Impedance matching on-chip

[Ghost Tweaker]

Hi all,

I was wondering if someone could explain me why it is often mentioned that impedance matching is not required onchip. What I currently uderstand is that:

- impedance matching does lead to maximum power transfer but not to maximum voltage transfer.
- for max. voltage transfer, zero output impedance and infinite input impedance is preferred
- onchip, at reasonable frequencies, the distances between the circuits are small with respect to the wavelength and therefore there are no relection problems. High input imedances and low output impedances are therefore preferred for best voltage transfer.

Please let me know if I missed something or if one point is wrong

Regards
Ghost Tweaker

 

[vfone]

Impedance matching is necessarily everywhere, but is not too much room for it in chip design, and engineers generally doing a compromise.

Examples where distances between components are much shorter than wavelength, but where impedance matching plays a very important role, are the HF transceivers (1MHz-30MHz). There (because is a lot of space available) exist impedance matching components between every RF stages.