Buck-Boost Charge Pump based DC-DC converter

A dual mode buck-boost charge pump is presented in this paper. The two modes, buck and boost, of the CP can be used by the same circuit for degrading or elevating the output voltage, respectively, compared to the input. Each mode can be achieved by switching only the input-output connections without any other change in the design of the DC-DC converter. This dual mode configuration aims to merge two different functions into one circuit minimizing the area the DC-DC converter occupies on the die. The proposed buck-boost CP has been designed using TSMC 130nm complementary metal-oxide-semiconductor (CMOS) technology providing a 3.3V output voltage from a 2.2V supply voltage when the DC-DC converter operates in boost mode and a 1.6V output voltage from a 3.3V supply voltage in buck mode. A 2uF capacitor has been placed at the output of the CP. For the buck mode, the capacitor of the output must be pre-charged in order for the CP to operate properly. © 2022 IEEE

Temperature compensated ring oscillator based VCO

Frequency drift due to temperature variations is a crucial design consideration and cannot always be compensated by a phase-locked loop especially when low-gain, multiband oscillators are employed. A ring oscillator architecture with reduced frequency drift over temperature is presented in this paper. The oscillator is incorporated in a phase locked loop (PLL) to produce a stable clock within the required frequency range under process, voltage, and temperature variations. The output frequency of the oscillator is compensated through a proportional to absolute temperature (PTAT) current in order to eliminate the frequency drift. A proof-of-concept PLL has been designed and fabricated in a 180 nm CMOS technology operating with 3.3 V supply voltage and providing a 480 MHz frequency. Measurement results of the fabricated chip show a frequency variation of the VCO from −1.5 % to + 0.4 % from the center frequency across the temperature range from −40 °C to 120 °C meeting the requirements for most consumer market applications. The duty cycle distortion is less than 1% across the temperature range. The phase noise of the oscillator was measured at −107 dBc/Hz. © 2022 Elsevier Gmb