CMOS First-Order All-Pass Filter With 2-Hz Pole Frequency
Abstract : A CMOS fully integrated all-pass filter with an extremely low pole frequency of 2 Hz is introduced in this paper. It has 0.08-dB passband ripple and 0.029-mm2Si area. It has 0.38-mW power consumption in strong inversion with ±0.6-V power supplies. In subthreshold, it has 0.64-µW quiescent power and operates with ±200-mV dc supplies. Miller multiplication is used to obtain a large equivalent capacitor without excessive Si area. By varying the gain of the Miller amplifier, the pole frequency can be varied from 2 to 48 Hz. Experimental and simulation results of a test chip prototype in 130-nm CMOS technology validate the proposed circuit.
? This paper has presented a new voltage-mode first order all-pass filter employing one FDCCII, one grounded capacitor and resistor.
? The salient features of the proposed circuit is use of grounded capacitor, suitable for IC implementation, providing inverting and non inverting voltage-mode all-pass responses simultaneously from the circuit and also providing one of the voltage output at low impedance thus making them suitable for voltage-mode cascading.
? This element is a versatile building block whose applications exist in the literature.
? Some voltage-mode circuits benefit from minimum component feature and hence require no matching constraints.
? Temperature dependence and manufacturing tolerances are common problems in all continuous time integrated filters.
? A voltage-mode all-pass filter with minimum component is expected to use two passive components and one active element.
? Two component based circuits are free from matching problems as both pole and zero frequency depend on the same two components such circuits would benefit from easy control over the pole frequency, as only a single element need to be controlled unlike the circuits require three components.
? This feature not collectively exhibited in any of the reported work in the literature, including the most recent and useful circuit.
• The proposed circuit demonstrates a high linearity and consumes merely 16 mW power from a 1.8-V supply.
• A new first-order voltage-mode filter employing minimum active and passive components is proposed.
• The proposed configuration employs one differential voltage current conveyor (DVCC), one grounded capacitor and one resistor.
• In this paper, the authors proposed a simple first-order filter employ minimum active and passive components.
• The proposed circuit can realize first-order lowpass, highpass and allpass filter responses in the same configuration and still enjoys all of the above features.
? In these circuits the current rather than the voltage is used as the active variable either throughout the whole circuit or only in certain critical areas.
? The use of current-mode active devices has many other advantages such as larger dynamic, higher bandwidth, greater linearity, simple circuitry and low power consumption compared to that of voltage-mode counterparts for example operational amplifiers.
? Due to a simple structure and appropriate performance of the proposed all-pass filter, this filter achieves a flat group delay of over 60 ps with a pole/zero pair located at 4.5 GHz.
? If the useful frequency range of the proposed filter is limited in, the influences of parasitic elements to the coefficient n will be diminished.
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