper, a new current mode low voltage log domain Class A universal biquad filter is proposed. The proposed circuit is derived from the block diagram based on Kerwin-Huelsman-Newcomb (KHN) circuit using lossy integrators. The circuit can provide second-order low pass, band pass and high pass filter characteristics. State space method and translinear principle is used for circuit synthesis. The natural frequency f0 and quality factor Q of the circuit is electronically tunable by varying amplitudes of the current sources. PSpice simulation results are given in order to verify the theoretical analysis. The simulations are performed with both ideal transistor models and AT&T CBIC-R type real transistor models.