| 摘要 |
PURPOSE:To establish the crystal oscillator possible for direct frequency modulation having low distortion factor and good frequency linearity, by using the capacitive element of current change type as the load capacitance of crystal oscillator. CONSTITUTION:The third order over-tone crystal oscillation circuit of Colpitts type is constituted with the crystal piece X, transistor TR1, resistors R1-R6, inductances L1-L4, capacitors C1-C10, and transistor TR2 as capacitive element of current change type, and the oscillation output in direct frequency modulation is outputted from the terminal P1 with the signal from the terminal P2. The PN-junction between the base and the collector of the transistor TR2 has the capacitance change rate of a greater value at the fine forward current area and the oscillation frequency is controlled with the base input. The transistor TR2 is for temperature compensation and the resistor R6 and the inductance L4 perform linearity compensation for the transistor TR3. |
