GB1322366A - Wide deviation voltage controlled crystal oscillator - Google Patents

Abstract

1322366 Voltage controlled oscillators; crystal oscillators WESTINGHOUSE ELECTRIC CORP 6 July 1970 32657/70 Headings H3R and H3T In a voltage controlled oscillator, the resonator (see Fig. 7) comprises a crystal 12 operated at its series resonant frequency, and an arrangement 22, 24 for neutralizing the static capacitance of 12 and providing a linear reactance versus frequency characteristic, a voltage variable capacitance device 26 with associated elements such as inductor 28 for providing a reactance versus voltage characteristic varying linearly about zero value of reactance and an impedance transforming network 36, 38, 42 resulting from application of Norton network transformation (Fig. 5, not shown) coupled between the crystal 12 and the device 26 for employing low impedance level components in association with the device 26. In the oscillator proper shown at Fig. 10, the combined inductance 46 shown at Fig. 7 is constituted by the secondary winding of a transformer 68 employed in a feedback circuit for the maintaining amplifier 72 and including a frequency selective network 90-98 for suppressing oscillations below the desired frequency band. The oscillator output is applied via a buffer amplifier 100, 102 to an output stage involving transistors 104, 106, Transistor 106 neutralizes any positive feed-back occuring via the collector base capacitance of 104. A tuning voltage is applied at 60 to the variable capacitance diodes 52-55.