Dual-Mode Multifunctional Reconnection-Less Reconfigurable Filter

A novel solution of a reconnection-less reconfigurable filter is being presented. The filter works in the current mode, voltage mode, and mixed mode (voltage tocurrent) offering sixteen transfer functions in total. The structure utilizes a voltage differencing transconductance amplifier, current follower and voltage, and current amplifiers. The designed structure offers the control of the pole frequency and quality factor and the adjustment of the band-stop/band-pass area of available functions. The proposed design is supported by the PSpice simulations using available simulation models.

A Low-voltage Current-mode Electronically Controllable Four-quadrant Zero/span Circuit

A low-voltage four-quadrant current-mode current-controllable zero/span circuit is discussed. The circuit structure is based on CMOS current follower with adjustable current gain and 4 diodes, without any resistor. The proposed circuit has advantage in such low-voltage architecture biased with as low as ±0.5V power supply. It can generate four-quadrant outputs, without any changing circuit topology. Additionally, its zero and span levels can be independently tuned by electronic method though relative bias currents, where a low-offset output current can be achieved. The total power consumption is approximately 10µW, much lower than a traditional one. Simulation results are shown; it offers good performances of the proposed circuit as depicted. Furthermore, to extend the workability of the proposed zero/span circuit, its application in current-mode Wheatstone bridge to alleviate the offset problem.

CMOS ring oscillator delay cell performance: a comparative study

A common voltage-controlled oscillator (VCO) architecture used in the phase locked loop (PLL) is the ring oscillator (RO). RO consist of number of inverters cascaded together as the input of the first stage connected to the output of the last stage. It is important to design the RO to be work at desired frequency depend on application with low power consumption. This paper presents a review the performance evaluation of different delay cell topologies the implemented in the ring oscillator. The various topologies analyzed includes current starved delay cell, differential delay cell and current follower cell. Performance evaluation includes frequency range, frequency stability, phase noise and power consumption had been reviewed and comparison of different topologies has been discussed. It is observed that starved current delay cell have lower power consumption and the different of the frequency range is small as compared to other type of delay cell.