| 摘要 |
In oscillator circuits equipped with quartz crystals as the frequency-determining element, the problem is to stabilise the drift of the oscillator frequency with temperature, within a wide temperature range of, for example, -40 DEG C to +90 DEG C, in an adequate manner, for example for a relative frequency accuracy of 10<-5>. A solution is specified for this which manages without thermostat and does not require any selected crystals, in which the oscillator frequency is stabilized at the bottom limit of the temperature range by means of a PTC thermistor (Kl) which is connected to a constant voltage source (Uo) and has good thermally conducting contact with the crystal (Q). To stabilize the frequency at the top limit of the temperature range, a capacitance diode (CD) coupled to the crystal is used, the capacitance of which is abruptly raised, above a certain temperature threshold (to), to a higher capacitance value. <IMAGE>
|
