Dual MOSFETs equivalent resistor

This paper presented a method to implement resistor's function by two MOSFETs. Both of the MOSFETs' sources and drains were connected together and the sources were connected to the ground. One MOSFET works in saturate area while the other works in non saturate area. The results show that: the linearity error of the resistor is below 5%; the outpout voltage can vary from 1V to 4V; the value of the resistor can be adjusted easily ranging from 1kΩ to tens kΩ; the resistor can be made through standard CMOS process.