• 沒有找到結果。

Conclusions and Future Works

Technology 0.18-m 1.8-V/3.3-V CMOS Process

4.2 Future Works

4.2.3 Design of Bi-Phase Stimulus Driver

Some studies revealed that unbalanced stimulus current may cause net charge to store in body and lead to destructive problems such as electrolysis, gazing, pH changing, and dissolution [31], [32]. In order to solve these problems, the design of bi-phase stimulus driver is required. There are two ways to transfer biphasic stimulus current.

The first way is to use both positive and negative power supplies with one electrode per stimulus site as shown in Fig. 4.4. The second way is to use only positive power supply

with two electrodes per stimulus site as shown in Fig. 4.5. biphasic stimulus current through one electrode per stimulus site.

Charge between two electrodes per stimulus site.

Using the second method to achieve the purpose of delivering biphasic stimulus current, we can just copy the output driver of this proposed stimulus driver and place it symmetrically to the original one as shown in fig. 4.6. An extra control signal is also required to achieve charge balance during the stimulation period.

VCC

GND

V2 V1

Ro

VDD (1.8 V)

VCC

GND RL

(Tissue)

V2' V1' Ro’

VDD (1.8 V) Phase 1

Phase 2

Fig. 4.6. The method to implement biphasic stimulus current by making a copy of the output driver and placing it symmetrically to the origin circuit.

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Vita

姓 名:李 易 儒

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