Hong Kong Applied Science and Technology Research Institute Company, Limited

Xiao Fei Kuang

Kam Chuen Wan

Kwok Kuen (David) Kwong

Kwok Kuen David Kwong

Kwai Chi Chan

Yat To William Wong

Yat To (William) Wong

A bandgap reference circuit has trimming-up resistors and trimming-down resistors for bi-directional trimming. PNP transistors have base and collectors grounded and emitters connected to parallel resistors. A difference resistor drives an inverting input of an op amp that drives a transistor that generates the bandgap reference voltage Vbg. A sensing resistor connects Vbg to a splitting node that connects to the non-inverting input through a first parallel resistor. The splitting node also connects through a second parallel resistor to the inverting input. Fuses or switches enable the trimming-up and trimming-down resistors. The trimming-up resistors are in series with the sensing resistor and the trimming-down resistors are in series with an output resistor that connects Vbg to reference voltage Vref. The circuit can be designed for a more typical process since bi-directional trimming allows Vref to be raised or lowered. Many circuits need no trimming when targeted for the typical process.

Bi-directional trimming methods and circuits for a precise band-gap reference

A power converter has a power transistor driving a power current through an inductor to provide a controlled power-supply voltage. The power transistor is on during a first state but off during a second state when a sink transistor reduces the power current through the inductor. Both voltage sensing of the power-supply voltage and current sensing at the power transistor provide feedback to control the amount of time that the first state is active, and thus control the power current. Current sensing is provided by a smaller minor transistor in parallel with the power transistor. The minor transistor turns on after the power transistor to reduce disturbance spikes. Switches connect sources of the power and mirror transistors to an amplifier that drives a sensing transistor. The sensing transistor generates a sensing voltage from the mirror transistor source. During the second state the amplifier's inputs are equalized to provide fast response.

Current-mode-controlled current sensor circuit for power switching converter

Growing community of inventors

Hangzhou, China

Xiao Fei Kuang