THESIS
2018
xiv, 62 pages : illustrations ; 30 cm
Abstract
With the proliferation of portable wireless applications and wireless sensor networks, such
as internet of things (IoT), wireless body area networks (WBANs), and Bluetooth low energy
(BLE), ultra-low-power (ULP) frontends have attracted a lot of attention. To maximize the
battery lifetime or to work with harvested energy, it is critical to minimize power consumption
and operate under ultra-low-voltage (ULV) supply.
The low noise amplifier (LNA) is the first active block in the RF front end, which needs to
provide impedance matching and sufficient gain, while maintaining low noise and high linearity.
All these requirements conflict with low power consumption and low voltage. As the CMOS
process is scaled to nanoscale, an ultra-low voltage design is more favorable, and it is one o...[
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With the proliferation of portable wireless applications and wireless sensor networks, such
as internet of things (IoT), wireless body area networks (WBANs), and Bluetooth low energy
(BLE), ultra-low-power (ULP) frontends have attracted a lot of attention. To maximize the
battery lifetime or to work with harvested energy, it is critical to minimize power consumption
and operate under ultra-low-voltage (ULV) supply.
The low noise amplifier (LNA) is the first active block in the RF front end, which needs to
provide impedance matching and sufficient gain, while maintaining low noise and high linearity.
All these requirements conflict with low power consumption and low voltage. As the CMOS
process is scaled to nanoscale, an ultra-low voltage design is more favorable, and it is one of
the methods to achieve low power consumption. However, an ultra-low voltage supply limits
the voltage swing and degrades the linearity performance of the LNA. A traditional LNA,
giving gain in the voltage mode, is not suitable for an ULV design. Alternatively, an LNA in
current mode or also known as a low noise trans-conductance amplifier (LNTA), followed by
a low impedance mixer, gives low voltage gain, converts voltage to current, and pushes the
current to voltage conversion to the baseband. In this case, no voltage gain is needed until it is
at the end of the baseband. Good linearity and low noise can be simultaneously satisfied
especially when a passive mixer is involved.
Recently, current reuse and trans-conductance (gm) boosting techniques are mostly used to
get low power consumption. By combining both techniques, power can be reduced further. So
a new current reuse 4-times-gm boosting LNTA is proposed. However, these techniques
sacrifice linearity of the front end. Thus, a linearization technique should be adopted.
Traditional linearization techniques either are unsuitable for low voltage application or have a
power penalty. The major components of nonlinearity of LNAs come from gm nonlinearity and
drain-source impedance. So a new linearization technique is also proposed, which cancels the
second and third nonlinear term of MOSFETS’ intrinsic gm at the same time, while drain-source
impedance nonlinearity is also taken into consideration by optimizing the loading
impedance of the LNTA.
The proposed LNTA is successfully integrated as part of a ULV ULP receiver for BLE, IoT
and WSN applications. It achieves a high input second order intercept point (IIP2) of 44.5 dBm
with 42 dB improvement and input third order intercept point (IIP3) of 16 dBm with 13 dB
improvement, and it achieves 3.2 dB NF, while only consuming 230 uW power with a 0.5 V
supply voltage.
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