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{| class="toccolours" border="1" style="float: right; clear: right; margin: 0 0 1em 1em; border-collapse: collapse;" cellpadding=3
In electronics, the '''[[Miller effect]]''' is the increase in the equivalent input capacitance of an inverting voltage amplifier due to a capacitance connected between two gain-related nodes, one on the input side of an amplifier and the other the output side. The amplified input capacitance due to the Miller effect, called the '''Miller capacitance''' ''C<sub>M</sub>'', is given by
! colspan="7" align="center" style="background:#cccccc;"| Specific heat ratio of various gases
:<math>C_{M}=C (1-A)\ ,</math>
|-
where ''A''  is the voltage gain between the two nodes at either end of the coupling capacitance, which is a negative number because the amplifier is ''inverting'', and ''C'' is the coupling capacitance.
| bgcolor="#E0E0E0" align="center" | Gas
| bgcolor="#E0E0E0" align="center" | °C
| bgcolor="#E0E0E0" align="center" | '''''k'''''
| bgcolor="#E0E0E0" width="2" rowspan="17"| &nbsp;
| bgcolor="#E0E0E0" align="center" | Gas
| bgcolor="#E0E0E0" align="center" | °C
| bgcolor="#E0E0E0" align="center" | '''''k'''''
|-
| rowspan="7" align="center" | H<sub>2</sub>
| align="center" |−181
| 1.597
| rowspan="4" align="center" | Dry<BR>Air
| align="center" |20
| 1.40
|-
| align="center" |−76
| 1.453
| align="center" |100
| 1.401
|-
| align="center" |20
| 1.41
| align="center" |200
| 1.398
|-
| align="center" |100
| 1.404
| align="center" |400
| 1.393
|-
| align="center" |400
| 1.387
| rowspan="4" align="center" | CO<sub>2</sub>
| align="center" |0
| 1.310
|-
| align="center" |1000
| 1.358
| align="center" |20
| 1.30
|-
| align="center" |2000
| 1.318
| align="center" |100
| 1.281
|-
| align="center" | He
| align="center" |20
| 1.66
| align="center" |400
| 1.235
|-
|rowspan="2" align="center"|N<sub>2</sub>
| align="center" |−181
| 1.47
| align="center" |NH<sub>3</sub>
| align="center" |15
| 1.310
|-
| align="center" |15
| 1.404
| align="center" | CO
| align="center" |20
| 1.40
|-
| align="center"|Cl<sub>2</sub>
| align="center" |20
| 1.34
| rowspan="6" align="center" | O<sub>2</sub>
| align="center" |−181
| 1.45
|-
| rowspan="2" align="center" | Ar
| align="center" |−180
| 1.76
| align="center" |−76
| 1.415
|-
| align="center" |20
| 1.67
| align="center" |20
| 1.40
|-
| rowspan="3" align="center" | CH<sub>4</sub>
| align="center" |−115
| 1.41
| align="center" |100
| 1.399
|-
| align="center" |−74
| 1.35
| align="center" |200
| 1.397
|-
| align="center" |20
| 1.32
| align="center" |400
| 1.394
|}


The '''[[specific heat ratio]]''' of a gas is the ratio of the specific heat at constant pressure, <math>C_p</math>, to the specific heat at constant volume, <math>C_v</math>. It is sometimes  referred to as the '''adiabatic index''' or the '''heat capacity ratio''' or the '''isentropic expansion factor''' or the '''adiabatic exponent''' or the '''isentropic exponent'''.
Although the term ''Miller effect'' normally refers to capacitance, the Miller effect applies to any impedance connected between two nodes exhibiting gain. These properties of the Miller effect are generalized in '''Miller's theorem'''.


Either <math>\kappa</math> (kappa), <math>k</math> (Roman letter k) or <math>\gamma</math> (gamma) may be used to denote the specific heat ratio:
The Miller effect is named after John Milton Miller.<ref name=Miller/> When Miller published his work in 1920, he was working on vacuum tube triodes, however the same theory applies to more modern devices such as bipolar transistors and MOSFETs.
 
...
:<math>\kappa = k = \gamma = \frac{C_p}{C_v}</math>
 
where:
 
:<math>C</math> = the specific heat of a gas
:<math>p</math> = refers to constant pressure conditions
:<math>v</math> = refers to constant volume conditions
<BR><BR>

Revision as of 01:08, 11 June 2011

In electronics, the Miller effect is the increase in the equivalent input capacitance of an inverting voltage amplifier due to a capacitance connected between two gain-related nodes, one on the input side of an amplifier and the other the output side. The amplified input capacitance due to the Miller effect, called the Miller capacitance CM, is given by

where A is the voltage gain between the two nodes at either end of the coupling capacitance, which is a negative number because the amplifier is inverting, and C is the coupling capacitance.

Although the term Miller effect normally refers to capacitance, the Miller effect applies to any impedance connected between two nodes exhibiting gain. These properties of the Miller effect are generalized in Miller's theorem.

The Miller effect is named after John Milton Miller.[1] When Miller published his work in 1920, he was working on vacuum tube triodes, however the same theory applies to more modern devices such as bipolar transistors and MOSFETs. ...

  1. Cite error: Invalid <ref> tag; no text was provided for refs named Miller