This paper proposes an ultra-high-gain wideband CMOS transimpedance amplifier (TIA) for driving the ultrahigh-motional-resistance MEMS resonator. A phase compensator made by a tunable capacitor and resistors provides a lead phase
compensation for the TIA. Moreover, the compensator produces a stable input bias voltage for the inverted-based Cherry Hooper amplifier, whose output bias is stabilized by tunable transistors. The common-gate amplifier uses a high-resistance load resistor to ensure a gain of 80 dBΩ, and the Cherry-Hooper amplifier uses a high-gm inverter and a high feedback resistor to provide a gain of 35 dB. A dual power supply of 1.2/1.8 V was used to save power. Based on the 0.18 μm CMOS process, the TIA simulation shows the gain is 118 dBΩ, the bandwidth is 190 MHz, the input-referred current noise is 20.9 pA/√Hz, and the power without test buffer is only 0.45 mW. The MEMS oscillator starts up within 0.5 ms with a swing of 1.128 Vp-p, and the phase noise is -96.59 dBc/Hz, 99.2 dBc/Hz at 10 kHz and 100 kHz offset, respectively.