| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem, when a normal maximum output current is doubled, of current consumption increasing in an amplifier, in which an output current Iout corresponding to input signals (Vin, -Vin) applied to two input terminals of the amplifier is transmitted to a load impedance RL connected between two output terminals. SOLUTION: Degenerate differential pairs are employed, in which four transistors (T1, T2, T3 and T4) which use a degenerate impedance Reg having the same value as the impedance RL as a feedback resistor, and control signals (-Vin/2, Vin/2), having a phase opposite to the phase of the input signals (Vin, -Vin), are applied to the upper pair (T3, T4) of the differential pair. Accordingly, the output current Iout of the amplifier can be doubled, without increasing the power consumption. The main purpose of the amplifier is to control the write head of a hard disk.
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