This paper presents a new realization of synthetic transformer using off the shelf active blocks. This proposed transformer is designed using operational transconductance amplifier (OTA), voltage differencing current conveyor (VDCC), resistor and capacitor. Use of VDCC helps to utilizes benefits of both voltage differencing unit and current conveyor. The working of proposed circuit is verified through simulations in LTSPICE using TSMC 180nm process characteristics. The proposed circuit offers the feature of adjusting primary and secondary self-inductances and mutual inductance independently. The bias current of the VDCC is used to control the primary and secondary self-inductance and mutual inductance of synthetic transformer.

This paper presents a new wideband high gain CMOS transimpedance amplifier without using any inductor. In the proposed TIA, gain enhancing path is introduced in the active voltage-current feedback TIA topology to increase both the gain and bandwidth. This path increases the transconductance of the proposed TIA which reduces the input resistance and leads to bandwidth extension. Additionally, for utilizing the benefit of this topology, cascading of common source stage is also done to increase the gain further without deteriorating the bandwidth. Mathematical analysis is also performed to evaluate both the gain and bandwidth enhancement. These analyses are supported by simulations that are done using TSMC 180 nm CMOS technology with the input photodiode capacitance of 0.3 pF. The proposed TIA occupies 0.019 mm2 area and consumes 3.2 mW from the power supply of 1.8 V. Simulation results show that the transimpedance gain of the proposed TIA is 57.15 dBΩ over the bandwidth of 6.5 GHz. The input noise is 17.16 pA/√Hz.