A Low-Noise Fast-Transient-Response Delta-Sigma-Modulation Buck Converter With Hysteresis-Voltage-Controlled Techniques

A low-noise fast-transient-response second-order delta-sigma-modulation buck converter with hysteresis-voltage-controlled techniques is proposed. With the proposed control approach, the transient time can be accelerated by roughly 60%. The rail-to-rail OTA generates a current I
_Sense
, which replicates the inductor current I
_L
with K times. As ISense flows through the capacitor C
_Sense
, it will be converted into VSense. Then, the hysteresis-voltage-controlled (HVC) circuit compares the two terminal voltages of hysteresis comparator to detect the overshoot and undershoot of V
_Sense
. Once V
_Sense
is detected, the output signal of HVC circuits becomes opposite to the previous state to conduct M
_P
and M
_N
previously. Besides, the 2
^nd
-order delta-sigma-modulation (DSM) circuit plays a vital role of mitigating noise-interference and elevating noise in whole circuits. The proposed converter has been fabricated in TSMC
$0.18~\mu \text{m}$
1P6M CMOS processes with an active area of
$1.19\times 1.09$
mm
²
. The measured results show the transient time are
$3.5~\mu \text{s}$
and
$3.2~\mu \text{s}$
, respectively, when the load current changes between 500mA and 100mA. On the basic of the measured results of fast-fourier-transform (FFT), the value of output-to-noise ratio (ONR) is 76.6dB at the sampling frequency of 10MHz. The peak conversion efficiency is 92.1% while the load current is 300mA.