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The following articles examines sustainability issues regarding the following article: " Turn A Compensated Current Sink Into A Common Emitter (CE) Amplifier" Bill Reeve, // Electronic Design //, October 8, 2009 [|Article Link]

**Background:** The following design idea considers a design of a compensated current sink and builds upon it to produce a compensated CE amplifier. Having a temperature insensitive CE amplifier allows for more efficient operation of various circuit designs. Operation for the current sink operates in the following manner. A voltage reference at the base of transistor Q1 sets the same voltage across R4 due to the error amplifier configuration. This sets the current through the collector of Q3, hence outputting a desired current. The feedback between transistors Q2 and Q3 demonstrate the compensation abilities, namely temperature and forward gain (beta). The proposed addition of the bypass capacitors and load resistor turn the circuit into a compensated common-emitter (CE) amplifier. Though the topic of sustainability usually refers to the global effects on a large scale bases, many little devices and chips are overlooked. As "Sustainability describes a condition in which natural systems and social systems survive and thrive together indefinitely"[1], we will discuss the role of the BJTs in the system for a compensated CE amplifier and attempt to distinguish green engineering principles as they aim to "meet the needs of the present without compromising the ability of future generations to meet their own needs"[2].  **Energy:** Moore's Law states that the number of transistors on a chip will double about every two years [3]. As a result, the processing power required to run all of the transistors in a computer have increased as well. As the power consumption of computer nodes double every 18 months, the sustainability factor of transistors decrease over time. Since there is no sign of technology slowing down in adding the number of transistors per chip, a possible solution to the power efficiency considers looking at creating efficient circuits that outperform old designs. A recent article in 2009 examines the topic of predicting a newer, more efficient transistor material. Theorists at Stanford's Institute for Materials and Energy Science at SLAC National Accelerator Laboratory demonstrate a new material that exhibits the quantum spin Hall Effect. " In this exotic state of matter, electrons flow without dissipating heat, meaning a transistor made of the material would be drastically more efficient than anything available today. "[4]
 * Environment:** As CE amplifiers and current sinks are commonly used in all electronic design products, these products eventually become waste and get thrown away. Consumers generally update their current products by buying a new one and getting rid of their old devices. For example, approximately 130,000 computers and 100 million cell phones get thrown out in the U.S. each year[5]. The more electronic waste is dumped on the earth's surface, the faster our world will deteriorate due to the lead, cadmium, mercury, and other toxic materials that come from computers. Not only do the toxic materials harm the earth's surface but the humans as well because of the possible brain damage and cancer that results. An alternative to throwing away electronic equipment in our regular trash cans is to use electronic recycling. This method allows the chips in old computer devices to be reused in other products, saving money and reducing materials.


 * Economics:** From a design standpoint, Moore's Law allows transistors and other components to be placed on smaller ICs. Generally, IC's are inexpensive, will become cheaper to produce, and less can be made for a product as technology advances. As for the proposed design idea, only few companies and buyers will turn to the compensated CE amplifier for their own designs. Largely, many companies do not require the high accuracy measurement that the circuit design offers, but will most likely stick to an easier design. However, it is important to note again the electronic waste that this design can offer. Simple current sinks and amplifiers are used in such a variety of electronic devices that the components make for great recycling benefits.

 Green Engineering Design Principles: >  "This architecture is useful for building stable and device-tolerant BJT Class A amplifiers. "[6] The temperature and beta compensation of the circuit gives the chance to test the functionality using low level transistors that may not be as high quality, while maintaining the circuit's main functionality.  > Reduces production of future components through electronic recycling as the circuits are easily implementable on other products. Taking supplies from the natural ecosystem will decrease as reusable devices are produced. > Discussion of the simple circuit promotes electronic waste as CE amplifiers can be used for other new various devices as old ones are recycled. > Maximizing the output swing of the circuit through setting resistor value R5 ensures a safe output. The improvement of the transistors stated in Energy section through Stanford's theorists further ensures safe design implementation. > The proposed CE compensation builds on a previous design, adding only a few extra components. This allows for 2 differently functioning circuits with only a few extra components for the second function. > The usability of the circuit proves useful in various applications, thus reducing the amount of waste thrown out after the lifespan of a product. > The usability of the design considers a full implementation on to any device requiring CE amplification or Current Sinks. Since used throughout many products, the design is easily accessible to various consumers. > Creates a higher level design through testing for sensitivities with the transistors forward current gain (beta) as well as temperature measurements. Improves on a previous current sink design, reducing number of necessary components. > Further proposes ideas to electronic designers as they note the compensation factors in addition to usability and the fact that the circuit builds on a previous circuit.  References > Bill Reeve, // Electronic Design //, October 8, 2009, [] 
 * Equity:** Though the application for the design idea gears towards high accuracy specifications, such as military-grade equipment, the design process proves useful in consumer electronic applications as it demonstrates the topics of using feedback and voltage references with transistors. Direct stakeholders can benefit from production of these chips if there were a chance where high requirements of a product were set. Indirect stakeholders, such as military or government officials, have no problem financing for their devices as the application proves useful to them.
 * 1) Engineer processes and products holistically, use systems analysis, and integrate environmental impact assessment tools.
 * 1) <span style="color: black; line-height: normal; mso-list: l0 level1 lfo1; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list .5in;"><span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Conserve and improve natural ecosystems while protecting human health and well-being.
 * 1) <span style="color: black; line-height: normal; mso-list: l0 level1 lfo1; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list .5in;"><span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Use life-cycle thinking in all engineering activities.
 * 1) <span style="color: black; line-height: normal; mso-list: l0 level1 lfo1; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list .5in;"><span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Ensure that all material and energy inputs and outputs are as inherently safe and benign as possible.
 * 1) <span style="color: black; line-height: normal; mso-list: l0 level1 lfo1; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list .5in;"><span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Minimize depletion of natural resources.
 * 1) <span style="color: black; line-height: normal; mso-list: l0 level1 lfo1; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list .5in;"><span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Strive to prevent waste.
 * 1) <span style="color: black; line-height: normal; mso-list: l0 level1 lfo1; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list .5in;"><span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Develop and apply engineering solutions, while being cognizant of local geography, aspirations, and cultures.
 * 1) <span style="color: black; line-height: normal; mso-list: l0 level1 lfo1; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list .5in;"><span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Create engineering solutions beyond current or dominant technologies; improve, innovate, and invent (technologies) to achieve sustainability.
 * 1) <span style="color: black; line-height: normal; mso-list: l0 level1 lfo1; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list .5in;"><span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Actively engage communities and stakeholders in development of engineering solutions.
 * 1) <span style="line-height: normal; mso-list: l1 level1 lfo2; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list .5in;"><span style="font-family: 'Times New Roman',serif; font-size: 12pt;">S. R. Euston and W. E. Gibson, “The Ethic of Sustainability,” //Earth Ethics// **6**, 1995 p. 5-7. Available: [] . [Accessed Jan. 16, 2009].
 * 2) <span style="line-height: normal; mso-list: l1 level1 lfo2; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list .5in;"><span style="font-family: 'Times New Roman',serif; font-size: 12pt;">The World Commission on Environment and Development, //Our Common Future//, chaired by Norwegian Prime-Minister Gro Harlem Brundtland, 1987.
 * 3) <span style="line-height: normal; mso-list: l1 level1 lfo2; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list .5in;"><span style="font-family: 'Times New Roman',serif; font-size: 12pt;">Moore's Law, <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt;"> []  <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">
 * 4) <span style="line-height: normal; mso-list: l1 level1 lfo2; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list .5in;"> <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt;">[4] L. Schenkman, “Super-Efficient Transistor Material Predicted,” Physorg, May 15, 2009. Available: <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt;"> [] . [Accessed Nov. 14, 2010] <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">
 * 5) <span style="line-height: normal; mso-list: l1 level1 lfo2; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list .5in;"> <span style="border-bottom-color: windowtext; border-bottom-style: none; border-bottom-width: 1pt; border-left-color: windowtext; border-left-style: none; border-left-width: 1pt; border-right-color: windowtext; border-right-style: none; border-right-width: 1pt; border-top-color: windowtext; border-top-style: none; border-top-width: 1pt; font-family: 'Times New Roman',serif; font-size: 12pt; padding-bottom: 0in; padding-left: 0in; padding-right: 0in; padding-top: 0in;">[1]  <span style="font-family: "Times New Roman","serif"; font-size: 12.0pt;">Solly Granatstein. “Following The Trail Of Toxic E-Waste”. CBS, November 9, 2008, [Accessed: April 28, 2009] available: []  <span style="font-family: 'Times New Roman',serif; font-size: 12pt;">
 * 6) <span style="line-height: normal; mso-list: l1 level1 lfo2; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list .5in;"><span style="font-family: "Times New Roman","serif"; font-size: 12.0pt;">" Turn A Compensated Current Sink Into A Common Emitter (CE) Amplifier"