|
|
| Line 1: |
Line 1: |
| [[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]]
| |
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.
Feel free to surf to my web blog :: at home std test (My Home Page)