JPS5496345A - Variable gain amplifier - Google Patents

Variable gain amplifier

Info

Publication number
JPS5496345A
JPS5496345A JP274178A JP274178A JPS5496345A JP S5496345 A JPS5496345 A JP S5496345A JP 274178 A JP274178 A JP 274178A JP 274178 A JP274178 A JP 274178A JP S5496345 A JPS5496345 A JP S5496345A
Authority
JP
Japan
Prior art keywords
input
circuit
signal
constant current
gain control
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP274178A
Other languages
Japanese (ja)
Inventor
Hideo Nishijima
Isao Fukushima
Hiroyuki Kimura
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Ltd
Original Assignee
Hitachi Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
Priority to JP274178A priority Critical patent/JPS5496345A/en
Publication of JPS5496345A publication Critical patent/JPS5496345A/en
Pending legal-status Critical Current

Links

Abstract

PURPOSE: To avoid the output fluctuation and occurrence of distortion even to the excessive input by constituting the emitter current source of the emitter-earthed amplifier circuit with the constant current circuit and then varying the current of the constant current circuit with the gain control signal.
CONSTITUTION: The points of difference are as follws. Constant current circuit 14 comprising transistor Tr15 and bias resistance R16 is provided, along with R17 and 18 (the other side of R17 earthed directly) to give a constant bias. Gain control input terminal 11 is connected to the base of Tr15 in circuit 14 to control the constant current level of circuit 14 with the gain control signal. Accordingly, capacitor 19 is charged with the current which flows forward through the base-emitter junction of Tr1 at the positive peak level of the signal of input 4 even in case the input signal of input terminal 4 increases in the strong electric field, and thus kept at the positive peak level of the signal of input 4. Thus, Tr1 always holds the breaking state to the input signal of over a certain level, causing no fluctuation of the modulation degree nor the distortion.
COPYRIGHT: (C)1979,JPO&Japio
JP274178A 1978-01-17 1978-01-17 Variable gain amplifier Pending JPS5496345A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP274178A JPS5496345A (en) 1978-01-17 1978-01-17 Variable gain amplifier

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP274178A JPS5496345A (en) 1978-01-17 1978-01-17 Variable gain amplifier

Publications (1)

Publication Number Publication Date
JPS5496345A true JPS5496345A (en) 1979-07-30

Family

ID=11537763

Family Applications (1)

Application Number Title Priority Date Filing Date
JP274178A Pending JPS5496345A (en) 1978-01-17 1978-01-17 Variable gain amplifier

Country Status (1)

Country Link
JP (1) JPS5496345A (en)

Similar Documents

Publication Publication Date Title
JPS57111116A (en) Comparator having hysteresis
JPS57173220A (en) Comparator circuit
JPS5515512A (en) Constant voltage output circuit
JPS52112261A (en) Power amplifier circuit
JPS5644209A (en) Signal converting circuit
JPS5516564A (en) Transistor amplifier circuit
JPS5496345A (en) Variable gain amplifier
JPS5592006A (en) Amplifier
JPS5597619A (en) Reference signal generating circuit
JPS555552A (en) Dc reproducing circuit
JPS55117971A (en) Level indication circuit
JPS5544266A (en) Rectifying circuit
JPS5731213A (en) Electric power amplifier
JPS5543643A (en) Constant voltage circuit
JPS5485634A (en) Dark current clipping circuit for television camera
JPS5516563A (en) Stabilizer circuit for video output voltage
JPS5494228A (en) Cut off adjustimg circuit for color receiving tube
JPS5481023A (en) High voltage generation circuit
JPS5534771A (en) Constant voltage circuit
JPS56168243A (en) Constant-voltage circuit
JPS55121734A (en) Variable impedance circuit
JPS5619121A (en) Constant electric current circuit
JPS567118A (en) Stabilizing electric power circuit
JPS57103414A (en) Current source circuit
JPS5571057A (en) Current limiting circuit