IEEE Solid-State Circuits Magazine - Summer 2016 - 69

Liquid Crystal Display Driver
A liquid crystal device (LCD) requires
two polarities of two positive voltages
and two negative voltages to apply
sufficiently high positive and negative
voltages to each liquid crystal element
to improve its lifetime, as shown in
Figure 14 [20]. A requirement for gate
oxide of the transistors is sustaining
a voltage of 18 V to fully turn on the
pass transistors, which is half in cases
without generating voltages with two
polarities. Otherwise, it would need
a high voltage such as 36 V. A singledriver IC generates these four different voltages with a supply current of
an order of 10-100 μA because of no
direct current to ground.

Light-Emitting Diode Driver
Another application is the light-emitting
diode (LED) driver. Figure 15 forms a
single-stage charge pump with a chip
capacitor to have a large current up
to 100 mA. From a Li-ion battery of
2.7 V min, some white LEDs connected
in parallel can lighten at up to 4 V [21].

VDD
VOUT

T1
X

RFID
Figure 17 illustrates an ac-dc power
receiver collecting the energy in

T2
T0

CVIB

(a)

15
10
5
0

0 0.2 0.4 0.6 0.8 1
X

(b)

(c)

Figure 18: Vibration energy harvesting.

D1
N1
Ca

Battery

N3
D3

Vibration Energy

Figure 19: A battery charger for vibration energy harvesting using a feedback charge
pump.

dc Energy Transducer
Photovoltaic
IPV

Earphone Driver
Figure 16 is an integrated Cockcroft-
Walton (CW) multiplier for an earphone driver [22]. Using 0.18-μm
CMOS without any HV devices, it is
mentioned that a six-stage multiplier
generates 6 V with VIN of 1.2 V. An output voltage of 6 V is used for an audio
driver with 400 μA drive capability.
Even though the area and power efficiency should not be minimal due to
the high sensitivity of the output current on the parasitic capacitance as
discussed in [1], it seems that there
is an application where no additional
HV process is prioritized rather than
the area and power.

VOUT/VDD

value for GV is 7-10 when the supply
voltage of NAND Flash is 3 V. The
load of the charge pump is capacitive
because Fowler-Nordheim tunneling
current is much lower than the displacement current.

VPV

Rectifying Multiplier
IOUT

VOUT

VS
Φ

Thermoelectric
ITEG

Load

VTEG

- A Low dc Voltage < 0.6 V
- Large Output Resistance of the Transducer
* Optimum Design of Multiplier with the Additional Constraints
Figure 20: A dc energy transducer system.

a radio wave that doesn't require any
power supply voltage source in radiofrequency identification (RFID) [23].
The input power from the antenna
varies in a wide range. To protect capacitors and transistors from a high
power input, a limiter is required. At

every odd number stage, the capacitor is connected with the ground,
and at every even number stage it is
connected with the common clock
line. In comparison with a two-phase
clock Dickson pump, the single clock
pump lowers the maximum attainable

IEEE SOLID-STATE CIRCUITS MAGAZINE

SU M M E R 2 0 16

Table of Contents for the Digital Edition of IEEE Solid-State Circuits Magazine - Summer 2016