Recently I faced a big problem on designing a on-chip 10kHz LPF which requires me to integrate everything inside the chip without using any extra IC pads or external capacitors.
Could this be possible?
If 'yes', can anyone give me some ideaw on which architecture I should used? gmC? Sallen-Key type? whatever...
Yes, but the Gm-C filter has limited dynamic range and may suffer from linearity issues. You may want to use a fully differential transconductor. As well, the capacitor may have to be tuned if you need a very accurate 3dB bandwidth.
For back of envelope calculations: f3dB ~ gm / 2pi C (ignoring parasitics and 2nd order effects)