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A new digitally programmable universal current-mode biquad filter is proposed. The filter is based on digitally controlled current followers (DCCFs). It utilizes gains of the DCCFs to provide precise frequency and/or gain characteristics that can be digitally tuned over a wide range. All parameters of the proposed filter can be adjusted independently. Experimental results obtained from a 0.35-[micro]m standard CMOS chip are provided. Index Terms--CMOS analog integrated circuits, current-mode (CM) filters.

A CMOS fully integrated 12th-order bandpass filter for low interemdiate frequency Bluetooth receivers is presented. The design is optimized to meet the selectivity and dynamic range requirements of Bluetooth while consuming relatively low power. The filter is based on unity gain cells and utilizes linearized MOSFET resistors for tuning. It exhibits a bandwidth of 1 MHz and a programmable center frequency range of 2 to 4 MHz. Experimental results obtained from a standard 0.5-[micro]m CMOS chip show that the filter exhibits an in-band dynamic range of 53.3 dB at gain of 0 dB, and 52 dB at gain of 15 dB, while consuming a total current of 1.32 mA. Attenuations of more than 10, 38, and 55 dB, are achieved for blockers one, two, and three, respectively. Index Terms--Bluetooth (BT) receivers, CMOS analog integrated circuits (ICs), current mode circuits, intermediate-frequency (IF) bandpass filters.

The design and implementation of a high performance CMOS fully balanced second-generation current conveyor (FBCCII) is presented. The proposed circuit is essential to extend the use of the CCII based circuits to integrated circuits (ICs) applications. The circuit is developed by applying the current sensing technique to a fully balanced version of a differential difference amplifier (DDA). A low power class AB circuit realization is implemented in a 1.2-[micro]m CMOS technology and its different characteristics are measured. Design examples of realizing fully balanced variable gain amplifiers (VGAs) and a bandpass filter based on the proposed FBCCII are given. Experimental results of the proposed circuits are included. Index Terms--Current-mode circuits, filters, second-generation current conveyor (CCII), variable gain amplifiers.

This paper presents design and implementation of CMOS fully balanced realization of the four-terminal floating nullor (FTFN). The proposed fully balanced FTFN (FBFTFN) is an essential building block for implementing fully balanced architectures of both voltage and current-mode analog CMOS integrated circuits (ICs). A low-power class AB CMOS realization of the proposed circuit is fabricated in a 1.2-/[micro]m technology. The proposed circuit has numerous applications. Several applications including fully balanced amplifiers, filters, and sinusoidal oscillators are presented. All proposed design techniques and circuits are experimentally verified. Index Terms--Amplifiers, current-mode circuits, filters, four-terminal floating nullor, mixed-mode analog integrated circuits, sinusoidal oscillators.

This brief presents the fully balanced version of the differential difference amplifier (DDA) as an essential building block for implementing fully differential architectures of analog CMOS integrated circuits (ICs). We demonstrate that the fully balanced differential difference amplifier (FBDDA) provides the solution for systematically developing fully differential versions of any single-ended op-amp based circuit. We also show that, unlike the DDA, the FBDDA exhibits a wide input range without demanding complex circuitry. A low-power class AB CMOS realization of the proposed circuit has been designed and fabricated in a 1.2-[micro]m technology. All proposed design techniques and circuits were experimentally verified. Index Terms--Amplifiers, CMOS analog integrated circuits, filters, fully balanced differential difference amplifier, fully differential op-amp circuits, mixed-signal VLSI.

SUMMARY A 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. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY A 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-µm CMOS process are provided. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Presents a study which proposed a balanced version of the differential difference amplifier (DDA) for analog complementary metal oxide semiconductor integrated circuits. Applications of DDA; Implementation of the fully balanced DDA (FBDDA); Applications of FBDDA; Conclusion.