Crystal oscillator - a stable time base

X. 1 30 MHz 30 p series resonance 82608 5V a stable time base The time base shown here uses a crystal for series resonance. This method achieves a greater stability factor than parallel resonance circuits. The two main requirements of the active elements are: 1. The phase-shift between input and output must be 00. 2. Both the input and output must be low impedance, in order that the Q factor of the crystal is not affected. This improves the stability. It therefore follows that a CMOS crystal oscillator cannot cope with the above requirements. A TTL version, although having very little phase shift (up to a frequency of 10 MHz), comes no where near to complying with the second parameter. The circuit described in this article meets both requirements. The design allows frequencies of up to 30 MHz to be produced without any phase shift. Higher frequencies are possible but then T1 and T2 will have to be changed for another type (such as the BFR 91), and the values of R1 ... R4 will have to b