افزاینده امپدانسی جدید قابل کنترل با سیماس (CMOS) با ضریب تقویت کنندگی بزرگ

ABSTRACT A New CMOS Controllable Impedance Multiplier with Large Multiplication Factor

A capacitance multiplier circuit is a useful building block in many very large-scale integration (VLSI) analog circuits, especially for active RC filter and oscillator designs and for cancellation of parasitic elements. Signal processing for biomedical applications is one of the areas where very low frequency filters are used [1–11]. In such a filter, a large time constant is required, which means large values capacitors and/or resistors are required. However, in integrated circuit design, implementing such a large time constant will not be acceptable due to a required large area on the chip and large power consumption. A more viable solution is to use small physical capacitor or resistor and it is scaled up using a simple circuit. There are many impedance-scaling circuits published in the open literature [2–9]. In [2, 3], an operational transconductance amplifier (OTA) based tunable Cmultiplier circuits are developed-multiplier is developed. The design is for capacitor scaling-up only and it uses three OTAs in which the multiplication factor is tuned using the OTAs’ bias currents. An impedance scaler is presented in [4, 5] using MOSFETs. This would require a small area on the chip. However, the scaling factor is controlled by the aspect ratios of the transistors used. This means that, once fabricated, the scaling factor cannot be controlled. The design reported in [6] used three current-controlled current amplifiers in addition to an external resistor. A universal immittance function simulator using a current conveyor is reported in [7]. In this design three CCIIs are used. Moreover, external resistors are used to control the multiplication factor. In [8] current conveyor based R- and-C multiplier circuits are developed. The values of R and C are controlled by two other resistors. In [9] an enhanced grounded capacitor multiplier is presented. The design is based on using the differential amplifier with exponential current scaling. In [10, 11] current conveyors and dual- current conveyors are used.

In this paper, a new impedance scaler is proposed. The design can scale up and down the capacitance and the resistance.