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# Oscillator Circuit

IP.com Disclosure Number: IPCOM000078520D
Original Publication Date: 1973-Jan-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 30K

IBM

## Related People

Hansen, KM: AUTHOR [+2]

## Abstract

Shown is an oscillator circuit using complementary field-effect transistors.

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Oscillator Circuit

Shown is an oscillator circuit using complementary field-effect transistors.

Conventionally, an oscillator requires two electrical feedbacks; a negative feedback to stabilize the circuit around a linear point, and a positive feedback to unbalance the operating point, so that the circuit goes from one region of cutoff to another region of cutoff. The positive feedback is generally a feedback whose value is frequency dependent. A resistor, capacitor, inductor network, or crystal with equivalent electrical characteristics can be used to provide this feedback. A negative feedback is generally not frequency dependent. These elements are contained in a circuit illustrated in Fig. 1.

Transistor T1, T2 and resistor R1 provide the negative feedback. A circuit containing only these three devices will attempt to bias itself into linear signal region (which by misnomer corresponds to the saturated region of transistor operation). Nodes N1 and N2 which are coupled by resistor R1, assure that the voltage at these nodes are somewhere in between the value of the power supplies. The operating point or the value of the node voltage may be adjusted by adjusting the W/L of transistors T1 and T2.

To illustrate operation of the circuit, it may be assumed that N2 in Fig. 1 is a ground potential. Thus, since there is no DC path to N2 accept through resistor R1 (CR1 is a DC open), N1 as a result must also be at ground. A positive DC change in N2 will couple through R1 to N1 forcing the T2 device on harder, and the T1 device off more, and thus return N2 to ground.

Transistors T...