The work that we're undertaking this summer fine tunes the design and is replacing some major subsystems within our overall product. Monday, June 4, Capstone Project An electromyography hardware acquisition unit was designed using commodity components with a view towards future full-scale ASIC integration. The acquired signal was amplified differentially and then processed using a combination of a bandpass filter and a dual notch filter. The filters were implemented using eighth-order switch capacitor filters with a reference clock frequency of 20 kHz.
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The bandpass filters retained the salient electromyographic frequencies of 20 Hz to Hz. The notch filters were placed at the problematic 60 Hz and Hz powerline interference frequencies.
Distributed CMOS Bidirectional Amplifiers
The processed analog signals were digitized using an eight bit analog-to-digital converter and then further processed for frequency content within a microcontroller. Bluetooth was used to transfer data from the microcontroller to a variety of Bluetooth enabled hardware devices including smart phones and laptops.
Gesture recognition software implemented using support vector machines interpreted both the muscle activity intensity and the sequencing of muscle activation thereby providing gesture recognition. The DA 10 is adapted to receive a first input signal that is a baseband signal that has a frequency of less than about 30 kHz. An optional output terminal network 16 is made up of an output resistor Rout and an output capacitor Cout that are coupled in series between a first input 18 and a common node A voltage source Vdd for supplying power to the DA 10 is coupled between the output resistor Rout and the output capacitor Cout.
A plurality of amplifier sections 22 , 24 , and N can be made up of transconductance cells that are configured as cascode devices that generate relatively low amounts of noise while producing relatively high amounts of linear power in comparison to a common source transistor configuration alone. Each of the plurality of tapered gate periphery transconductance devices comprises an input gate and an input source and has a gate-to-source capacitance between the input gate and the input source. Moreover, the gate-to-source capacitance of each of the plurality of tapered gate periphery transconductance devices increases moving from the DA input IN to the first output FOUT.
In another embodiment, the gate-to-source capacitance of each of the plurality of tapered gate periphery transconductance devices decreases moving from the DA input IN to the first output FOUT. The plurality of amplifier section 22 , 24 , and N may comprise gallium nitride GaN devices to realize a GaN low noise distributed amplifier.
The first, second, and Nth cascode device configurations reduce junction heating of the first, second, and Nth common source transistors caused from self heating, while the first, second, and Nth common gate transistors allow for relatively higher voltage operation. Moreover, an output section 26 of the DA 10 includes as a low noise termination amplifier cell that may be configured as a low noise amplifier 28 that has input impedance that effectively provides a load for the input line having the first group of inductive elements As a result, of the output section 26 , a need for a relatively noisy input line termination resistor is eliminated.
In at least one embodiment of the DA 10 , the low noise amplifier 28 may be a relatively large periphery low impedance cascode stage coupled to a broadband low-loss input matching circuit MC The cascode amplifier is configured to have wideband input impedance which effectively provides an optimal input transmission line termination that results in wideband DA low noise figure and high linearity.
Further, the cascode transconductance device may comprise a large gate periphery for improving the termination of the input termination line.
Broadbanding and Linearization Techniques
The use of a cascode feedback amplifier as the last section of the distributed amplifier is only representative, and may be replaced by another topological configuration of an amplifier with similar input impedance, noise, and linearity characteristics across a desired band. It should be appreciated that the configuration of the last section of the DA is not limited to the last section, but may apply to any number of sections in a manner to terminate the input transmission line in a gradual impedance transformation.
This is illustrated in FIG. In this embodiment, each successive section employs increasing amounts of feedback and larger device periphery to distribute the terminating impedance s across the different sections of the distributed amplifier. It should be noted that the cascode feedback amplifier is only representative and may be replaced by an amplifier s whose characteristics provide desired input impedance, noise, and linearity performance appropriate for achieving the overall objectives of providing a terminating impedance for the input transmission line which allows lower noise and no degradation of linearity compared to a resistively terminated DA.
Localized feedback is provided in each amplifier section 22 through N and the output section 26 via a series resistor and capacitor coupled between the drain and the gate of each cascode device configuration. For example, a feedback resistor Rfb 1 and a feedback capacitor Cfb 1 provides localized feedback for amplifier section 22 , whereas a feedback resistor Rfb 2 and a feedback capacitor Cfb 2 provides localized feedback for amplifier section The input impedance of this wideband LNA is roughly 50 ohms and terminates the input transmission line of the DA 10 in order to provide overall low noise while not compromising linear output capability.
Integrated as the last section of the DA 10 , the output section 26 can provide a low noise input line termination without compromising the linearity of the feedback amplifier of the output section 26 as it contributes output power in an additive manner to the output of the DA In FET implementations, it may be advantageous to increase the device size in order to lower the input impedance of the amplifier so that it is easier to low noise match to 50 ohms across a broad bandwidth.
Additionally, in order to preserve the noise figure under high voltage operation, a cascode may be employed in the amplifier in order to distribute the thermal self-heating in a manner which results in lower junction temperature for the primary common-source transconductance device. The input line termination impedance provided by the DA 10 may be distributed among multiple sections which results in a predetermined wideband DA response.
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In at least one embodiment, it may be desirable to taper the impedance transformation along the input line having a first group of inductive elements 12 by adjusting device periphery or by using various multiple feedback sections. For example successive ones of the plurality of amplifier sections 22 , 24 , and N may comprise tapered active impedance circuits to provide a gradually tapered impedance transition. Moreover, selected ones of the plurality of amplifier sections 22 , 24 , and N each include increased feedback.
This comparison shows that the IP3 output of DA 10 may not significantly degrade the performance compared to the resistively terminated conventional DA approach. Further inspection of FIG. However, DA 10 has an advantage of providing both the low noise performance of the active load approach while maintaining the high linear output power of the conventional DA approach. Moreover, the use of cascode-based active cells combined with the DA approach will reduce the transistor self-heating and lower its junction temperature which enables simultaneous low noise and high linear output power under high voltage and current operation.
When combined with gallium nitride high electron mobility transistor GaN HEMT technology, operation from baseband frequencies to microwave frequencies may be obtained with sub-dB NF and multiple watts of linear output power in a monolithic approach. In particular, FIG. One application for the high dynamic range LNA capability afforded by the present disclosure can enable future software defined communication systems. Those skilled in the art will recognize improvements and modifications to the preferred embodiments of the present disclosure.
All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow. Effective date : Year of fee payment : 4. The present disclosure describes a distributed amplifier DA that includes active device cells within sections that are configured to provide an input gate termination that is conducive for relatively low noise and high linearity operation. A section adjacent to an output of the DA is configured to effectively terminate the impedance of an input transmission line of the DA.
In this manner, noise generated by a common source transistor of the cascode configuration is minimized. The transistors coupled in the cascode configuration may be fabricated using gallium nitride GaN technology to reduce physical size of the DA and to further reduce noise. SUMMARY The present disclosure relates to a distributed amplifier DA having a plurality of amplifier sections, such that each of the plurality of amplifier sections has an input gate and an output drain including a first plurality of inductive elements coupled in series between a DA input and a first output to form a first plurality of connection nodes.
What is claimed is: 1. A distributed amplifier DA comprising: a plurality of amplifier sections, such that each of the plurality of amplifier sections has an input gate and an output drain;. It is implemented in 0. Additional Product Features Number of Volumes.
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Distributed CMOS Bidirectional Amplifiers : Broadbanding and Linearization Techniques - iqegumybiwyf.ml
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