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Topic: Bias voltage

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	Articles by Randall Smith - Bias Adjustment
		It's a static voltage and regardless of what tube is in the socket -- or even if the tubes aren't plugged in at all, it doesn't change the bias voltage a bit.
		Voltage is the degree of electric charge -- like the "pressure" to use the old water analogy.
		Be that as it may, when the original bias voltage is altered far enough, it will compensate for the tube's abnormal performance and the correct amount of idle current flow may then be restored.
	www.mesaboogie.com /US/Smith/biasadjust.html (1878 words)

	Integrated CMOS circuit comprising a substrate bias voltage generator - Patent 4820936
		In an integrated circuit, an externally-clocked substrate bias voltage pump and a stand-by bias voltage generator are provided, the latter not being switched on until the substrate bias voltage becomes less negative than, for example, -2V.
		The invention relates to an integrated CMOS circuit comprising a substrate bias voltage generator, which is driven by a clock generator, which also controls further circuits in the integrated circuit.
		The voltage between the gate electrode and the main electrode at the junction point 14 between the NMOS transistor 12 and the PMOS transistor 20 is then no longer higher than the threshold voltage of the NMOS transistor N12.
	www.freepatentsonline.com /4820936.html (1656 words)

	Protection of analog reference and bias voltage inputs - Patent 5218506
		An analog reference or bias voltage power supply can be located as part of (on chip) or separate from (off chip) a CMOS circuit chip but must be filtered off chip since a capacitor needed for the power supply filter is typically too large to be placed on chip.
		The polarity of the voltage supply terminal is positive in the event the field effect transistor is of n-channel type and negative in the event the field effect transistor is of p-channel type.
		The gate of the n-channel transistor is connected to a positive voltage supply and the gate of the p-channel transistor is connected to a negative voltage supply.
	www.freepatentsonline.com /5218506.html (2557 words)

	Biasing techniques : BIPOLAR JUNCTION TRANSISTORS (Site not responding. Last check: )
		The greater the instantaneous voltage of the input signal, the greater the duty cycle of the output squarewave pulse.
		Bias voltage in a transistor circuit forces the transistor to operate at a different level of collector current with zero input signal voltage than it would without that bias voltage.
		DC bias voltage on the input signal, necessary for certain classes of operation (especially class A and class C), may be obtained through the use of a voltage divider and coupling capacitor rather than a battery connected in series with the AC signal source.
	www.allaboutcircuits.com /vol_3/chpt_4/8.html (3096 words)

	Bias Cells
		Unless large by-pass condensers are used with a filter network, cathode bias, or bias derived from the voltage drop in the negative lead of the power supply system, has many disadvantages.
		The bias voltage variation is responsible for many undesirable effects, such as instability, loss of bass note amplification, and distortion.
		Bias cells should not be used to bias oscillators, power output tubes, or amplifier tubes in which grid current may exist.
	www.philcorepairbench.com /biascell.htm (1828 words)

	[No title] (Site not responding. Last check: )
		The negative voltage then leaves the middle wiper of the bias pot and goes to a junction where two 220K 1/2 watt resistors are soldered together at one end.
		If you want to be able to bias each power tube at 35ma of current, adjust the bias range resistor until you can get more than 35ma when the bias pot is turned all the way one way and less than 35ma when the bias pot is turned all the way the other way.
		This AC voltage is much higher than what a dedicated bias tap puts out so it must be brought down quite a bit to use for the bias voltage.
	www.hoffmanamps.com /charts/Biascircuits.htm (2045 words)

	Semiconductor memory device having a back-bias voltage generator (USRE34797)
		In typical MOS integrated circuit devices, the level of the back-bias voltage which is generated by a built-in back-bias generation circuit and is supplied to a semiconductor substrate is changed by an undesirable leakage current flowing through the semiconductor substrate.
		To reduce the change of the back-bias voltage resulting from the change of the leakage current, a back-bias voltage generation circuit is provided which has output capacity of a plurality of levels.
		The level change of the back-bias voltage generation circuit can further be reduced by providing a level detection circuit for detecting the level change and a feedback circuit for controlling the back-bias voltage generation circuit in accordance with the output of the level detection circuit.
	www.delphion.com /details?pn10=USRE034797 (476 words)

	NOS Valves - Tube Amplifier Repair - Scott 296 Rebuild
		What I did was tap into the bias voltage supply for the balance controls and install a 25k potentiometer to feed each balance control.
		You feed on leg the voltage and hook the center wiper to the center wiper of the balance pot.
		The other leg of the bias voltage control is run to ground through the resistor this resistor value is how you adjust the range of voltage you will be able to apply to the grids of the output tubes.
	www.nosvalves.com /rebuild.htm (1130 words)

	Shure - Products
		Bias supplies power to a Junction Field Effect Transistor (JFET) connected to the output of an electret condenser mic element.
		In some condenser microphones, the bias voltage must be supplied on the same conductor as the audio.
		A dynamic microphone should not be connected to an input that supplies bias voltage (such as a wireless transmitter) because the audio and the bias voltage will travel down the same conductor.
	www.shure.com /ProAudio/Products/us_pro_ea_phantom (568 words)

	Detector diodes with bias control loop invention
		For example, the correct bias voltage is a strong function of the temperature of the avalanche photodiode chip.
		The method generally includes using a feedback loop that senses the current output from a sense diode to maintain a bias voltage at the sense diode that is sufficient to bring the sense diode close to or into its breakdown state.
		A feedback loop that is connected to the current sensor is used to maintain a bias voltage at the detector diode that is sufficient to bring the detector diode close to or into its breakdown state regardless of the optical power being received by the detector diode.
	www.freshpatents.com /Detector-diodes-with-bias-control-loop-dt20061005ptan20060219872.php (1805 words)

	VHF/UHF Long Yagi Workshop
		It is very important that the bias supply maintains a fairly constant output voltage, even at maximum current demand; if it fails to do that, the RF drive will bias the transistor back towards Class C, causing heavy splatter on speech peaks.
		The voltage drop across the forward-biased diode D1 is approximately the same as the voltage drop across the transistor's base-emitter junction, and by adjusting RV1 to send the correct current through D1, the collector current in TR1 can be set to the desired value.
		Bias regulation totally fails when peaks of RF drive create a heavy demand for base current, so this circuit is a real splatter-generator.
	www.ifwtech.co.uk /g3sek/tr-bias/tr-bias1.htm (2156 words)

	[muRata]Rotary Sensor Information (Site not responding. Last check: )
		Bias voltage is an output obtained by bringing the magnetic balance into uniformity in the potential divider circuit.
		The bias voltage at reverse rotation differs by a maximum of 10 mV from that at normal rotation when the applied voltage is 5 V. The magnetic field generated by the permanent magnet incorporated in the sensor changes with the rotation of the pulser (gear).
		Due to the gap difference, the difference between bias voltage at normal rotation and that at reverse rotation is greater when the gap is 0.2 mm than when it is 0.6 mm.
	www.murata.com /rotary/appli8.html (287 words)

	Bias Voltage Circuit for Kyocera STN LCDs
		A subpixel is controlled by applying or not applying a voltage between the column electrode and the row electrode.
		The certain way to determine if the customer must provide the bias circuit is to look at the interface signal table in section 8 of the full specification.
		The amount of bias voltage must be the same.
	americas.kyocera.com /kicc/lcd/notes/biascircuit.html (277 words)

	BJT Bias Design
		Hence, it is a good idea to set the bias for a single stage amplifier to half the supply voltage, as this allows maximum output voltage swing in both directions of an output waveform.
		This is similar to the self bias circuit with one difference: the base resistor Rb is returned to the transistor collector instead of the supply voltage.
		A bias circuit is required to bias a transistor to half the supply voltage.
	www.zen22142.zen.co.uk /Design/bjtbias.htm (1875 words)

	What Is Biasing?
		Fixed biasing means the tube is biased by means of a DC voltage, which is usually a negative voltage applied to the grid of the tube with respect to the cathode.
		As the bias voltage is adjusted less negative, towards zero volts DC, the bias current becomes larger, and the tube is biased "hotter".
		This is the same as keeping the cathode at ground and applying a negative DC voltage to the grid, because it is the grid voltage with respect to the cathode that determines the amount of bias current in the tube.
	www.aikenamps.com /WhatIsBiasing.htm (995 words)

	Amplifier auto bias circuits: Class-A, Class-AB!
		The bias voltage that works so handsomely when the output tubes were new may not work as well a few months later or when one output tube is replaced.
		The zener’s break voltage is purposely set higher than the bias voltage, so that when the amplifier leaves class-A, the zener limits the maximum voltage the capacitor can charge up to, which prevents under biasing the amplifier after a large current swing.
		Given a long enough period of excessive current swinging, the bias voltage will be thrown far too negative and the once class-A amplifier might end up operating in class-C, as the output devices might be completely biased off (of course, some tubes are so sloppy at their cutoff region that they never cut off).
	www.tubecad.com /2005/April/blog0043.htm (1713 words)

	BT-250 Bias Tee
		The BT-250 is a low noise bias insertion tee with a DC blocking capacitor that was designed specifically for use with the SXUV/UVG series photodiodes.
		The BT-250 is rated for up to 250V applied bias and an optional BT-500 is available with voltage rating up to 500 V. The BT-250 has 3 ports that should be connected with BNC cables to an oscilloscope, DC power supply and photodiode.
		It is estimated that the measured output of the BT-250 is approximately 5% less than the actual output of the diode due to the loss in the bias tee.
	www.ird-inc.com /biastee.html (212 words)

	Reverse bias breakdown
		The resulting breakdown voltage is inversely proportional to the doping density if one ignores the weak doping dependence of the electric field at breakdown.
		The resulting breakdown voltages and depletion layer widths are plotted below as a function of the doping density of an abrupt one-sided junction.
		Breakdown voltage and depletion layer width at breakdown versus doping density of an abrupt one-sided p-n diode.
	ece-www.colorado.edu /~bart/book/book/chapter4/ch4_5.htm (699 words)

	Wilcoxon: Knowledge desk FAQs
		The bias voltage, sometimes referred to as the rest voltage, is required to measure AC signals using two wire single ended amplifiers.
		When using sensors with 12 volt bias, it is generally recommended that the supply voltage exceed 24 volts to increase the amplitude range performance of the sensor.
		Transient voltage suppressors should be built into the amplifier to prevent permanent damage to semiconductors in the electronics.
	www.wilcoxon.com /knowdesk_faqs.cfm (4618 words)

	IR3084UMTRPBF Datasheet IR3084UMTRPBF PDF IC-ON-LINE.CN-Free DataSheet Search and Download Site
		Adaptive Voltage Positioning (AVP) Adaptive Voltage Positioning (AVP) is needed to reduce the total output voltage deviations during load transients and to reduce the power dissipation of the load when it is drawing high current.
		The voltage at the VDRP pin is a buffered version of the current share bus (Iin) and represents the sum of the VDAC voltage and the average inductor current of all the phases.
		Figure 9 - Temperature compensation of inductor DCR Remote Voltage Sensing To compensate for impedance in the ground plane, the VOSNS- pin is used for remote ground sensing and connects directly to the load.
	kr.ic-on-line.cn /IOL_ir3084umtrpbf/PdfView/800019.htm (10531 words)

	LT3437EFE Datasheet LT3437EFE PDF IC-ON-LINE.CN-Free DataSheet Search and Download Site
		BIAS (Pin 6/Pin 10): The BIAS pin is used to improve efficiency when operating at higher input voltages and light load current.
		FB (Pin 8/Pin 12): The feedback pin is used to determine the output voltage using an external voltage divider from the output that generates 1.25V at the FB pin.
		The bias regulator normally draws power from the VIN pin, but if the BIAS pin is connected to an external voltage higher than 3V, bias power will be drawn from the external source (typically the regulated output voltage).
	kr.ic-on-line.cn /IOL_lt3437efe/PdfView/779986.htm (8644 words)

	Bias FAQ
		(In other words, rotate the bias trimmer until you obtain the highest negative voltage that the bias supply is capable of delivering.) Note that on some really old amps, the bias supply may be controlled by the standby switch; if you see no negative voltage on pin FIVE, you may have one of these amps.
		Note that the incoming line voltage directly affects all of the voltages in the amp; you may want to read the line voltage occasionally to see if this is happening.
		Some amps have a "balance" type bias adjustment, which allows you to vary the negative grid voltage between the two halves of the output stage; this makes a "matched" set of tubes less crucial to good performance, although it can't compensate for tubes that are wildly different.
	www.duncanamps.com /technical/lvbias.html (4234 words)

	EOT - Electro-Optics Technology, Inc.
		If it is less than the specified bias voltage, it may be necessary to replace the batteries.
		As a general rule of thumb, the saturation of the photodetectors occurs at output voltages that are about 1/3 that of the bias voltage.
		The photodiode is probably shorted, allowing all of some of the bias voltage to appear at the output of the photodetector.
	www.eotech.com /techsupport/photodetectors/faqs.php (740 words)

	Firmware-Adjustable LCD Bias Generator Swings Outside The Rails
		However, LCD bias voltage is relatively insensitive to ripple, and rapid changes aren’t needed, making this application ideal for PWM techniques.
		The function that describes the behavior of the output voltage with PWM duty cycle is a quadratic, with the minimum at 50% duty cycle.
		The actual attainable output voltage falls in the range of +1 to −3 V. This is ideal for the application, because the typical LCD bias voltage is required to be about +0.5 V at high temperatures, falling to around −2 V at extremely cold temperatures.
	www.elecdesign.com /Articles/ArticleID/6221/6221.html (1077 words)

	BJT Bias Design
		Hence, it is a good idea to set the bias for a single stage amplifier to half the supply voltage, as this allows maximum output voltage swing in both directions of an output waveform.
		This is similar to the self bias circuit with one difference: the base resistor Rb is returned to the transistor collector instead of the supply voltage.
		A bias circuit is required to bias a transistor to half the supply voltage.
	www.mitedu.freeserve.co.uk /Design/bjtbias.htm (1875 words)

	Base bias tuned VFO (Site not responding. Last check: )
		In general, an increase in bias voltage causes the oscillator to increase in frequency and visa versa.
		You also need to choose bias resistor values to prevent Q1 from going into saturation as the tuning potentiometer is turned to the right and the bias voltage is increased.
		In the case of this oscillator, changing the bias voltage alters the intrinsic capacitance of the CE junction of Q1 but unfortunately, also changes the operating point and oscillation amplitude.
	www.qrp.pops.net /base_bias_vfo.htm (2395 words)

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