Operational Amplifier And Its Array Low Power Consumption Design And Research

Low power design methodology is studied from two levels, single operational amplifier and amplifier array, when supply voltage remains fixed and amplifier high performance is maintained. FOM (figure of merit) is introduced as a measure of power efficiency.On single op-amp level,"gain bandwidth" and "phase margin" are analyzed, and thus leading to a high-speed low-power amplifier design methodology, which can provide a process to design operational amplifier for amplifier array. Power consumption of operational amplifier can be divided into two main parts:the first part is the power consumption to ensure high-frequency position of unity gain bandwidth, which is an essential consumption and can’t be substantially reduced when supply voltage is constant. The second part is the power consumption to increase the second pole position for an enough phase margin. Different op-amp structures have different power demand to keep the same position of the second pole when the unity gain bandwidths are same. This leads to a low-power consumption way of designing high-speed op-amp when power supply is constant: reduce power consumption of op-amp by select low power circuit. Based on TSMC0.18um1P6M CMOS process model, using the Cadence simulation tools, a unity-gain bandwidth of960MHz, low-frequency open-loop gain81.42dB,72°phase margin, high-speed high-gain operational amplifier is designed. The power consumption of the overall circuit is17.34mW when power supply voltage is1.8V, which achieves the desired design requirements.Amplifier array level is the focus and highlights of this paper, which leads to the power consumption analysis of single op-amp closed-loop system and amplifier array by analyzing frequency characteristics of the two closed-loop system. Amplifier array allocate the closed-loop system magnification to subsystems, which greatly reduces the performance demand for high-speed operational amplifier, leading to the reduction of power consumption of each amplifier. The overall power consumption of the amplifier array is less than the single op-amp closed-loop system when the signal processing speed and maximum magnification are the same. In addition, the array design can reduce the power by50%or more, by choosing reasonable array of combinations and keeping unused subsystems power off. Amplifier array provides a new perspective of low power consumption design.