لخّصلي

With the development of VLSI integrated circuits, SoC becomes more and more complex, which not only consists of transitional analog circuits, but also comprises registers, memory, and Digital Signal Processing (DSP) circuits.Since the power determines the operation duration of hearing-aid SoC and both supply voltage and volume voltage are 1 V, to minimize the power consumption and realize accurate control, a mixed-signal programmable TD-POR and volume control circuit based on SAR ADC for hearing-aid SoC is presented in this paper.The EOC signal of SAR ADC is used as the mode-change signal so that the circuit can detect the battery voltage and volume voltage alternately, which reduces both circuit size and total power consump-The zinc-air battery that supplies hearing-aid SoC has a large voltage variation from 1.4 V to 0.7 V. When supply voltage reaches or drops to the right threshold, to ensure the accurate power-on control and low-voltage warning,

the POR with ADC must be needed.DTPOR and DTBOR are the delay time to generate the POR and BOR pulse when the supply voltage reaches VPOR or drops under VBOR, respectively.The resistance and capacitance devices are affected by temperature, voltage, and other parameters in the process of integrated circuit, and the uncertainty of the delay time can be easily caused.So it can greatly affect the detection accuracy of the POR and BOR voltage that can hardly meet the high-resolution requirement.Transitional POR circuits are pure analog circuit that are based on delay cell and Schmitt Trigger [1-4].

With the development of VLSI integrated circuits, SoC
becomes more and more complex, which not only consists
of transitional analog circuits, but also comprises registers,
memory, and Digital Signal Processing (DSP) circuits. When
SoC is powered up, some of their internal nodes are with
intermediate metastable states. Therefore at the initial stage
of operation, a Power-On-Reset (POR) circuit is needed. The
POR signal should hold circuits in the reset state until the
power supply reaches a steady-state level when all the circuits
can operate correctly. And, in many applications, when
supply voltage suddenly drops, the SoC may malfunction. The
POR circuit also needs to generate a brown-out reset (BOR)
signal for warning or reset. The parameter definition of POR
and BOR is shown in Figure 1.
𝑉POR and 𝑉BOR are POR and BOR thresholds, respectively,
which determine the system to enter or leave the stable state.
DTPOR and DTBOR are the delay time to generate the POR and
BOR pulse when the supply voltage reaches 𝑉POR or drops
under 𝑉BOR, respectively. DTPOR and DTBOR must be set
long enough to confirm all the modules have entered steady
or reset state. 𝑇BOR and 𝑇POR are the POR and BOR pulse
width. As long as the DTPOR and DTBOR meet the system
specification, 𝑇POR and 𝑇BOR have no specific requirements.
Transitional POR circuits are pure analog circuit that are
based on delay cell and Schmitt Trigger [1–4]. Delay time is
set by resistor and capacitor of delay cell occupying large chip
area. The resistance and capacitance devices are affected by
temperature, voltage, and other parameters in the process of
integrated circuit, and the uncertainty of the delay time can
be easily caused. At the same time, the fixed POR and BOR
threshold are generated by the bandgap-based reference,
which has a large temperature drift. So it can greatly affect
the detection accuracy of the POR and BOR voltage that can
hardly meet the high-resolution requirement.
The zinc-air battery that supplies hearing-aid SoC has
a large voltage variation from 1.4 V to 0.7 V. When supply
voltage reaches or drops to the right threshold, to ensure
the accurate power-on control and low-voltage warning,

the POR with ADC must be needed. Moreover 𝑉POR and
𝑉BOR as well as DTPOR and DTBOR should be programmable
due to battery characteristic. Meanwhile the customers may
adjust the volume of hearing-aid device according to the
environment and their hearing condition. And the volume
adjustment usually has 32 stages. For precision, an 8-bit ADC
with 256 quantized steps is used to divide the adjustment
stages. Since the power determines the operation duration of
hearing-aid SoC and both supply voltage and volume voltage
are 1 V, to minimize the power consumption and realize
accurate control, a mixed-signal programmable TD-POR and
volume control circuit based on SAR ADC for hearing-aid
SoC is presented in this paper. The EOC signal of SAR ADC
is used as the mode-change signal so that the circuit can
detect the battery voltage and volume voltage alternately,
which reduces both circuit size and total power consump-