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The Design and Linearization of 60GHz Injection Locked Power Amplifier

Wang, Luhao LU (2016) EITM01 20122
Department of Electrical and Information Technology
Abstract
The RF power amplifier is one of the most critical blocks of transceivers, as it is expected to provide a suitable output power with high gain, efficiency and linearity.
In this paper, a 60-GHz power amplifier based on an injection locked structure is demonstrated in a standard 65 CMOS technology. The PA core consists of a cross-coupled pair of NMOS transistors with an NMOS current source. This structure can achieve large output power and high PAE, but with poor linearity performance. In order to improve the linearity, several linearization techniques are investigated, including adaptive biasing and predistortion. The results show that the adaptive biasing technique can enlarge the linear operation region, but results in poor AM-PM... (More)
The RF power amplifier is one of the most critical blocks of transceivers, as it is expected to provide a suitable output power with high gain, efficiency and linearity.
In this paper, a 60-GHz power amplifier based on an injection locked structure is demonstrated in a standard 65 CMOS technology. The PA core consists of a cross-coupled pair of NMOS transistors with an NMOS current source. This structure can achieve large output power and high PAE, but with poor linearity performance. In order to improve the linearity, several linearization techniques are investigated, including adaptive biasing and predistortion. The results show that the adaptive biasing technique can enlarge the linear operation region, but results in poor AM-PM performance. By instead using the predistortion technique, the AM-PM performance can be improved, but the linear region only extends slightly. Considering theses two techniques different advantages, we combine them together to improve not only the linear region but also the AM-PM performance.

Finally, a common source amplifier is added as the first stage. With proper bias, the linear operation region is then effectively extended by 7.3 dB. This two stage power amplifier achieves large output power, high linearity and high PAE simultaneously. It delivers a gain of 20dB, a Psat of 16.3dBm, a P1dB of 15.41dBm, and a PAE of 30%. (Less)
Popular Abstract
Since the invention of radio-frequency (RF) wireless communication more than 100 years ago, mobile phones and other wireless communications products for civilian consumption have developed rapidly. Nowadays, the demand for larger high data rate and capacities is rising sharply. The traditional wireless bandwidth is no longer able to meet some high-rate applications requirement. However, 60GHz wireless communication system is our solution, and up to 7 GHz unlicensed wide band around 60GHz is open to use across much of the world. Furthermore, the power amplifier (PA) is a critical part of any transmitter to convert the signal to higher power and drive the antenna. For power amplifiers, efficiency and linearity are most important. Power... (More)
Since the invention of radio-frequency (RF) wireless communication more than 100 years ago, mobile phones and other wireless communications products for civilian consumption have developed rapidly. Nowadays, the demand for larger high data rate and capacities is rising sharply. The traditional wireless bandwidth is no longer able to meet some high-rate applications requirement. However, 60GHz wireless communication system is our solution, and up to 7 GHz unlicensed wide band around 60GHz is open to use across much of the world. Furthermore, the power amplifier (PA) is a critical part of any transmitter to convert the signal to higher power and drive the antenna. For power amplifiers, efficiency and linearity are most important. Power amplifiers with low efficiency will result in high level of heat dissipation. Linearity is a measure of the signal distortion, which consists of gain compression (AM-AM distortion) and phase distortion (AM-PM distortion).

In this thesis work, an injection locked power amplifier is used to reduce the input driving requirements and improve the efficiency. Simulations have been performed for implementation in 65nm standard CMOS, which is a low-cost technology for fabrication of integrated circuits (chips). The injection locked technique means that a self-oscillating circuit is forced to run at the same frequency as the input signal. Furthermore, an integrated balun is added to transfer between single-ended and differential signals. The results show that this PA can achieve high efficiency but with poor linearity performance. In order to improve the linearity, different linearization techniques are investigated, including adaptive biasing and predistortion. Adaptive biasing is a feedback technique. At high output levels, the power amplifier has less gain, which leads to signal distortion. The adaptive biasing unit can sense the output power in real time and adjust the bias. The bias is then increased at increased output power in order to restore the power gain at high output levels. Predistortion is another linearization technique. A predistorter, which has a gain expansion characteristic, is then introduced before the PA to compensate for its gain reduction. Then, considering the advantages of these two linearization techniques, we combine them together to achieve even better results. Finally, a two-stage power amplifier is proposed by adding a common source amplifier as the first stage. The first stage can also produce a gain boost at the high output levels, and this expansion gain can be made to match the second-stage gain reduction very well. The simulation results show that the amplifier can achieve high linearity and efficiency at the same time. (Less)
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author
Wang, Luhao LU
supervisor
organization
course
EITM01 20122
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Power Amplifier, Injection-locking, Adaptive biasing, predistortion
report number
LU/LHT-EIT 2016-544
language
English
id
8894643
date added to LUP
2016-11-08 10:54:51
date last changed
2016-11-08 10:54:51
@misc{8894643,
  abstract     = {The RF power amplifier is one of the most critical blocks of transceivers, as it is expected to provide a suitable output power with high gain, efficiency and linearity.
In this paper, a 60-GHz power amplifier based on an injection locked structure is demonstrated in a standard 65 CMOS technology. The PA core consists of a cross-coupled pair of NMOS transistors with an NMOS current source. This structure can achieve large output power and high PAE, but with poor linearity performance. In order to improve the linearity, several linearization techniques are investigated, including adaptive biasing and predistortion. The results show that the adaptive biasing technique can enlarge the linear operation region, but results in poor AM-PM performance. By instead using the predistortion technique, the AM-PM performance can be improved, but the linear region only extends slightly. Considering theses two techniques different advantages, we combine them together to improve not only the linear region but also the AM-PM performance.

Finally, a common source amplifier is added as the first stage. With proper bias, the linear operation region is then effectively extended by 7.3 dB. This two stage power amplifier achieves large output power, high linearity and high PAE simultaneously. It delivers a gain of 20dB, a Psat of 16.3dBm, a P1dB of 15.41dBm, and a PAE of 30%.},
  author       = {Wang, Luhao},
  keyword      = {Power Amplifier,Injection-locking,Adaptive biasing,predistortion},
  language     = {eng},
  note         = {Student Paper},
  title        = {The Design and Linearization of 60GHz Injection Locked Power Amplifier},
  year         = {2016},
}