CMOS Voltage Differencing Transconductance Amplifier with Linearly Adjustable Transconductance Gains

In this work, a circuit configuration for the realization the CMOS voltage differencing transconductance amplifier (VDTA) with linear tunable transconductance and wide-input dynamic range is introduced. The circuit design technique is achieved by squaring the long-tail bias current of the differential-input voltage-to-current converter circuit. In addition, the linearity region of the input signal is also improved by using source degeneration technique. The workability of the proposed linearly tunable VDTA has been shown on the construction of the electronically controllable first-order allpass filter circuit. The proposed circuit and its application are investigated and simulated with PSPICE software using TSMC $0.25-\mu \mathrm{m}$ CMOS technology.