Oscillators – Automatic frequency stabilization using a phase or frequency... – Particular frequency control means
Patent
1982-07-30
1985-05-21
Laroche, Eugene R.
Oscillators
Automatic frequency stabilization using a phase or frequency...
Particular frequency control means
331115, 331116R, 331132, 331177V, 333217, H03B 536, H03B 706, H03H 1152, H03L 700
Patent
active
045189307
ABSTRACT:
A high-frequency negative resistance circuit for use in a voltage controlled crystal oscillator has a pair of input terminals thereby defining an input current and input voltage. The high-frequency negative resistance circuit includes a sensing circuit for sensing the input current, a biasing voltage source and a load impedance connected to the voltage source. The high-frequency negative resistance circuit further comprises a current mirror circuit connected to the sensing circuit and to the load impedance for producing a current in the load impedance. The current in the load impedance is approximately equal to the input current. The current mirror circuit also controls the sensing circuit to cause the input voltage to decrease as the input current increases. Decreasing input voltage with increasing input current defines the negative resistance. When this negative resistance circuit is configured with a crystal and a voltage controlled capacitance, an oscillator capable of high-frequency operation results. Oscillator parameters such as frequency pullability, startability, stability, temperature, and crystal drive are easily optimized and can be set by mutually independent selection of individual circuit element values. In particular, the crystal drive level is well controlled due to the well-defined limiting character of the negative resistance circuit.
REFERENCES:
patent: 3986152 (1976-10-01), Howell
patent: 4230999 (1980-10-01), Ahmed
patent: 4378531 (1983-03-01), Gawler
Chen William I. H.
Rozema John G.
Hamann H. Fredrick
LaRoche Eugene R.
Mis D. C.
Patti Carmen B.
Rockwell International Corporation
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