公开(公告)号：WO1981003405A1

公开(公告)日：1981-11-26

申请号：PCT/US1981000345

申请日：1981-03-13

Applicant: MOTOROLA INC

Inventor： MOTOROLA INC ,  PACE G

IPC: H03F01/24

CPC classification number: H03H11/1213

Abstract: A configuration of two transistors (Q1, Q2) and two capacitors (C1, C2) provides a current mode second-order active filter for IC implementation with low-pass, bandpass and high-pass capabilities. The filter frequency is tunable over a wide range, independently of filter Q and gain, by varying a DC bias current (Ibias1). The filter can provide one-port impedance functions, and two-port voltage, current and impedance transfer functions. With the addition of a second biasing current source (Ibias2), the filter Q can be controlled by adjusting the ratio of the two biasing current sources. Enhanced dynamic range and large signal performance can be achieved by the addition of linear resistors (R1, R2), with trade-offs in tunable frequency range and frequency linearity.