Browse Prior Art Database

Wide-Range, Variable-Frequency Oscillator Circuit

IP.com Disclosure Number: IPCOM000039844D
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Bhatia, HS: AUTHOR [+3]

Abstract

The new circuit described consists of a series of logic gate circuits connected together in a closed loop to form a "ring" oscillator with the period of oscillation equal to the sum of the delays in the loop. A unique feature is the inclusion of an address register/decoder which controls the number of stages included in the loop and, therefore, the frequency of oscillation. This manner of control permits covering a wide frequency range by digital means. Fig. 1 shows a block diagram of a typical logic gate circuit which is used to form a stage of the ring oscillator. Control signal 3 determines which input terminal, 1 or 2, is active. The signal on the active input terminal, either 1 or 2, produces a "true", same polarity, signal on output 4. The "complement" output 5 always has the opposite polarity of output 4.

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Wide-Range, Variable-Frequency Oscillator Circuit

The new circuit described consists of a series of logic gate circuits connected together in a closed loop to form a "ring" oscillator with the period of oscillation equal to the sum of the delays in the loop. A unique feature is the inclusion of an address register/decoder which controls the number of stages included in the loop and, therefore, the frequency of oscillation. This manner of control permits covering a wide frequency range by digital means. Fig. 1 shows a block diagram of a typical logic gate circuit which is used to form a stage of the ring oscillator. Control signal 3 determines which input terminal, 1 or 2, is active. The signal on the active input terminal, either 1 or 2, produces a "true", same polarity, signal on output 4. The "complement" output 5 always has the opposite polarity of output
4. The particular logic circuit configuration chosen could be from any circuit family, or even a mixture of different circuits. Typically, for a high-frequency oscillator, a current- switch, emitter-follower circuit might be used. Fig. 2 shows a block diagram of the overall system. The ring oscillator consists of logic gate circuits 6A through 6N. The true output of each stage is connected to the input terminal 1 of the succeeding stage. (The time output 4 of the last stage 6N is left unused. Input 1 of the first stage 6A also remains unused.) For completing the feedback loop to make the system oscillate, the complement output 5 of gate 6N is connected to input terminals 2 of all the stages. The particular gate that has its input terminal 2 activated by a control signal 3 determines the starting point of the ring, and therefore the number o...