A realization of a wide‐band second‐generation current conveyor by using complementary transistors

Abstract

AbstractAlthough a number of realization circuits for second‐generation current conveyors (CCII) and their applications to active RC networks have been reported, the bandwidth of CCII itself is not sufficient. It is pointed out that one of the causes of degradation of the RF characteristics of the CCII using the complementary transistors is the effect of signal current flow through the collector capacitance Cc. A method is described also for broadband operations by compensating this effect actively. In practice, a transistor with the gain bandwidth product fT of 100 MHz is used for construction of a positive‐type CCII. The voltage transfer factor and the impedance looking into the X terminal have improved with or without compensation while the current transfer factor has improved with compensation so that those are almost ideal characteristics within the measurement up to 10 MHz. The magnitudes of the impedances looking into the Y and Z terminals decreased beyond about 100 kHz due to the effect of the stray capacitance of each terminal and fT. However, there is improvement as the magnitude is larger by an order than the uncompensated case. As an application, the compensated positive‐type CCII is used for construction of a biquad low‐pass filter with the pole frequency of about 3 MHz. The operation was satisfactory.