Articles

Frequency Response of Electronically Tunable Current-Mode Third Order High Pass and Low Pass Filter for Q = 10

The circuits using current-mode (CM) building blocks have received considerable attention in many filtering and signal processing applications. Compared to their voltage-mode(VM) counterparts, the current-mode building blocks are attractive because of their wider bandwidth, higher slew rate, and lower power consumptions. In IC technology, it is desirable to operate circuits at low voltages which can be achieved by using CM building blocks. As a large number of op-amp based circuits with elegant realization procedures are already available, it is worthwhile to convert them into the circuits based on current-mode building blocks. In this paper, a realization of a current mode third order high pass and low pass filter is described. The proposed circuit employs operational amplifier as the basic building unit. The filter circuit realizes quadratic work function. It provides electronically tuning capability of the filter characteristics. The proposed circuit works ideal for Center frequency fo= 10 k and Circuit merit factor Q > 1. The gain roll-off this configuration is 18dB/octave. The circuit is suitable for monolithic integration and high frequency operation. The filters developed were successful in obtaining passive sensitivities less than unity in magnitude and active sensitivities are half in magnitude, which is a noteworthy achievement. The circuit is suitable for high frequency operation and monolithic integration.

Electronically Tunable Third Order Feed Forward CM Band Pass Filter for Q = 10

A new electronically tunable current-mode third order filter is proposed in this paper. OP-AMP is used as an active building block. With current input the filter can realize band pass responses in current mode. The filter circuit realizes calculated transfer function. The other attractive features of the filter are a) Employment of minimum active and passive elements b) Responses are electronically tunable c) Low active and passive sensitivities d) Suitable for high frequency operation e) Ideal for integrated circuit implementation.