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Tube cascode differential amplifiers

Warning: this build requires measurement and adjustment of high voltage circuits. This requires excellent safety habits as well as testing equipment like a variac. Some portions of the circuit are best built on PCBs. There is no shortage of worthwhile projects to choose from: variations on Williamson , Mullard , or Dynaco push-pull topologies are easy to find discussed in forums and tweaked to compensate for modern parts. You can even find kits for something like the Dynaco ST When the double-digit power bug bit me I could not bring myself to abandon my usual no-feedback, triode output, class A comfort zone.

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Tube cascode differential amplifiers

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Cascode Amplifier Working and Its Applications


OF DE. Effective date : Year of fee payment : 4. OF MN. Year of fee payment : 8. Year of fee payment : A bipolar integrated circuit amplifier with a cascode stage has an emitter follower biasing circuit which provides a bias voltage to the cascode stage. The cascode amplifier stage is stabilized by providing a stabilization capacitance across the base-collector junction of the emitter follower in the biasing circuit. Field of the Invention. The present invention relates to a bipolar integrated circuit amplifier.

In particular, the present invention is an improved amplifier circuit having a cascode amplifier stage. The use of a cascode stage to broad band an amplifier stage is commonly used and practiced in integrated circuit design.

This configuration, however, is prone to instability and becomes more susceptable to oscillation with increased current levels which are desirable in low noise applications. One typical amplifier having a cascode amplifier stage is a differential amplifier having a pair of transistors with their emitters connected together and their bases connected to receive the two input signals.

The collector of the two differential amplifier transistors are connected to the emitters of the cascode stage transistors. The bases of the cascode stage transistors are connected to a bias voltage. The collectors of the cascode stage transistors are connected through resistors to a supply line. In the prior art, attempts have been made to stabilize the cascode amplifier stage of the differential amplifier circuit by including resistors in the emitters of the cascode transistors or by using compensation capacitors between the supply line and the collectors of the cascode transistors.

Both of these prior art methods decrease the frequency response of the amplifier circuit. In addition, emitter resistors increase the differential input capacitance of the differential amplifier transistors. The present invention is based upon the discovery that stabilization of an amplifier having a cascode stage can be achieved by providing additional base-collector capacitance to the transistor of the emitter follower biasing circuit used to provide the bias voltage for biasing the cascode stage.

This stabilization capacitance across the base-collector junction has been found to stabilize a cascode type amplifier without band limiting the amplifier's frequency response. Stabilization is also achieved without sacrificing low input capacitance. Cascode differential amplifier 10 includes a differential amplifier having a pair of input terminals 12 and 14 and a pair of output terminals 16 and Power is supplied to amplifier 10 at a pair of supply terminals 18 and NPN transistors Q1 and Q2 have their bases connected to input terminals 12 and 14, respectively.

The emitters of Q1 and Q2 are connected together to current source I1. NPN transistors Q3 and Q4 form a cascode stage. The emitter of Q3 is connected to the collector of Q1, and the emitter of Q4 is connected to the collector of Q2.

The collector of Q3 is connected through resistor R1 to supply terminal 18, and the collector of Q4 is connected through resistor R2 to supply terminal Resistors R3 and R4 and diodes D1-D7 are connected in series between terminals 18 and 20 to orm a voltage divider which applies a base voltage to transistor Q5.

Q5 is an NPN transistor having its collector connected to supply terminal 18 and its emitter connected through resistor R5 to supply terminal The bias voltage REF 1 is derived from the emitter of Q5. We have discovered that by including capacitor C1 across the base collector junction of transistor Q5, the favorable stable operation of the cascode differential amplifier is achieved without band limiting the frequency response and without sacrificing low input capacitance.

Normally, the base-collector capacitance of Q5 is on the order of about 0. Capacitance C1 is on the order of about 1 to about pf, and preferably about 4 pf. In a preferred embodiment of the present invention, capacitor C1 is a junction capacitor formed in parallel with the base collector junction of transistor Q5. Alternatively, capacitor C1 and the base-collector junction of Q5 can be combined simply by making the base-collector junction larger while retaining the same size emitter as when the two capacitances were separate.

Capacitance C1, however, can be any type of capacitor, not necessarily a junction capacitor. Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.

For example, although the preferred embodiment shown in the Figure is a differential amplifier having a cascode stage, the present invention is also applicable to single-ended amplifiers having a cascode stage which receives a bias potential from an emitter follower bias generator.

In addition, R5 can be replaced by a current source, and R3, R4 and D1-D7 can be replaced by other circuits which generate a bias voltage at the base of Q5.

What is claimed is: 1. A bipolar integrated circuit amplifier having a cascode stage which receives a bias voltage from an emitter-follower bias circuit which includes a transistor having a base, an emitter and a collector, means for providing a base voltage to the base of the transistor, means for deriving the bias voltage from the emitter of the transistor, and stabilization capacitance means between the base and collector of the transistor for stabilizing the cascode stage of the bipolar integrated circuit amplifier.

The invention of claim 1 wherein the stabilization capacitance means has a capacitance of between about 1 pf and about pf. The invention of claim 1 wherein the stabilzation capacitance means has a capacitance of about 4 pf. The invention of claim 1 wherein the means for providing a base voltage includes a voltage divider connected between first and second supply terminals.

The invention of claim 4 wherein the transistor has its collector connected to the first supply terminal and its emitter connected through a load to the second supply terminal.

The invention of claim 1 wherein the amplifier has a differential amplifier stage connected to the cascode stage. The invention of claim 6 wherein the differential amplifier stage includes first and second differential stage transistors having bases connected to first and second input terminals, respectively; having emitters connected together to a current source; and having collectors connected to the cascode stage. The invention of claim 7 wherein the cascode stage includes first and second cascode stage transistors having bases connected to the bias circuit to receive the bias voltage and having emitters connected to the collectors of the first and second differential stage transistors, respectively.

The invention of claim 8 wherein the first and second cascode stage transistors have collectors connected through first and second resistance means to a first supply terminal. The invention of claim 9 wherein the first and second differential stage transistors are NPN transistors and the first and second cascode stage transistors are NPN transistors.

The invention of claim 10 wherein the transistor of the bias is an NPN transistor. The invention of claim 1 wherein the stabilzation capacitance means is a junction capacitor. USA en.

Level converter circuit converting input level into ECL-level against variation in power supply voltage. MR head preamplifier with output signal amplitude which is independent of head resistance. USB1 en. USB2 en. Differential amplifier circuit providing high gain output at low power supply voltage.

JPB2 en. EPB1 en. KRB1 en.


Cmos differential amplifier pdf

A differential amplifier is an amplifier that amplifies the difference between two voltages and rejects the average or common mode value of the two voltages. What causes the common mode gain in mos differential amplifier. Then from superposition theorem, the output voltage v out is equal to v out. Shashidhar et al: design and implementation of cmos telescopic op-amp for bio-medical. This paper presents a new cmos fully differential current feedback operational amplifier fdcfoa. In analog circuits, we are often focused on amplifiers in which the small signal behavior is of high importance-large signal calculations lead to the operating point information of the circuit which is used to determine the small signal model of the device example amplifier circuit: r s r g r d v in v out v bias i d 1 solve for bias current i d. The ratios between differential gain and power supply gains furnish the two psrrs.

7). If the control. Fig., 7. Use of a pentode B2 for producing a high differential resistancein the common cathode lead of the tubes Bi and Bi'.

AES E-Library


Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. DOI: Paulik and Raymond P. Paulik , R. Mayer Published Computer Science, Engineering IEEE Transactions on Education A differential amplifier composed of an emitter-coupled pair is useful as an example in lecture presentations and laboratory experiments in electronic circuit analysis courses. View on IEEE. Save to Library Save. Create Alert Alert.

Fully-differential amplifiers

tube cascode differential amplifiers

ReturnTo Theme-Group-Choice. Distributed constant amplifiers e. Double-ended push-pull DEPP or balanced push-pull amplifiers. Impedance conversion amplifiers e.

Cascode — The cascode is a two stage amplifier composed of a transconductance amplifier followed by a current buffer.

cascode amplifier


Because we build OTL amplifiers, people often think that we are making a conventional Futterman design. This is untrue. Our products are designed around a central concept: that symmetrical designs are inherently low distortion, with excellent stability. We build output transformerless circuits that embrace this idea. This paper is designed to shed some light on the technology involved.

~ Triode Cascode Amplifier Calculator ~

A power efficient high output swing operational "HOOP" amplifier for integrated circuit analog signal processing is described. The operational amplifier includes a differential input stage and an output stage. The differential input stage is powered by a regular power supply while the output stage is powered by a voltage multiplier which results in a high voltage output swing without sinking significant power from the voltage multiplier. The high output voltage e. An output isolation technique is An output isolation technique is utilized to prevent possible latchup and contention. The operational amplifier also features a bias boot scheme to achieve a faster settling time from power up.

The cascode is a two-stage amplifier that consists of a common-emitter stage feeding into a common-base stage. Compared to a single amplifier stage.

As good as the Dynaco transformers are easily equaling the performance of the most prestigious tube amplifiers available , we knew that they were not perfect. Driven by this constant need to improve, we began a quest to identify a completely transparent transformer. Unfortunately, after an exhaustive audible evaluation of all currently available transformers, we were forced to conclude that in one way or another, a critical flaw would surface to disqualify each contender. We then asked Mike LaFever of Magnequest, to work with us to co-develop a transformer to our specifications.

The cascode amplifier is used to enhance the performance of an analog circuit. The utilization of cascode is a common method which can be used in the applications of transistors as well as vacuum tubes. The tern cascode was used in an article which can be written by Roger Wayne Hickman and Frederick Vinton Hunt in the year The discussion is on the voltage stabilizers applications.

Cascode is a technique implied to improve the performance of the analog circuits.

User Name Stay logged in? What Tube for a Differential Amplifier? Hi there, I am looking for some help to define the most appropriate tube to use at the input stage of an hybrid amplifier. Let me give you the topic : I want to make an amplifier whose input stage is a differential stage using two triodes, ouput stage will be all bipolar. I want to have a 40Vpeak on one of the triode plate for a single input of 1V peak. So I need at least 40 for amplification.

Provisions that are valid at a general level e. The structural association with elements coupled with amplifiers can be classified either in H03F or in the subclass covering the element or in both the subclasses , depending on which aspect is more relevant. In particular H03F units represented as "black boxes" in a specific application e. Amplifiers capable only of dealing with pulses, electronic switches, comparators, logic circuits, PWM signals.




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