What is Stray Capacitance ?

[shahkushan1]

Regarding Capacitors :

What is Stray Capacitance ?

Actually the entire sentence goes like dis & i cant understand it :

In an inverted R/2R ladder DAC node voltages remain constant with changing inp
ut binary words..This prevents any slowdown effects by STRAY CAPACITANCES

 

[WimRFP]

Regarding Capacitors :

Hello,

Stray capacitance is the capacitance that occurs due to electric stray fields. Imagine an open (non terminated) trace above a ground plane. Normally this is assumed to be connection without inductance, resistance and capacitance. Reality is different however (depending on what you are doing).

Put a voltage source between the trace and ground and an E-field will exist around the wire and especially between the ground and the trace. To establish this E-field, a charge must be supplied. The ratio between the applied voltage and the charge that flows into that open ended trace is called capacitance. you have to think of values below 1pF/cm trace length.

If you put an AC source between the open ended trace and ground, there will be a small current because of the capacitance caused by the trace with respect to ground.

As it is caused by the stray field, it is called stray capacitance. You can model the effect of the trace capacitance (stray capacitance) with a real capacitor. In many applications stray capacitance is undesired as it slows down voltage changes, hence speed.

One can reduce the effect of stray capacitance by making sure there is no voltage difference between the conductors that are involved. In instrumentation guard rings are used to reduce the effect of leakage and stray capacitance.

Reading your text, they also keep the voltage constant so that you don't have to charge and discharge the stray capacitance. Stray capacitance can be far below 1pF, but in fast high impedance circuits, it may slow down the electronics.

In case of high-speed circuits, parasitic inductance becomes important also. The capacitance in combination with the inductance results in a transmission line. One must account for this during the design of PCBs for high-speed circuits.

 

[fcfusion]

Re: Regarding Capacitors :

To put it simple, resistors present an additional (and undesirable) capacitance.

Larger resistors present larger stray capacitances.

 

[dick_freebird]

Stray capacitance is the net sum of all the capacitances you
failed to account for and model, in design.

 

[dlhylton]

Stray capacitance is unwanted and unintended capacitance in a circuit.

This can be caused by long wires running parallel to each other or long component leads of components such as from capacitors or inductors.

See
http://www.learningaboutelectronics.com/Articles/What-is-stray-capacitance
to see a full article on this