A near-field modulation chopping stabilized injection-locked oscillator sensor for protein conformation detection at microwave frequency

A near-field modulation chopping technique is implemented in an injection-locked oscillator sensor for the detection of protein conformation changes. With the addition of shielding electrodes, the signal is chopped by electronically switching the paths of the displacement sensing currents while minimizing the up-conversion of the 1/f noise. To maximize the dynamic range, feedback-around-sensor utilizing embedded varactors is applied. A 16-GHz prototype in 65-nm CMOS demonstrates the techniques lower the 1/f corner frequency from 10 to 0.25 kHz while achieving 74.5 dB of dynamic range. Bio-molecular sensing is validated with thermal-cycled bovine serum albumin (BSA) solutions at different conditions.