| 摘要 |
PURPOSE:To form a quadrature detecting circuit that can work at low voltage (for instance 1V) by switching input of a current source transistors of two balanced mixers by a limiter output signal complementaly. CONSTITUTION:When Vin1+, which is also a limiter output signal, is H, a transistors Q11, Q12 become on, and current iA flows in the transistor Q12. On the other hand, when Vin1+ is H, Vin1- is L, and accordingly, transistors Q13, Q14 become off, and current iB hardly flows in the transistor Q14. When a limiter output signal Vin1+ is L, current iB flows conversely, however, current iA hardly flows. That is, transistors Q11-Q14 and resistances R2-R5 constitute a switch 8 that works complementaly to the limiter output signals Vin1+, Vin1-. A phase shifting circuit 2 is constituted of capacitors C1, C2, a resistance R1 and an inductor L1, and the limiter output Vin1+ is phase shifted and becomes Vin2.
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