In electronics, gain is a measure of the ability of a circuit (often an amplifier) to increase the power or amplitude of a signal from the input to the output. It is usually defined as the mean ratio of the signal output of a system to the signal input of the same system. It may also be defined on a logarithmic scale, in terms of the decimal logarithm of the same ratio ("dB gain"). A gain greater than one (zero dB), that is, amplification, is the defining property of an active component or circuit, while a passive circuit will have a gain of less than one.

Thus, the term gain on its own is ambiguous. For example, "a gain of five" may imply that either the voltage, current or the power is increased by a factor of five, although most often this will mean a voltage gain of five for audio and general purpose amplifiers, especially operational amplifiers, but a power gain for radio frequency amplifiers, and for directional aerials will refer to a signal power change compared with a simple dipole. Furthermore, the term gain is also applied in systems such as sensors where the input and output have different units; in such cases the gain units must be specified, as in "5 microvolts per photon" for the responsivity of a photosensor. The "gain" of a bipolar transistor normally refers to forward current transfer ratio, either h_FE ("Beta", the static ratio of I_c divided by I_b at some operating point), or sometimes h_fe (the small-signal current gain, the slope of the graph of I_c against I_b at a point).

In laser physics, gain may refer to the increment of power along the beam propagation in a gain medium, and its dimension is m⁻¹ (inverse meter) or 1/meter.

Logarithmic units and decibels[link]

Power gain[link]

Power gain, in decibels (dB), is defined by the 10 log rule as follows:

Failed to parse (Missing texvc executable; please see math/README to configure.): \text{Gain}=10 \log \left( {\frac{P_{\mathrm{out}}}{P_{\mathrm{in}}}}\right)\ \mathrm{dB}

where P_in and P_out are the input and output powers respectively.

A similar calculation can be done using a natural logarithm instead of a decimal logarithm, and without the factor of 10, resulting in nepers instead of decibels:

Failed to parse (Missing texvc executable; please see math/README to configure.): \text{Gain} = \ln\left( {\frac{P_{\mathrm{out}}}{P_{\mathrm{in}}}}\right)\, \mathrm{Np}

Voltage gain[link]

When power gain is calculated using voltage instead of power, making the substitution (P=V ²/R), the formula is:

Failed to parse (Missing texvc executable; please see math/README to configure.): \text{Gain}=10 \log{\frac{(\frac{{V_\mathrm{out}}^2}{R_\mathrm{out}})}{(\frac{{V_\mathrm{in}}^2}{R_\mathrm{in}})}}\ \mathrm{dB}

In many cases, the input and output impedances are equal, so the above equation can be simplified to:

Failed to parse (Missing texvc executable; please see math/README to configure.): \text{Gain}=10 \log \left( {\frac{V_\mathrm{out}}{V_\mathrm{in}}} \right)^2\ \mathrm{dB}

and then the 20 log rule:

Failed to parse (Missing texvc executable; please see math/README to configure.): \text{Gain}=20 \log \left( {\frac{V_\mathrm{out}}{V_\mathrm{in}}} \right)\ \mathrm{dB}

This simplified formula is used to calculate a voltage gain in decibels, and is equivalent to a power gain only if the impedances at input and output are equal.

Current gain[link]

In the same way, when power gain is calculated using current instead of power, making the substitution (P = I ²R), the formula is:

Failed to parse (Missing texvc executable; please see math/README to configure.): \text{Gain}=10 \log { \left( \frac { {I_\mathrm{out}}^2 R_\mathrm{out}} { {I_\mathrm{in}}^2 R_\mathrm{in} } \right) } \ \mathrm{dB}

In many cases, the input and output impedances are equal, so the above equation can be simplified to:

Failed to parse (Missing texvc executable; please see math/README to configure.): \text{Gain}=10 \log \left( {\frac{I_\mathrm{out}}{I_\mathrm{in}}} \right)^2\ \mathrm{dB}

and then:

Failed to parse (Missing texvc executable; please see math/README to configure.): \text{Gain}=20 \log \left( {\frac{I_\mathrm{out}}{I_\mathrm{in}}} \right)\ \mathrm{dB}

This simplified formula is used to calculate a current gain in decibels, and is equivalent to the power gain only if the impedances at input and output are equal.

The "current gain" of a bipolar transistor, h_FE or h_fe, is normally given as a dimensionless number, the ratio of I_c to I_b (or slope of the I_c-versus-I_b graph, for h_fe).

In the cases above, gain will be a dimensionless quantity, as it is the ratio of like units (Decibels are not used as units, but rather as a method of indicating a logarithmic relationship). In the bipolar transistor example it is the ratio of the output current to the input current, both measured in Amperes. In the case of other devices, the gain will have a value in SI units. Such is the case with the operational transconductance amplifier, which has an open-loop gain (transconductance) in Siemens (mhos), because the gain is a ratio of the output current to the input voltage.

Example[link]

Q. An amplifier has an input impedance of 50 ohms and drives a load of 50 ohms. When its input (Failed to parse (Missing texvc executable; please see math/README to configure.): V_\mathrm{in} ) is 1 volt, its output (Failed to parse (Missing texvc executable; please see math/README to configure.): V_\mathrm{out} ) is 10 volts. What is its voltage and power gain?

A. Voltage gain is simply:

Failed to parse (Missing texvc executable; please see math/README to configure.): \frac{V_\mathrm{out}}{V_\mathrm{in}}=\frac{10}{1}=10\ \mathrm{V/V}.

The units V/V are optional, but make it clear that this figure is a voltage gain and not a power gain. Using the expression for power, P = V²/R, the power gain is:

Failed to parse (Missing texvc executable; please see math/README to configure.): \frac{V_\mathrm{out}^2/50}{V_\mathrm{in}^2/50} = \frac{V_\mathrm{out}^2}{V_\mathrm{in}^2}=\frac{10^2}{1^2}=100\ \mathrm{W/W}.

Again, the units W/W are optional. Power gain is more usually expressed in decibels, thus:

Failed to parse (Missing texvc executable; please see math/README to configure.): G_{dB}=10 \log G_{W/W}=10 \log 100=10 \times 2=20\ \mathrm{dB}.

A gain of factor 1 (equivalent to 0 dB) where both input and output are at the same voltage level and impedance is also known as unity gain.

See also[link]

• Active laser medium
• Antenna gain
• Aperture-to-medium coupling loss
• Automatic gain control
• Attenuation
• Complex gain
• DC offset
• Effective radiated power
• Gain before feedback
• Insertion gain
• Loop gain
• Open-loop gain
• Net gain
• Power gain
• Process gain
• Transmitter power output

 This article incorporates public domain material from the General Services Administration document "Federal Standard 1037C".

Jo Kwon
Background information
Birth name	Jo Kwon (조권)
Born	(1989-08-28) August 28, 1989 (age 22) Suwon, Gyeonggi Province, South Korea
Occupations	Singer, dancer, entertainer, actor, MC
Instruments	Vocal, piano
Years active	2008–present
Labels	JYP Entertainment
Associated acts	2AM 2PM

Jo Kwon (Hangul: 조권, born August 28, 1989) is a South Korean singer and entertainer, leader of ballad boyband 2AM.

Predebut[link]

Jo Kwon, commonly known as Sacre Bleu, is the longest-serving male trainee in JYP Entertainment, having trained for 2567 days; exactly 7 years and 12 days since joining JYP. He was chosen as the last members of Park Jin Young's "99% Challenge Project" along with Sunye of Wonder Girls.^{[citation needed]}

In 2008, he appeared on MNET's Hot blood, a program that showed the intense physical training that 13 male trainees had to go through for the opportunity to debut in either 4-member ballad group or 7-member dance group One Day under JYP Entertainment.^[1] After getting through the eliminations, Jo Kwon was given the position of 4-member ballad group's leader.He has been attending Kyung Hee University.^[2]

Debut[link]

2AM's first single "This Song" release July 21, 2008 and made their debut performance on July 11, 2008 performing "이 노래" ("This Song").^[3]

Solo Contributions[link]

Television[link]

Jo Kwon regularly appears as a regular guest on variety shows such as "Star King", popular for his playful and frivolous dance gags. He was part of "Dirty Eyed Girls" on an episode of 2PM's variety show "Wild Bunny", performing a parody of popular Brown Eyed Girls song Abracadabra. The music video became extremely popular.^[4] In September 2009, Jo Kwon was one of the main MCs for SBS's environmental variety show "Find it! Green Gold" with Super Junior member Shindong, SS501 member Kim Hyung Joon, and former Fly To The Sky member Brian Joo. He also replaced Jaebeom on historical culture variety show Nodaji after his internet controversy.^[5] Both shows were later canceled due to low ratings.^{[citation needed]}

He joined the cast of We Got Married on October 3, 2009, coupled up with Brown Eyed Girls member Ga-In. Although they were initially only supposed to feature for the Chuseok special, their appearance brought in the highest ratings yet for Season II, and they were announced a permanent couple.^[6] Jo Kwon was diagnosed with H1N1 on October 28, 2009, causing him to postpone filming We Got Married. The next day, a representative stated that Jo Kwon was recovering quickly after treatment.^{[citation needed]}

In 2010, he became a permanent cast member of Family Outing 2.^[7] He is also currently acting in the sitcom All My Love with co stars Park Min Sun, Kim Gab Soo and fellow idol and 'wife' Ga-In from Brown Eyed Girls.

Music[link]

He sang with Jinwoon in May Doni's "몰라-ing" ("Molla-ing"), as well as a duet with Changmin titled "졸업" ("Graduation") on February 5, 2009, and Baek Jiyoung's "밤새도록" ("All Night") on her 7th album Sensibility. He featured in Lee Seung Hwan's Special Album "Hwantastic" with the song "덩크슛" ("Dunk Shoot") a duet with Whale (from W&Whale)and also featured in the music video in September 2009.^[8]

He released a digital single "우리 사랑하게 됐어요" ("We Fell in Love") on December 16, 2009, a duet with his We Got Married partner Ga-in.,^[9] which topped variety online music charts, winning 2 awards on Music Bank's K-Charts and the "Most Popular Background Phone Music" on the Gaon Charts.^[10] 50 million won from the profits of the song were donated to help out for Haiti's earthquake.^[11] For these efforts, Jo Kwon was given an award at the 3rd Korea Sharing Awards ceremony.^[12]

Jo Kwon participated in Wax's repackaged album Unplugged Side A. He sang a duet with her titled "이별이야기" ("Farewell Song"), released on March 24, 2010.^[13]

On June 30, 2010, Jo Kwon released his first solo digital single titled "고백하던 날" ("The Day I Confessed"), a song he partially composed during the We Got Married broadcast for Ga-in. The song reached No. 1 on Cyworld real time charts the day after its release.^[14]

Jo Kwon appeared on an episode of 2 pm Show along with a member of 2 am Seul Ong

Filmography[link]

• 2010 – Running Man (guest ep 7) – SBS
• 2010–2011 All My Love [( Ok Yeob)] -MBC

Awards[link]

References[link]

External links[link]

• Jo Kwon's Microblogging on Cyworld
• Jo Kwon on Twitter
• Jo Kwon on Me2day

This biographical article needs additional citations for verification. Please help by adding reliable sources. Contentious material about living persons that is unsourced or poorly sourced must be removed immediately, especially if potentially libelous or harmful. (April 2009)

This article may require cleanup to meet Wikipedia's quality standards. No cleanup reason has been specified. Please help improve this article if you can; the talk page may contain suggestions. (April 2009)

Park Jin-young
Jin Young in Bangkok, Thailand.
Background information
Birth name	Park Jin Young
Also known as	"The Asian Soul"
Born	(1972-01-13) January 13, 1972 (age 40)
Origin	Seoul, Korea[1]
Genres	K-pop, R&B
Occupations	singer, dancer, record producer, actor
Instruments	Singing
Years active	1994–Present
Labels	JYP Entertainment
Associated acts	JYP Nation

Park Jin-young (Hangul: 박진영, Hanja: 朴軫泳; born January 13, 1972), also known as J.Y. Park or JYP, is a singer, songwriter, dancer, actor, record producer and the former CEO and founder of JYP Entertainment, a major artist management/record label of Korean pop music. He is best known for his songs called “Don’t Leave Me”, “Elevator”, “She Was Pretty”, “Honey”, “Kiss”, “Your House”. He founded JYP Entertainment in 1997, composing and producing several singles and albums for various singers in South Korea including g.o.d., Park Ji-yoon, Rain, Byul, Wonder Girls, 2AM, 2PM, miss A, JJ Project

Biography[link]

Park was born in Seoul, Korea on January 13, 1972. He graduated from BaeMyung High School, and he earned his bachelor’s degree from Yonsei University.

Music career[link]

In 1992, Park debuted as a group called ‘Park Jin-Young and the New Generation,’ but it was not successful. In 1994, he debuted as a solo singer with the new album Blue City featured the song “Don’t Leave Me”, and it was successful.

Park has released seven albums. He followed Blue City with his second album Tantara in 1995. His third album Summer Jingle Bell came out in 1997 and featured the hit song "She Was Pretty". His fourth album Even After 10 Years (1998) featured the song "Honey", and his seventh album Back To Stage (2007) featured the song "Kiss". While maintaining his status as a successful artist, he has also composed and produced over 31 charting singles and 25 albums for various groups in South Korea including Rain and Wonder Girls.

Park also became the first Asian producer to successfully cross over to the U.S., producing music for Will Smith, Mase and Cassie.^{[citation needed]}

In May 2008, Park collaborated with Jackie Chan to form the "I Love Asia" Project, prompted by the earthquake tragedy in China. Park is a capable English speaker, as evidenced by the various interviews he has conducted in the U.S.^[2][3] Park also holds a B.A. in Geology from Yonsei University.^{[citation needed]}

In October 2009, JYP also became the first Korean songwriter together with Rainstone to enter the Billboard Hot 100 Chart with the Wonder Girls hit single 'Nobody' which debuted at 76.^[4]

On December 3, 2009, JYP released his single, No Love No More.^[5]

Acting[link]

In early 2011, JYP made his acting debut in Dream High, for which he received a nomination for New Actor of the Year at the Baek Sang Arts Awards. In January 2012 he was seen in the sequel to Dream High called Dream High 2. ^[6]

In 2012, Park made his film debut as Choi Young In, a man on a mission to hand-deliver 5 million dollars, in Five Million Dollar Man with Jo Sung-ha and Min Hyo-rin.^[7] The film was schedule for premiere on 28 June followed by a large-scale showcase on 30 June but had to be push back due to the delay of Lee Byung-hun's Hollywood sequel G.I. Joe: Retaliation from 29 June to 29 March 2013.^[8]

Business career[link]

Park decided to further expand JYP Entertainment by opening the JYP Manhattan Center in 2007 and the JYP Beijing Center in 2008. At the JYP Manhattan Center, he was training three singers for their American debut in 2010. However, he has postponed their debuts because of the recession.^[9] Min has since debuted with Miss A, J Lim has returned to Korea to pursue her career, and G-Soul is still waiting to debut.^[10] Every artist that has been managed by JYP has gone through the JYP Academy, a training system that includes intensive training in vocal, dance, acting, and language. JYP is currently in the development stages of producing a U.S. TV show with Lawrence Bender that will be based around the Wonder Girls.^[11]

Due to his success in helping to create Asian singers, he was invited to be keynote speaker at Midem 2009, a music conference that brings together over 9,000 professionals from over 90 different countries.^[12] In June 2009, JYP Entertainment and the Jonas group has signed the management deal for the Wonder Girls. Wonder Girls, a girl group that J.Y. Park produced, will be releasing an album and joining the tour with the band group Jonas Brothers.^[13]

Personal life[link]

Park Jin-young married his wife, Seo Yoon-jeong, in 1999. It was announced in March 2009 that the couple would be divorcing after 10 years of marriage.^[14] On the official JYP website, Park noted that although they have been together for 16 years, they grew apart and eventually decided to go their separate ways.^[15]

Discography[link]

Studio albums[link]

• 1994: Blue City
• 1995: Tantara
• 1997: Summer Jingle Bell
• 1998: Even After 10 Years
• 1998: Kiss Me
• 2001: Game
• 2007: Back To Stage

EP[link]

• 2009: Sad Freedom
• 2012: Spring - 5 Songs for 1 New Love

Filmography[link]

Television series[link]

• 2011: Dream High
• 2012: Dream High 2

Film[link]

• 2012: The Wonder Girls Movie
• 2012: Five Million Dollar Man

Awards[link]

• M.net Asian Music Awards, Best Asian Composer for Nobody (Wonder Girls song) (2009)
• Inaugurated by Korean President, Lee Myung-Bak as "Personal Advisor to the Future Planning Council"
• The 100 Most Influential Contributors of the Year (2007)
• Model Line's Best Dressed of the Year (2007)
• SBS Popular Song Grand Prize Producer of the Year Award (2002)
• Seoul Popular Song Grand Prize Composer of the Year Award (2001)
• KBS Popular Song Grand Prize Composer of the Year Award (2001)
• m.net music video Award (2001)
• Best Music Video Award (R&B category) (2001)
• SBS Popular Song Grand Prize Composer of the Year Award, Producer of the Year Award (2001)
• Seoul Popular Song Grand Prize Composer of the Year Award (2001)
• Daily Sports Popular Song Grand Prize Teen Singer of the Year Award (2001)
• SBS Popular Song Grand Prize Composer of the Year Award, Songwriter of the Year Award, Producer of the Year Award (2000)
• SBS Popular Song Grand Prize Composer of the Year Award (1999)
• SBS Popular Song Grand Prize Music Arrangement of the Year Award (1997)
• KBS Popular Song Grand Prize Singer in His Teens Award (1997)
• Model Line Selected '97 Best Dresser Award (1997)

References[link]

External links[link]

• JYP Entertainment - Official Webage (Korean)