I am building a low pass filter IC in 0.25 micron CMOS. My design requires 14 Mega-Ohm resistors. I want to replace them with an active load in order to save space. If possible I would like to use a current source as a resistor.
What would be the most simple and compact design?
I've already tried switched capacitors but had various difficulties, including NOC generation.
A simple floating gate MOSFET would require a transistor length of 2000 microns. If worst comes to worst I'll work on balancing transistor size with capacitor size.
Thanks a lot.
Edit: Topology is Shallen key. Output should be a decent sine wave of frequency 20kHz.
R1 =R2=14MOhm and C1 = C2= 0.56pF.