Dual bootstrap sampling switching circuit for low voltage application

Abstract

The invention relates to the technical field of CMOS analog integrated circuit design. The dual bootstrap sampling switching circuit for low voltage application comprises a charging circuit, a switching voltage control circuit, a charging capacitor unit and a sampling switch path. The charging capacitor unit comprises charge capacitors Cb1 and Cb2. When a clock signal clkb is at the first level, the charging circuit is used to control the power supply voltage to charge the charge capacitors Cb1 and Cb2 in parallel, and the control terminal of the sampling switch path is grounded to turn off the sampling switch path. When the clock signal clkb is at the second level, the switching voltage control circuit is used to control the charge capacitors Cb1 and Cb2 connected in series to power the control terminal of the sampling switch path, so that the sampling switch path is turned on for sampling. According to the invention, the double increase of the switch control voltage is realized underextremely low power supply voltage; turn-on and turn-off of the sampling switch path are completed; and the signal sampling accuracy is high.

Description

technical field [0001] The invention belongs to the technical field of CMOS analog integrated circuit design, in particular to a double bootstrap sampling switch circuit for low voltage application. Background technique [0002] In wearable physiological signal detection chips, the power supply voltage of the low-power successive approximation analog-to-digital converter may be as low as 200-300mV. The threshold voltage of the transistor is still maintained at about 300mV. If the traditional gain bootstrap switch is still used to complete signal sampling, the power supply voltage is close to or lower than the threshold voltage of the transistor at this time, which may easily cause the switch transistor to fail to conduct. Even if the power supply voltage is equivalent to the threshold voltage of the transistor, it only makes the switching transistor in a weak inversion state, which will still cause a significant drop in signal sampling accuracy. Contents of the invention ...

AI Technical Summary

Problems solved by technology

If the traditional gain bootstrap switch is still used to complete signal sampling, the power supply voltage is close to or lower than the threshold voltage of the transistor, which may easily cause the switch transistor to fail to conduct

Even if the power supply voltage is equivalent to the threshold voltage of the transistor, it only makes the switching transistor in a weak inversion state, which will still cause a significant drop in signal sampling accuracy

Images