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“Parametronics”- A New Way to Design Low Noise High Efficiency RF Microwave Front Ends

  • Hedayati, Maziar
Publication Date
Jan 01, 2022
eScholarship - University of California
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The objective of this research is to develop, characterize, and demonstrate novel parametric architectures capable of wideband operation while maintaining high gain and low noise performance. Parametric amplification is a process of RF-RF power conversion that was well studied in the 1950s and 1960s that analyzed the power flow into and out of a nonlinear reactive element under excitation at its different harmonic frequencies. One of the most famous conclusions is Manley-Rowe relation which describes harmonics, intermodulation, and how the energy transfer from one frequency to another frequency. Based on Manley-Rowe relation the energy transferred among different intermodulation can be configured to have different characteristics depending on the termination of intermodulation tons and harmonics. We will show, that there are three different modes available: double sideband upconverting mode, negative resistance mode, and single sideband upconverting mode.Based on the characteristics of each mode, we will design different parametric components by first developing a set of analytical models describing their achievable gain, noise figure, and efficiency. These models will provide a set of design tools to design and optimize different prototype circuits. The prototype circuits will then be used to prove the concept based on gain, bandwidth, efficiency, and noise performance.As the first design, we present a parametric downconverter that may be used in a mixer-first receiver front-end. In such a receiver, the first mixer should offer a satisfactory low noise figure (NF), high conversion gain (CG) to suppress the noise contribution of the next stages, and high linearity to avoid receiver saturation in the presence of interferences. Parametric mixers are known to offer parametric conversion gain for frequency upconversion with no fundamental noise penalty due to its parametric amplification nature. This work is the first experimental demonstration of a parametric downconverter that achieves positive gain and low noise figure. The proof-of-concept mixer with a center input frequency of 1.9 GHz and an output frequency of 1.45GHz is designed and implemented on PCB. The mixer achieves a measured peak conversion gain of 10 dB and a 1-dB compression point of +7 dBm. Furthermore, the fabricated mixer achieves a minimum noise figure of 2.8 dB over its bandwidth. The second design is a novel matching technique for receivers with electrically small antenna (ESA) so that the receiver can achieve low noise performance over a broad bandwidth. We propose to match an electrically small dipole directly to a parametric amplifier, without using any inductors as they are often of low-quality factors and their loss contributes additional noise to the receiver. The parametric amplifier operates in a time-varying fashion, driven by a higher RF frequency pump. It exhibits a high impedance, time-varying capacitive load to the ESA. Therefore, the low-frequency voltage output from the ESA is detected at the input of the parametric amplifier, being amplified and upconverted to the proximity of the pump frequency at the output with minimum contamination of noise in this process. The proof-of-concept, a parametric matching for an electrically small bowtie dipole of ka<1/2 is designed and implemented on PCB which demonstrates that with this novel matching strategy, a low noise performance can be obtained for an electrically small antenna over a wide bandwidth. The complete theory of parametric matching is also presented which has been validated with the nonlinear circuit simulation results. A parametric power amplifier (PPA) with a unique load-modulation characteristic different from any existing architecture to enhance back-off efficiency will be presented as another application of parametronics. The proposed technique enables the transmission of high peak-to-average-power ratio (PAPR) signals with high efficiency while maintaining excellent linearity. The analysis is conducted to explore the relationship between the proposed load modulation network (LMN) parameters and the performance of PA to achieve high back-off efficiency. Generalized design formulas of the LMN parameters are then introduced to study the total power-delivering efficiency. Aided by the proposed load network, load modulation for class B amplifier can be achieved at saturation, leading to maximized efficiency over extended power. Upon theoretical proof of these discoveries, PA with a center frequency 220 MHz RF-input is developed and implemented on PCB. The prototype achieves 32 dBm output power, 49%–53% of efficiency at peak power, and 49%–53% at 10-dB output back-off (OBO).

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