Preamplifier for magnetic recording and reproducing device

Abstract

Abstract PURPOSE:To improve an SN ratio by applying positive feedback to an input terminal from the positive phase output terminal of a preamplifier, simultaneously applying negative feedback to the input terminal from the inverted output terminal of the preamplifier, reducing input capacity equivalently with the aid of the effect of the positive and negative two feedbacks and making an input resistance appropriate. CONSTITUTION:Since a capacity element connected to the input terminal 3 from the positive phase output terminal 7 of the preamplifier allows a current with a phase the same as an input signal to flow to the input capacity 4 of preamplifier, the element acts as reducing the input capacity equivalently. Meanwhile, a resistance element 6, which is connected to the input terminal 3 from the inverted output terminal 8, allows a current with the reverse phase of the input signal to flow to the input resistance of the preamplifier, that is, the element 6 sucks the current of the input signal to the side of the output terminal, the element 6 acts as reducing the input resistance equivalently. As two positive and negative feedback circuits operate in such a way, the resonance arising between a magnetic head impedance 2 and a preamplifier input capacity 4 becomes a high frequency, compared with no positive and negative feedback circuit made up of capacity elements is used. Simultaneously the negative feedback circuit composed of the resistance element 6 suppresses the sharpness Q of the resonance, whereby a smooth gain frequency characteristic can be obtained in a wide range.

Inventors

• 👤 Fumishige Yatsugi
• 👤 富美繁 矢次
• 👤 Hiroshi Toeda
• 👤 戸枝　広志
• 👤 Masashi Takamiya
• 👤 高宮　正志

Bibliographic Details