전자회로 설계 및 실습 결과보고서: MOSFET Current Mirror 설계

본 내용은 " [중앙대학교 3학년 1학기 전자회로설계실습] 결과보고서8 구매 시 절대 후회 없음(A+자료) " 의 원문 자료에서 일부 인용된 것입니다. 2023.08.30

문서 내 토픽

• 1. Current Mirror

  Current Mirror는 트랜지스터를 전류원으로 이용하여 같은 크기의 전류를 계속해서 만들어내는 회로입니다. 이번 실험에서는 단일 Current Mirror와 Cascode Current Mirror를 설계하고 측정하여 그 특성을 확인하였습니다.

• 2. 단일 Current Mirror

  첫 번째 실험에서는 단일 Current Mirror 회로를 구현하고 측정하였습니다. 실험 결과 MOSFET을 이용해 회로를 설계하면 동일한 전류(Io)가 흐르는 것을 확인할 수 있었습니다. 또한 ΔVo ≡ Io·ΔRo 식을 통해 출력 저항을 계산할 수 있었습니다.

• 3. Cascode Current Mirror

  두 번째 실험에서는 Cascode Current Mirror 회로를 구현하고 측정하였습니다. Cascode 구조를 통해 출력 저항 Ro 값을 증가시킬 수 있음을 확인하였습니다. 실험 결과 Cascode Current Mirror의 출력 저항은 약 Ro ≃ gm·ro2 으로 근사화될 수 있어 기본 단일 Current Mirror보다 출력 저항이 증가하는 것을 알 수 있었습니다.

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• 1. Current Mirror

  Current mirrors are fundamental building blocks in analog circuit design, particularly in operational amplifiers, voltage regulators, and current sources. They are used to replicate a reference current and provide a stable, predictable current to other circuit components. The key advantage of a current mirror is its ability to maintain a constant current ratio, even with variations in supply voltage or temperature. This makes current mirrors essential for creating stable bias currents and ensuring consistent performance across different circuit conditions. Current mirrors can be implemented using a variety of transistor configurations, each with its own advantages and trade-offs in terms of accuracy, bandwidth, and power consumption. Understanding the principles and applications of current mirrors is crucial for designing robust and efficient analog circuits.

• 2. Cascode Current Mirror

  The cascode current mirror is an advanced form of the current mirror that addresses some of the limitations of the single current mirror. It consists of two cascaded current mirrors, where the output of the first mirror is used as the input to the second mirror. This configuration provides several benefits, including: 1. Improved output impedance: The cascode structure increases the output impedance of the current mirror, which helps maintain a more stable and accurate current replication, even with changes in the output voltage. 2. Increased voltage headroom: The cascode configuration allows for a larger voltage swing at the output, making it more suitable for use in high-voltage or low-voltage applications. 3. Enhanced bandwidth: The cascode structure can improve the frequency response of the current mirror, enabling its use in high-speed analog circuits. 4. Reduced sensitivity to transistor mismatch: The cascode configuration is less sensitive to variations in transistor parameters, such as beta and threshold voltage, compared to the single current mirror. The cascode current mirror is widely used in operational amplifiers, voltage regulators, and other analog circuits where high performance, stability, and precision are required. However, the increased complexity of the cascode structure also comes with some trade-offs, such as higher power consumption and the need for more careful design and layout considerations.