Forward coupled structure with programmable zero points for the synthesis of time-continuous filters, delay lines and the like

摘要

A feedforward structure with programmable zeros for synthesizing continuous-time filters, delay lines and the like, whose particularity is that it comprises a first cell and a second cell which are cascade-connected, each one of the first and second cells comprising a first pair (1, 2) of bipolar transistors in which the emitter terminals are connected to a current source (5), the first pair of transistors being connected to a second pair of transistors (6, 7), a current source (11) being connected to the emitter terminals of the second pair of transistors, a first high-impedance element (C) being connected between the first and second pairs of transistors, a second high-impedance element (C) being connected in output to the second pair of transistors, a fifth transistor (8) being connected between the collector terminal of a first transistor (1) of the first pair of transistors and a collector terminal of a second transistor (2) of the second pair of transistors, the base terminal of the fifth transistor (8) receiving a signal which is taken from the collector terminal of the first transistor of the first pair of transistors and is taken with a positive sign in the first cell and with a negative sign in the second cell, in order to determine a transfer function with a pair of singularities at the numerator, the second transistors (2, 7) of the first and second pairs being controlled respectively by current sources (4, 9) which have mutually different values. IMAGE