Distortion differential pair amplifier

An idealized mixer is a multiplier circuit that takes two signals and literally multiplies the values of each signal to provide an output. In one sense, this concept is easier to understand with multiplication of numbers. For example, there are two analog signals, each connected to an analog-to-digital converter ADC. The digital outputs from the two ADCs then provide numbers from each signal, and these numbers are updated over time. If the outputs of the ADCs are fed to a digital multiplier, then the output of the digital multiplier will provide a stream of numbers that are the product of the two streams of numbers from the outputs of the ADCs.

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• Electrical – Distortion Elimination with Differential Transistor Pair
• Create new playlist
• Transimpedance amplifier circuit
• What is the common-mode input voltage of an op-amp?
• Amplifier Distortion, DC-Offset, and You!
• US5394113A - High impedance low-distortion linear amplifier - Google Patents
• On Distortion in Digital Microwave Power Amplifiers

WATCH RELATED VIDEO: Audio Amplifier Distortion Types

Electrical – Distortion Elimination with Differential Transistor Pair

Year of fee payment : 4. Effective date : Year of fee payment : 8. An amplifier and a method are provided for converting a single ended signal to an amplified differential signal. The amplifier comprises an input configured to receive a single ended signal, a differential amplifier that outputs an amplified differential signal based on the single ended signal, and a compensator coupled to the differential amplifier and configured to inject an adjusted distortion compensating signal based on the even order distortion signal to compensate for a distortion in the amplified differential signal.

The method comprises receiving a single ended signal, converting the single ended signal to an amplified differential signal, and generating a distortion compensating signal to substantially cancel an even order distortion signal injected to the differential signal by the converting. Provisional Patent Application No. This disclosure relates to a method, a circuit, and a system for mitigating distortion in single-ended input to differential output circuits.

In many applications, it is desirable to use differential signals instead of single-ended signals. Differential signals typically result in better control of receiver circuitry, faster circuits, and lower power consumption. However, signals are often generated and initially transmitted as unbalanced single ended signals. In integrated circuits, passive baluns, which may be configured as a wire wrapped around a core, may be costly, complex and unsuitable for wide bandwidth applications.

Conversely, conventional active baluns, which may be configured as an active conversion circuit, are non-linear, cause unfavorable power dissipation and introduce undesirable distortion in the differential signals. In one aspect of the invention, an amplifier is provided for converting a single ended signal to an amplified differential signal, the amplifier comprising: an input configured to receive a single ended signal; a converter that outputs an amplified differential signal based on the single ended signal; and a compensator coupled to the converter and configured to receive an even order distortion signal and feedback an adjusted distortion compensating signal to compensate for a distortion in the amplified differential signal.

The amplifier may further comprise a summer coupled between an output of the compensator and an input of the converter. The compensator comprises an extractor configured to receive the amplified differential signal and extract a compensating level signal. The compensator further may comprise an optional gain adjuster configured to generate the adjusted distortion compensating signal based on the compensating level signal.

The adjusted distortion compensating signal may comprise the compensating level signal. The compensator may be further configured to generate the adjusted distortion compensating signal by adding the amplified differential signal and multiplying a result of the summing by a predetermined gain. The predetermined gain may comprise a one-half gain. The gain adjuster may be further configured to: receive the compensating level signal from the extractor; and generate the adjusted distortion compensating signal based on the compensating level signal.

A component of the adjusted distortion compensating signal may be added to an output of the converter. Another component of the adjusted distortion compensating signal may be added to another output of the converter. The converter may comprise two inputs configured to receive a differential signal; and two outputs configured to output said amplified differential signal.

The adjusted distortion compensating signal may comprise a pair of adjusted distortion compensating signal components. The adjusted distortion compensating signal may be added to the single ended signal. A signal transfer function of the single ended signal may be unaffected by operation of the amplifier. The amplifier may further comprise a loop gain substantially equal to zero. The amplified differential signal may be substantially linear to the single ended signal.

The amplifier may further comprise: a first summer coupled between an output of the converter and the compensator; and a second summer coupled between another output of the converter and the compensator, wherein the compensator is further configured to output one of the pair of adjusted distortion compensating signal components to the first summer, and the other of the pair of adjusted distortion compensating signal components to the second summer.

According to another aspect of the disclosure, a method is provided for mitigating second order distortion when converting a single ended signal to a pair of differential signals. The method comprises: receiving a single ended signal; converting the single ended signal to an amplified differential signal; and generating an adjusted distortion compensating signal to substantially cancel an even order distortion signal injected to the differential signal by the converting.

The adding may comprise: adding a component of the adjusted distortion compensating signal to a component of the amplified differential signal; and adding a second component of the adjusted distortion compensating signal to a second component of the amplified differential signal. The predetermined gain value may comprise a one-half gain.

The adjusted distortion compensating signal may be generated based on the compensating level signal. A signal transfer function of the single ended signal may be unaffected by the converting. According to a yet further aspect of the disclosure, a method is provided for mitigating second order distortion when amplifying a pair of differential signals to a pair of amplified differential signals, the method comprising: receiving a pair of differential signal components; amplifying the pair of differential signal components to a pair of amplified differential signal components; and generating an adjusted distortion compensating signal to substantially cancel an even order distortion signal injected in at least one of the pair of amplified differential signal components by the amplifying.

According to a still yet further aspect of the disclosure, a communication device is provided that comprises the amplifier according to the disclosure. The communication device may comprise a high definition television. Additional features, advantages, and embodiments of the disclosure may be set forth or apparent from consideration of the following detailed description, drawings, and claims. Moreover, it is to be understood that both the foregoing summary of the disclosure and the following detailed description are examples and are intended to provide further explanation without limiting the scope of the disclosure as claimed.

The accompanying drawings, which are included to provide a further understanding of the disclosure, are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the detailed description serve to explain the principles of the disclosure. No attempt is made to show structural details of the disclosure in more detail than may be necessary for a fundamental understanding of the disclosure and the various ways in which it may be practiced.

In the drawings:. It should be noted that the features illustrated in the drawings are not necessarily drawn to scale, and features of one embodiment may be employed with other embodiments as the skilled artisan would recognize, even if not explicitly stated herein.

Descriptions of well-known components and processing techniques may be omitted so as to not unnecessarily obscure teaching principles of the disclosed embodiments. The examples used herein are intended merely to facilitate an understanding of ways in which the disclosure may be practiced and to further enable those of skill in the art to practice disclosed the embodiments.

Accordingly, the examples and embodiments herein should not be construed as limiting. Moreover, it is noted that like reference numerals represent similar parts throughout the several views of the drawings. In the circuits shown, the active conversion circuit is arranged so that a signal transfer function of a single ended analog input signal V in remains unaffected, such as, for example, the input to output signal transfer function.

The circuit may have a loop gain of approximately zero. Moreover, the circuit may provide linearity between the pair of differential signal components outputted on outputs V OUT1 , V OUT2 and the single ended input signal V in received by the circuit. As seen in FIG. An input of the summer may be connected to a voltage source such as, e.

The summer may include a second input that may be connected to an output of the compensator via a line An output of the summer may be connected to an input of the converter The summer may include, for example, but is not limited to, a summing junction or an integrated circuit IC capable of summing at least two signals, without departing from the scope or spirit of the disclosure. The converter may include one or more single-input to dual-output amplifiers, which receive a single-ended unbalanced analog signal and convert the signal to a pair of differential balanced output signals.

Additionally or alternatively , the converter may include at least one differential amplifier that receives multiple input signals and provides multiple output signals. For example, the converter may include a differential amplifier that includes a pair of inputs for receiving a pair of differential component signals and a pair of outputs for outputting a pair of amplified differential component signals as discussed below with reference to FIG.

Typically, the even order differential distortion signal DFA may be output on the output line The even order differential distortion signal DFA may comprise a pair of differential distortion component signals DF 1 , DF 2 , having substantially equal amplitudes and frequencies, but substantially opposite polarities.

The common mode signals CM 1 , CM 2 and the differential distortion signal DFA may be generated in the converter as a result of, for example, the operation of internal components, such as, e.

Referring to FIGS. The compensator includes an extractor and an optional gain adjuster The extractor may include, for example, a dual-input to single-output amplifier, integrated circuit, or the like, that receives the signals from lines , , and adds the signals to extract the differential distortion signal DFA.

The extractor may output an adjusted distortion compensating signal DC on a line , when the optional gain adjuster is not included in the compensator ; or, the extractor may output a compensating level signal not shown when the optional gain adjuster is included in the compensator In the latter instance, the compensating level signal may be applied to an input of the optional gain adjuster through a line , which then may variably adjust a magnitude of the compensating level signal to provide the adjusted distortion compensating signal DC.

The optional gain adjuster may include, for example, one or more regulating amplifiers or linearizing amplifiers, including a single-input to single-output integrated circuit amplifier.

The extractor may include a variable gain, such as, e. The optional gain adjustor may be configured to receive the compensating level signal from the extractor over the line and vary the magnitude of the compensating level signal to generate the adjusted distortion compensating signal DC, which substantially balances or cancels the even order differential distortion signal DFA introduced by, for example, the converter , which may appear at the output V OUT2. For example, where the gain of the optional gain adjustor is fixed, the gain of the extractor may be variable.

Where the gain of the optional gain adjustor is variable, the gain of the extractor may be fixed. Moreover, the gains of both the extractor and the optional gain adjustor may be variable. Moreover, the extractor and the optional gain adjustor are configured to provide linearity between the amplified differential signal and the input single-ended signal.

The compensator may provide the adjusted distortion compensating signal DC to an input of the summer via the line to be added to the input signal V in , the result of which may be applied to the input of the converter to substantially cancel the even order differential distortion signal DFA.

In this instance, the adjusted distortion compensating signal from the compensator may be added to only one of the input differential component signals V in1 , V in2 to substantially cancel the even order differential distortion signal DFA generated by the converter As shown in FIG.

In this instance, to the adjusted distortion compensating signal from the compensator may be provided as a pair of adjusted distortion compensating component signals on the lines , , and input to the summers , , respectively.

The pair of adjusted distortion compensating component signals may, thus, be added to the input differential component signals V in1 , V in2 to substantially cancel the even order differential distortion signal DFA generated by the converter The process may begin upon, for example, initialization of the active conversion circuit Referring to FIG.

A determination may be made whether the received signal V in is a single-ended sinusoidal analog signal Step If the signal V in is determined to be a single-ended or unbalanced analog signal YES at Step , then the signal V in is applied to an amplified differential signal generator circuit such as, e. The amplified differential signals may be added by an extractor such as, e. Based on the extracted differential distortion signal DFA, a compensating level signal may be generated based on a variable gain such as, e.

The compensating level signal may then be used to generate an adjusted distortion compensating signal DC to substantially balance or cancel the even order differential distortion signal DFA Step The generated distortion compensating signal DC may be injected into the amplified differential signal generator circuit to substantially balance or cancel the even order differential distortion signal DFA, passing the common mode signals CM 1 , CM 2 unaffected Step It is again noted that like reference numerals represent similar parts throughout the drawings.

In other words, the circuit may be arranged so as not to modify the signal transfer function of the analog input signal. During operation of the circuit , the common mode signals CM 1 , CM 2 and the differential distortion signal DFA having differential distortion component signals DF 1 , DF 2 may be generated in the converter as a result of, for example, the operation of internal components, such as, e.

Referring to the waveforms shown FIG. The summer may be configured to receive one of the differential pair of output signals, e. An output of the summer may be connected to the output V OUT1. The feedforward signal. FF may be similar to the adjusted distortion compensating signal DC discussed earlier, which has substantially the same frequency and amplitude as the differential distortion signal DFA introduced by the converter , thereby substantially balancing or canceling the differential distortion signal DFA.

The circuit includes a pair of summers , , the converter and the compensator The compensator may be configured to include two outputs and a single input, as seen in FIG. The circuit may be arranged so as not to affect the signal transfer function of the analog input signal.

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Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It only takes a minute to sign up. Connect and share knowledge within a single location that is structured and easy to search. I have been dealing with these differential amplifiers for weeks now and still don't understand the basic principles of its operation and how should it be used inside an audio amplifier. I understand everything to the point when input say AC signal is applied to circuit. I completely do not understand how should negative feedback from output of amplifier back to non-inverting input do anything at all. All that distortion canceling within diff-amplifier pair negative feedback is totally unclear to me in practical way mostly.

Transimpedance amplifier circuit

The present application claims priority to U. Provisional Patent Application No. These voltage-to-current converters are configured to receive an input voltage and generate an output current. In order to achieve low total harmonic distortion i. The problems noted above are solved in large part by systems and methods of reducing total harmonic distortion of an amplifier. In some embodiments, a voltage-to-current converter includes a first differential pair of transistors, a second differential pair of transistors, and a first resistor. The first differential pair of transistors includes a first transistor and a second transistor. An emitter of the first transistor is directly connected to an emitter of the second transistor. The second differential pair of transistors includes a third transistor and a fourth transistor.

What is the common-mode input voltage of an op-amp?

A differential amplifier, which has good linearity and noise performance, includes a first side that includes first, second, third, and fourth transistors and an inductor. The first and second transistors are coupled as a first cascode pair, and the third and fourth transistors are coupled as a second cascode pair. The third transistor has its gate coupled to the source of the second transistor, and the fourth transistor has its drain coupled to the drain of the second transistor. The first transistor provides signal amplification. The second transistor

Amplifier Distortion, DC-Offset, and You!

The differential amplifier is probably the most widely used circuit building block in analog integrated circuits, principally op amps. We had a brief glimpse at one back in Chapter 3 section 3. It may have either one output or a pair of outputs where the signal of interest is the voltage difference between the two outputs. This is referred to as the common mode signal. It is often easiest to start again with the very basic single transistor and build a workable differential amplifier as a logical progression from there.

US5394113A - High impedance low-distortion linear amplifier - Google Patents

A differential input low distortion pre-amplifer concept. Hi all: I am trying to design a low distortion valve pre-amplifier for my audio system. The goal is : 1. Differential input 2. Flat frequence response. As low distortion as posible. So I begin to design the circuit. Firstly I shall use multisim.

On Distortion in Digital Microwave Power Amplifiers

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A method for improving or eliminating second harmonic and higher even order distortion terms and balance of fundamental signals in push-pull amplifiers and other differential circuits is disclosed. A common-mode CM signal is generated as a sum of two complementary out of phase signals in a summation network. The CM signal contains even order distortion terms only, while the fundamental signal and odd order distortion terms are canceled, thus providing a correction signal that can be used to reduce even order distortion terms, by injecting the correct The CM signal contains even order distortion terms only, while the fundamental signal and odd order distortion terms are canceled, thus providing a correction signal that can be used to reduce even order distortion terms, by injecting the correction signal, with proper phase and amplitude, into suitable circuit nodes. For feedback, the correction signal is injected at the input of the amplifiers, for feed-forward, it's injected at the output. The correction signal can be amplified to higher levels and injected into the circuit, without affecting gain of fundamental signals; and can result in significant even order distortion improvements, and improved balance of complementary fundamental signals.

Digital-to-analog converters are widely used in many different applications and an amplifier often accompanies them to signal-condition the output. The amplifier functions to increase output current drive, to convert differential to single ended output, to isolate the downstream signal path, or to provide a complementary bipolar output voltage. Figure 1 shows a typical section of a single supply signal chain, consisting of a voltage reference, a digital-to-analog converter, and a buffer. To maintain a high dynamic output range and high signal-to-noise ratio, digital-to-analog converters DACs are often designed to operate full swing, where the reference voltage VREF is set equal to the supply voltage VDD. This allows maximum usage of the digital codes. With a single supply, the DAC and the output buffer power supply are often connected to the same supply line.

Most of you know that incorporation of negative feedback within amplifier is one of major considerations when designing a hi-fi amplifier. Till now, I have only dealt with differential transistor pair as input stage of amplifier and "eliminator" of distortions fed back from output of an amplifier. Although, I'm not quite sure if all kinds of distortions get eliminated by it when compared to the original signal brought to the input of amplifier. This circuit proposed and made by user G36 has distorted signal, which is being delivered to voltage-amplification stage and after that it gets corrected to original sine wave signal being brought to the input of amplifier.