# Oscillator Frequency of a Ring Oscillator with RC feedback

• jaus tail
In summary, the conversation discusses the functioning of an oscillator and the effects of different component values on its operation. A similar circuit is referenced, but there are doubts about its effectiveness with the current component values. The use of TTL gates is also questioned and it is suggested that CMOS gates may be more suitable.
jaus tail
Homework Statement
What is frequency of oscillator in below circuit?
Relevant Equations
f = 1/(2*3.14*R*C)

I'm not sure how will this oscillator work. Assume A is low, so B will be high and the capacitor will charge through B-C- 2Mohm.
Now even D has gone high, so A will be high and B will be low and C will discharge. I'm not sure how the voltage divider rule across RC will take into effect.
I found a similar structure in this link (3rd circuit diagram):
https://www.gadgetronicx.com/square-wave-generator-logic-gates/Ref: Gadgetronix Square Wave Generator Using Logic Gates. But I'm not sure how if the two circuits will work same as position of Capacitor is after 2nd inverter in the diagram in link.

How will the C charge and discharge here?

The circuit from your link has different component values, and lists an equation for the frequency of oscillation. I haven't tried this type of oscillator before, so I need to think a bit more about it to understand how it works...

jaus tail
Since these are TTL gates with fairly low input impedances I doubt this circuit would work. I think you'd have to pull pretty hard voltage-wise to get the input to go low, like maybe -50V thru a 50K resistor to produce 1mA fan-in.

Probably intended for CMOS like 74Cxx or rca 4000 series.

jaus tail and Tom.G

## What is an oscillator frequency?

An oscillator frequency is the number of cycles or oscillations a device or circuit produces in a given unit of time. It is typically measured in Hertz (Hz) and is a measure of how fast the oscillator is vibrating or oscillating.

## What is a ring oscillator with RC feedback?

A ring oscillator with RC feedback is a type of electronic oscillator circuit that uses a ring of inverters connected in a loop and a capacitor for feedback. The RC feedback helps to control the oscillation frequency of the circuit.

## How does the RC feedback affect the frequency of a ring oscillator?

The RC feedback affects the frequency of a ring oscillator by controlling the charging and discharging of the capacitor, which in turn affects the time it takes for the signal to propagate through the inverters in the ring. This results in a longer or shorter oscillation period and therefore a different frequency.

## What factors can affect the oscillator frequency of a ring oscillator with RC feedback?

The oscillator frequency of a ring oscillator with RC feedback can be affected by factors such as the values of the resistors and capacitor used in the circuit, the temperature, and the supply voltage. Any changes to these factors can alter the charging and discharging times of the capacitor, thus affecting the frequency of the oscillator.

## How can the oscillator frequency of a ring oscillator with RC feedback be calculated?

The oscillator frequency of a ring oscillator with RC feedback can be calculated using the formula: f = 1/(2πRC). Where f is the frequency in Hertz, R is the resistance in ohms, and C is the capacitance in farads. This formula takes into account the time constant of the RC circuit and the number of inverters in the ring.

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