Formal charge - Revision history

178.38.77.5: /* Examples */

2014-10-22T21:42:05Z

Examples

← Older revision		Revision as of 23:42, 22 October 2014
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	~~[[Image:Schaltskizze Elektromechanischer Zerhacker.svg\|thumb\|Schematic of an inverter using a [[vibrator (electronic)\|vibrator]] as a chopper.]]~~		The writer is called Irwin Wunder but it's not the most masucline title out there. Minnesota is where he's been living for years. To collect coins is a factor that I'm totally addicted to. For years I've been working as a payroll clerk.<br><br>Feel free to surf to my web blog :: at home std test ([http://moodle.Cephuelva.org/redesceps/user/view.php?id=800791&course=1 My Home Page])

	~~A '''chopper''' circuit is used to refer to numerous types of electronic switching devices and circuits.~~ The ~~term has become somewhat ill-defined, and as a result~~ is ~~much less used nowadays than~~ it ~~was perhaps 30 or more years ago.~~

	~~Essentially, a chopper is an electronic [[switch]] that is used to interrupt one signal under~~ the ~~control of another.~~
	~~Choppers may be classified on several bases.~~

	~~1. On basis of I/P-O/p voltage levels:~~
	~~i Step-down chopper~~
	~~ii. Step-up chopper~~

	~~2. On basis of direction of output voltage and current:~~
	~~i. Class A~~
	~~ii. Class B~~
	~~iii. Class C~~
	~~iv. Class D~~
	~~v. Class E~~

	~~3. On basis of circuit operation:~~

	i. ~~First quadrant~~
	~~ii. Two quadrant~~
	~~iii. Four quadrant~~

	~~4. On basis of commutation method:~~

	~~i. Voltage commutated~~
	~~ii. Current commutated~~
	~~iii. Load commutated~~
	~~iv. Impulse commutated~~

	~~Most modern uses also use alternative nomenclature which helps to clarify which particular type of circuit~~ is ~~being discussed. These include:~~

	* [[switched-mode power supply\|switched mode power supplies]], including [[DC to DC converter]]s.
	* Speed controllers for [[DC motor]]s
	* Class D [[Electronic amplifier]]s
	* [[Switched capacitor]] [[Electronic filter\|filter]]s
	* [[Variable Frequency Drive]]

	~~==Chopper amplifiers==~~
	~~{{Split section\|date=January 2013}}~~
	~~One classic use for a chopper circuit and~~ where the term is still in use is in '''chopper amplifiers'''. These are [[Direct current\|DC]] amplifiers. Some types of signals that need amplifying can be so small that an incredibly high [[gain]] is required, but very high gain DC amplifiers are much harder to build with low offset and 1/<math>f</math> noise, and reasonable stability and [[Bandwidth (signal processing)\|bandwidth]]. It's much easier to build an [[Alternating current\|AC]] amplifier instead. A chopper circuit is used to break up the input signal so that it can be processed as if it were an AC signal, then integrated back to a DC signal at the output. ~~In this way, extremely small DC signals can be amplified. This approach is often used in electronic instrumentation where stability and accuracy are essential; for example, it~~ is ~~possible using these techniques to construct [[pico-]]voltmeters and [[Hall effect sensor\|Hall sensor]]s.~~

	~~The [[input offset voltage]] of amplifiers becomes important when trying to amplify small signals with very high gain. Because this technique creates~~ a very low input offset voltage amplifier, and because this input offset voltage does not change much with time and temperature, these techniques are also called "Zero-Drift" amplifiers (because there is no drift in input offset voltage with time and temperature). Related techniques that ~~also give these Zero-drift advantages are Auto-zero and Chopper-stabilized Amplifier.~~

	~~Auto-zero amplifiers use a secondary auxiliary amplifier~~ to ~~correct the input offset voltage of a main amplifier~~. ~~Chopper-stabilized amplifiers use~~ a ~~combination of auto-zero and chopper techniques to give some excellent DC precision specifications~~.<~~ref~~>~~US Patent 7132883 - Chopper chopper-stabilized instrumentation and operational amplifiers~~<~~/ref~~>

	~~Some example chopper and auto-zero amplifiers are [http~~:~~//www.linear.com/product/LTC2050 LTC2050],[http~~:~~//www.maxim-ic.com/quick_view2.cfm/qv_pk/3407 MAX4238/MAX4239] and~~ [http://~~focus~~.ti.~~com~~/~~docs~~/~~prod~~/~~folders/print/opa333~~.~~html OPA333].~~

	~~==See also~~==
	* [[Instrumentation amplifier]]
	* [[Operational amplifier]]
	* [[Pulse-width modulation]]

	~~==References==~~
	~~<references/>~~
	*C. Enz, G. Temes, {{doi-inline\|10.1109/5.542410\|Circuit techniques for reducing the Effect of Op-Amp Imperfections: Autozeroing, Correlated Double Sampling and Chopper Stabilization}} - Proceedings of the [[IEEE]], vol. 84 No. 11, Nov. 1996
	*A. Bilotti, G. Monreal, ''Chopper-Stabilized Amplifiers with a Track-and-hold Signal Demodulator'' - Allegro Technical Paper STP 99-1
	*A. Bakker, K. Thiele, J. Huijsing, {{doi-inline\|10.1109/4.890300\|A CMOS Nested-Chopper Instrumentation Amplifier with 100-nV Offset}} - IEEE J. Solid-State Circuits, vol. 35 No. 12, Dec 2000

	~~[[Category:Electronic circuits]~~]

en>DanBever at 19:28, 26 November 2013

2013-11-26T19:28:55Z

← Older revision		Revision as of 21:28, 26 November 2013
Line 1:		Line 1:
	~~Hello~~ and ~~welcome~~. ~~My title~~ is ~~Irwin and I totally dig~~ that ~~name~~. ~~For years~~ I~~'ve been working as a payroll clerk~~. ~~To do aerobics~~ is a ~~thing~~ that I'~~m totally addicted~~ to. ~~South Dakota~~ is ~~exactly~~ where me and ~~my husband live~~ and ~~my family members loves it~~.<br><br>~~Feel free to visit my blog~~ - [http://www.~~pcguide~~.com/vb/~~member~~.~~php?125284~~-~~JArredond~~ http://~~www~~.~~pcguide~~.com/vb/~~member~~.~~php?125284~~-~~JArredond~~]		[[Image:Schaltskizze Elektromechanischer Zerhacker.svg\|thumb\|Schematic of an inverter using a [[vibrator (electronic)\|vibrator]] as a chopper.]]

			A '''chopper''' circuit is used to refer to numerous types of electronic switching devices and circuits. The term has become somewhat ill-defined, and as a result is much less used nowadays than it was perhaps 30 or more years ago.

			Essentially, a chopper is an electronic [[switch]] that is used to interrupt one signal under the control of another.
			Choppers may be classified on several bases.

			1. On basis of I/P-O/p voltage levels:
			i Step-down chopper
			ii. Step-up chopper

			2. On basis of direction of output voltage and current:
			i. Class A
			ii. Class B
			iii. Class C
			iv. Class D
			v. Class E

			3. On basis of circuit operation:

			i. First quadrant
			ii. Two quadrant
			iii. Four quadrant

			4. On basis of commutation method:

			i. Voltage commutated
			ii. Current commutated
			iii. Load commutated
			iv. Impulse commutated

			Most modern uses also use alternative nomenclature which helps to clarify which particular type of circuit is being discussed. These include:

			* [[switched-mode power supply\|switched mode power supplies]], including [[DC to DC converter]]s.
			* Speed controllers for [[DC motor]]s
			* Class D [[Electronic amplifier]]s
			* [[Switched capacitor]] [[Electronic filter\|filter]]s
			* [[Variable Frequency Drive]]

			==Chopper amplifiers==
			{{Split section\|date=January 2013}}
			One classic use for a chopper circuit and where the term is still in use is in '''chopper amplifiers'''. These are [[Direct current\|DC]] amplifiers. Some types of signals that need amplifying can be so small that an incredibly high [[gain]] is required, but very high gain DC amplifiers are much harder to build with low offset and 1/<math>f</math> noise, and reasonable stability and [[Bandwidth (signal processing)\|bandwidth]]. It's much easier to build an [[Alternating current\|AC]] amplifier instead. A chopper circuit is used to break up the input signal so that it can be processed as if it were an AC signal, then integrated back to a DC signal at the output. In this way, extremely small DC signals can be amplified. This approach is often used in electronic instrumentation where stability and accuracy are essential; for example, it is possible using these techniques to construct [[pico-]]voltmeters and [[Hall effect sensor\|Hall sensor]]s.

			The [[input offset voltage]] of amplifiers becomes important when trying to amplify small signals with very high gain. Because this technique creates a very low input offset voltage amplifier, and because this input offset voltage does not change much with time and temperature, these techniques are also called "Zero-Drift" amplifiers (because there is no drift in input offset voltage with time and temperature). Related techniques that also give these Zero-drift advantages are Auto-zero and Chopper-stabilized Amplifier.

			Auto-zero amplifiers use a secondary auxiliary amplifier to correct the input offset voltage of a main amplifier. Chopper-stabilized amplifiers use a combination of auto-zero and chopper techniques to give some excellent DC precision specifications.<ref>US Patent 7132883 - Chopper chopper-stabilized instrumentation and operational amplifiers</ref>

			Some example chopper and auto-zero amplifiers are [http://www.linear.com/product/LTC2050 LTC2050],[http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3407 MAX4238/MAX4239] and [http://focus.ti.com/docs/prod/folders/print/opa333.html OPA333].

			==See also==
			* [[Instrumentation amplifier]]
			* [[Operational amplifier]]
			* [[Pulse-width modulation]]

			==References==
			<references/>
			*C. Enz, G. Temes, {{doi-inline\|10.1109/5.542410\|Circuit techniques for reducing the Effect of Op-Amp Imperfections: Autozeroing, Correlated Double Sampling and Chopper Stabilization}} - Proceedings of the [[IEEE]], vol. 84 No. 11, Nov. 1996
			*A. Bilotti, G. Monreal, ''Chopper-Stabilized Amplifiers with a Track-and-hold Signal Demodulator'' - Allegro Technical Paper STP 99-1
			*A. Bakker, K. Thiele, J. Huijsing, {{doi-inline\|10.1109/4.890300\|A CMOS Nested-Chopper Instrumentation Amplifier with 100-nV Offset}} - IEEE J. Solid-State Circuits, vol. 35 No. 12, Dec 2000

			[[Category:Electronic circuits]]

69.61.153.122 at 19:43, 3 July 2012

2012-07-03T19:43:42Z

New page

Hello and welcome. My title is Irwin and I totally dig that name. For years I've been working as a payroll clerk. To do aerobics is a thing that I'm totally addicted to. South Dakota is exactly where me and my husband live and my family members loves it.<br><br>Feel free to visit my blog - [http://www.pcguide.com/vb/member.php?125284-JArredond http://www.pcguide.com/vb/member.php?125284-JArredond]