| 摘要 |
PROBLEM TO BE SOLVED: To enable a high gain and a high output even in a low voltage operation mode without deteriorating a stable gain control characteristics in a gain variable amplifier circuit. SOLUTION: This gain variable amplifier circuit has two sets of gain control differential pair transistors (13, 15 and 17, and 14, 16 and 18 in the diagram 1) which are cascaded to input differential pair transistors (11 and 12 in the diagram 1) and have an optional emitter area ratio, divided load resistances (21 and 23, and 22 and 24 in the diagram 1) having an optional division ratio and induction elements (19 and 20 of the diagram 1) parallelly connected to the divided load resistances. Thus, a stable gain control characteristics is obtained and the saturation of the gain control differential pair transistors is prevented in the low voltage mode.
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