| 摘要 |
1,140,668. Transistor amplifying circuits. RADIO CORPORATION OF AMERICA. 27 April, 1966 [14 May, 1965], No. 18546/66. Heading H3T. In a transistor amplifier, an interstage coupling includes a capacitor 36, coil 38 and resistor 40 effectively in series between the output of transistor 10 and a point of constant potential, the value of resistor 40 being less than one half the input reactance of the succeeding transistor 50 so that capacitor 36 and coil 38 appear to the output of transistor 10 as a parallel resonant circuit. The low output impedance of the coupling circuit 34 reduces the feedback voltage which arises from the collector-base capacitance of transistor 50. The phase characteristic of the circuit is improved (Fig. 4b, not shown) whilst the impedance transformation provided by circuit 34 stabilizes the gain and bandwidth of the amplifier against variation in input and output impedances of the transistors. Capacitor 36 and coil 38 may be interchanged (Fig. 2, not shown), and either may be variable for tuning purposes. The earthy side of capacitor 36 (or coil 38) may be connected to ground if appropriate bias changes are made. The circuit may be employed as a television I.F. amplifier. |
