A 57μW Logarithmic RF Voltage Detector Integrated with High-Voltage RF Switch

In this work, a low-power logarithmic radio frequency (RF) voltage detector integrated with a high-voltage RF switch is implemented to monitor the RF voltage level applied to the antenna-tuning switch. Excessive capacitance and area introduced by the sensing circuitry is minimized by tapping the lowest stage in the switch transistor stack. A low-power passive linear-in-dB logarithmic voltage detector is designed without utilizing active RF amplifying circuit. A prototype for the proposed concept is implemented in 90nm RF SOI CMOS switch technology. The prototype has a dynamic range of 32dB with a logarithmic error less than ±1dB. The designed circuit consumes 57μW and 131μW when zero RF voltage and RF voltage of 45V are respectively applied to the switch.