Design and Performance Analysis of a Low-Power Multistage Amplifier for Portable Applications using LTspice
Keywords:
Internet of Things (IoT), Low-power amplifier, LTspice simulation, Multistage amplifier, Voltage gainAbstract
This study presents the design and simulation of a low-power multistage amplifier intended for modern portable electronic systems. With the rapid expansion of wearable sensors, biomedical monitoring devices, and Internet-of-Things (IoT) technologies, there is a growing demand for analogue circuits capable of delivering high performance while maintaining minimal power consumption. Many of these devices operate using small batteries or energy-harvesting sources, making energy efficiency a critical design requirement. In such systems, analogue amplifiers serve as essential components because they amplify weak electrical signals generated by sensors so that the signals can be accurately processed by subsequent electronic stages. Conventional amplifier designs generally emphasise high gain and wide bandwidth; however, these improvements often lead to higher power dissipation, which is undesirable for portable applications. Consequently, recent research has focused on developing amplifier architectures that preserve strong amplification performance while reducing energy usage. Low-power amplifier design has therefore become a significant area of interest in analogue integrated circuit research. The proposed amplifier architecture consists of three functional stages. The first stage is a differential input stage that performs the initial signal amplification while improving noise rejection and signal accuracy. The second stage operates as the main gain stage, providing substantial voltage amplification while maintaining stability and low power consumption. The third stage functions as an output buffer that isolates the amplifier from the load and enhances its ability to drive external circuits without degrading performance. Simulations performed in the LTspice environment with a 1.8 V supply demonstrate that the amplifier achieves approximately 95 dB voltage gain, a gain-bandwidth product near 1.1 MHz, and total power consumption below 200 µW, indicating a well-balanced and energy-efficient design.
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