| 摘要 |
The circuit is designed to generate a negative conductance (NG) between two connection terminals (A,B), and comprises two transistors (T1,T2) connected as a differential pair between the two terminals. Two further transistors (T3,T4) are connected between the bases and the collectors of the differential pair transistors, the additional devices implementing feedback which brings negative currents to the bases of the transistors of the differential pair, generating a negative conductance. The collectors of the differential pair transistors (T1,T2) are connected to a supply voltage terminal (VCC) via load resistors (RC), and their emitters are grounded via a current source (10). The additional transistors (T3,T4) are connected as followers, and the emitters are connected to the ground by the intermediary of respective current sources (I1,I2). In a second embodiment, the active-component transistors (T3,T4) are connected as diodes, and resistors are inserted between the emitters of the differential-pair transistors (T1,T2). An oscillator comprising an inductive element and a capacitive element connected to form a resonant circuit for generating a signal having frequency tuneable by the capacitive element, that is the oscillator such as a voltage-controlled oscillator, comprises the proposed circuit connected to the resonant circuit. A receiver for radio-signals comprises an input stage, a mixer, and the oscillator as a local oscillator. |
