SUMMARYA second-generation current conveyor with digitally programmable current gains is presented. A current division network with zero standby power consumption is utilized in two different ways to provide both gain and attenuation of the second-generation current conveyor's current transfer characteristics. The proposed topology overcomes several drawbacks of the previous solutions through affording a more power and area efficient solution while exhibiting relatively wider tuning range and bandwidth. A variable-gain amplifier and a two-integrator-loop filter biquad providing low-pass and band-pass responses are given as application examples. A modified two-integrator-loop topology is developed to offer independent control of the pole frequency and quality factor without disturbing the passband gain. Simulation results obtained from a standard 0.18 µm complementary metal-oxide semiconductor process are given.

New high-order current-mode (CM) filter topologies capable of providing all functions simultaneously are presented. The proposed filters are based on digitally controlled current amplifiers and unity gain voltage buffers. The gains of the current amplifiers are digitally programmed to adjust the filters' transfer function coefficients. It is shown that the proposed approach results in more efficient realizations compared with its counterparts based on other CM active elements. Using BSIM3 0.18 lm CMOS models, simulation results of a fourth-order universal filter are provided.

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SUMMARYA family of new high-order filters capable of providing all filter functions without changing the circuit topology is proposed for integrated circuit applications. The proposed filters are based on simple active elements, namely, digitally controlled current amplifiers (DCCAs) and unity gain voltage buffers (VBs). Gains of DCCAs are digitally programmed to adjust the coefficients of transfer functions. R2R ladders are also utilized to increase the tuning flexibility of the proposed filters. A filter replicating the famous KHN biquad is extended to realize general nth-order filters. Comparison with the recent works shows that the proposed approach results in more efficient realizations compared with its counterparts based on other current-mode active elements. Experimental results obtained from a fourth-order filter implemented using devices fabricated in a 0.35-m CMOS process are provided.

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