DYNAMIC BIAS CURRENT-STARVED INVERTER AND LOW-POWER DELTA-SIGMA MODULATOR USING THE INVERTER

摘要

A bootstrap capacitor is installed between gates of a pair of cascade-connected PMOS transistors, and between gates of a pair of cascade-connected NMOS transistors, respectively. In a data sampling step (F1), all of the PMOS transistors and NMOS transistors are weakly inverted through current starvation such that charges corresponding to the potential differences between an input voltage (VIN) and reference voltages (VBP, VBN) are stored in a bootstrap capacitor. In a charge transfer step (F2A), the input voltage strongly inverts one of the NMOS transistor pair or the PMOS transistor pair according to polarity, and the remaining pair is cut off, thereby securing a broad bandwidth. Following the charge transfer, in a normal state step (F2B), all of the PMOS transistors and the NMOS transistors return to the weak inversion state so as to achieve a high gain and prevent power waste.