Digitally controlled non-inverting buck-boost DC-DC converter system

摘要

A digitally controlled non-inverting buck-boost DC-DC converter system including a non-inverting buck-boost DC-to-DC converter control module and a negative feedback module and applicable for a radio frequency circuit module is revealed. By locking a duty cycle to two specific levels, the non-inverting buck-boost DC-to-DC converter control module only needs a single operation mode to achieve the required effects. Simultaneously, pulse-skipping phenomenon is also avoided. Furthermore, a reference voltage is modified through a reference voltage correction circuit of the negative feedback module to eliminate errors between previous DC output voltage and the reference voltage. Thereby the DC output voltage can remain in a stable state so as to reduce operational defects during the mode transition.

主权项

1. A digitally controlled non-inverting buck-boost DC-DC converter system applied to a radio frequency (RF) circuit module, the system comprising:
a non-inverting buck-boost DC-DC converter control module that changes a time ratio of on/off state of switches by a duty cycle to output a DC output voltage in a buck mode or a boost mode in response to a DC input voltage and the RF circuit module is connected to an output end of the non-inverting buck-boost DC-DC converter control module; and a negative feedback module that is connected to an output end of the non-inverting buck-boost DC-DC converter control module and is having a reference voltage correction circuit, a digital compensation circuit, and a digital pulse width modulation module; the reference voltage correction circuit is used for input of the DC output voltage, the DC input voltage and a reference voltage; the reference voltage correction circuit generates and sends a discrete error signal to the digital compensation circuit; then the digital compensation circuit outputs a discrete duty cycle signal to the digital pulse width modulation module after processing; the digital pulse width modulation module outputs the duty cycle after comparing the discrete duty cycle signal with a digital signal whose wave shape is similar to triangular wave so as to control on/off state of switches of the non-inverting buck-boost DC-DC converter control module; thus the DC output voltage of the non-inverting buck-boost DC-DC converter control module follows the reference voltage and reaches a steady state; wherein the reference voltage correction circuit includes a multiplexer, an encoder and an analog to digital conversion circuit; the multiplexer is used to receive a duty-cycle locking signal, and control the output of the DC input voltage or the reference voltage according to the duty-cycle locking signal; the analog to digital conversion circuit is for receiving the DC output voltage; in the encoder, a difference between the output voltage of the multiplexer and the output voltage of the analog to digital conversion circuit is sampled and quantified to generate a discrete error signal; and the duty-cycle locking signal is generated when the reference voltage falls in a non-linear region of the duty cycle.