Mosfet based filter and oscillator circuits

Analog filters are used for communication and signal filtering uses. While passive filters are implemented with resistor, inductor, and capacitor circuit elements; in addition to these elements in passive filters, it can also be realized with active circuit elements such as OTA, and current conveyor, which has become widespread recently, mainly OPAMP. Passive elements cause the use of many limiters in filters. In passive filters, high-value elements are used when it is desired to work at low frequencies. This causes it to take up more space on the integrated circuit and the cost increases. This also increases power consumption. As with passive filters, active filters with OPAMP or current conveyors use a large number of transistors and passive elements, so the chip area they occupy on the IC is large. Since the bandwidth of OPAMPs is limited, it can be difficult to design filters at desired frequencies. Instead of the circuit elements used in active filters, there are with MOSFETs designed filters that have been used in recent years, so filters are created with the internal parameters of the MOSFET instead of resistors and capacitors. This method uses the gate-source capacitance and the transconductance (gm) of the MOSFET. Thus, less chip area, cost, and power consumption are provided. In addition, MOSFET-based circuits can operate at high frequencies. In this thesis, based on the studies available in the literature, eight filter circuits and one oscillator circuit have been proposed by changing or improving the previously proposed circuits. All filter circuits are current-mode and transresistance mode, all designed circuits have single input multiple outputs and operate at low supply voltages. After the filter types were determined by obtaining the equation results of the circuits, the designed circuits were simulated in the LTSpice program using 0.18 µm TSMC CMOS parameters. Equation results were checked by making ideal simulations of the circuits. Afterwards, biasing have been made with current sources and the closest values to the ideal results were tried to be obtained by using MOSFETs suitable for CMOS technology instead of current sources. The power consumption of the circuits has been determined, and the power consumption of the proposed circuits is below 100 µW, except for one circuit, only one circuit is at the level of 350 µW and they have low power consumption. Monte Carlo and THD Analyzes were performed to observe the performance of the circuits. Simulations of the five proposed filter circuits have been carried out with Spice models of commercially integrateds ALD1106 and ALD1107, and the frequency response has been obtained. An experimental application has been made for two of these circuits. For the other circuits, and the experimental application of these circuits is planned. With the proposed final filter circuit, the oscillator was designed and thus a sinusoidal signal has been produced. In the oscillator circuit, as in the proposed filter circuits, the design of the circuit is made using a small number of MOSFETs and two capacitors.