High Performance Current Amplifier

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Date
2006-08
Authors
Gu, Hock Chin
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Abstract
A high bandwidth class AB current amplifier by using few compensation resistor technique and current mirrors is presented and analyzed. The simulation results are obtained using TSpice tool using 0.35~m CMOS TSMC process, at 2.5V power supply. The amplifier utilizes Class AB amplifier topology to achieve high bandwidth. The current amplifier realized with only ten MOS devices, where will always provides very low input resistance, good large signal behavior and GHz bandwidth. Such technique stands as a powerful method of bandwidth enhancement for general circuit using CMOS current mirrors. The original circuit without compensation resistor technique contributes about 5.3 MHz bandwidth and the presented bandwidth is being enhanced from 1 GHz for the uncompensated current amplifier to about 1.13 GHz for the compensated one without affecting the current gain to 2% precision. Besides, the presented amplifier has very low power dissipation and it is about 1.75mW with the current supply for the circuit is about 112~, so heat sink is not require which provides space saving and cost saving. This amplifier is able to operate at 2.5V supply voltage and it is a standard for the CMOS technology. The simulation result shows the circuit will perform as a good current amplifier at input impedance of 1060 and output impedance 37kO and current gain 20dB. It is the basic for a good current amplifier which always required low input impedance and high output impedance. The phase margin and gain margin of the presented amplifier is about 55deg and -lldB. Since the gain margin is negative and phase margin is about 60deg, theoretically no oscillation are possible for this circuit and the amplifier can perform stable at high frequency.
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A high bandwidth class AB current amplifier by using , few compensation resistor technique
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