WO2003005565A1 - Electronic amplifier circuit - Google Patents
Electronic amplifier circuit Download PDFInfo
- Publication number
- WO2003005565A1 WO2003005565A1 PCT/GB2002/002993 GB0202993W WO03005565A1 WO 2003005565 A1 WO2003005565 A1 WO 2003005565A1 GB 0202993 W GB0202993 W GB 0202993W WO 03005565 A1 WO03005565 A1 WO 03005565A1
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- WIPO (PCT)
- Prior art keywords
- input terminal
- circuit
- amplifier unit
- output terminal
- high gain
- Prior art date
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Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/34—Negative-feedback-circuit arrangements with or without positive feedback
Definitions
- This invention relates to electronic amplifier circuits. It has application in electronic amplifier circuits which utilise high gain amplifier units such as operational amplifiers.
- operational amplifiers In general operational amplifiers have two input terminals, namely an inverting input terminal and a non-inverting input terminal, and an output terminal. If an input signal is applied to the inverting terminal and the non-inverting input terminal is connected to ground then a highly amplified version of the input signal appears at the output terminal.
- Negative feedback increases the frequency range over which the gain is constant, albeit with a reduction of the gain compared with its open loop value.
- harmonic distortion arises due to internal imperfections in the components and is still present even when negative feedback is provided and in fact increases with signal frequency.
- Typical values for harmonic distortion are 0.001% at 1kHz, 0.01% at 10kHz and 0.1% at 100kHz. The distortion increases by around 20dB per decade as the frequency increases.
- an electronic amplifier circuit comprises: an input terminal and an output terminal, a first high gain amplifier unit having two types of input terminal , namely an inverting input terminal and a non-inverting input terminal, and an output terminal, which output terminal is connected to the output terminal of the circuit, a connection including series resistance from the input terminal of the circuit to the inverting input terminal of the first amplifier unit, a negative feedback resistive path from the output terminal of the first amplifier unit to its inverting input terminal, a resistive path provided between the circuit output terminal and the circuit input terminal, which resistive path has an intermediate connection point, and an auxiliary high gain amplifier unit having two types of input terminal, namely an inverting input terminal and a non-inverting input terminal, and an output terminal, said intermediate connection point being connected to an input terminal of the auxiliary high gain amplifier unit of one type and the output terminal of the auxiliary high gain amplifier unit being connected to the input terminal of the other type of the first high gain amplifier unit.
- the gain of the auxiliary high gain amplifier is at least 100.
- said intermediate connection point may be connected to the non-inverting input terminal of the auxiliary high gain amplifier and the output terminal of the auxiliary amplifier is then connected to the inverting terminal of the main amplifier.
- said intermediate connection point may connected to the inverting input terminal of the auxiliary high gain amplifier and the output terminal of the auxiliary amplifier is then connected to the non-inverting terminal of the main amplifier, in which case resistance and capacitance in series can be connected between the non-inverting input terminal of the first amplifier unit and ground.
- Series resistance may be included between the output terminal of the auxiliary amplifier and the said input terminal of the first amplifier unit. Resistance and capacitance in series may be connected between an intermediate point in said series resistance and ground. Alternatively resistance and capacitance in series may be connected between the said input terminal and ground.
- one or more additional auxiliary amplifier units are provided, a separate resistive path associated with each additional auxiliary amplifier unit is provided between the circuit output terminal and the circuit input terminal, which resistive paths each have intermediate connection points, each of said intermediate connection points being connected to an input terminal of one type of its associated auxiliary high gain amplifier unit and the output terminal of the said associated auxiliary high gain amplifier unit being connected to the input terminal of the same type of the next auxiliary high gain amplifier (or, in the case of the last auxiliary amplifier unit, to the input terminal of the other type of the first high gain amplifier unit).
- Fig. 1 is a circuit diagram of an electronic amplifier circuit known from the prior art
- Fig. 2 is a circuit diagram of an electronic amplifier circuit known from the Pichal patent specification
- Fig. 3 is a circuit diagram of an electronic amplifier circuit embodying the invention
- Fig. 4 and Fig. 5 are circuit diagrams of further embodiments of the invention, and Fig. 6 is a circuit diagram yet another embodiment of the invention.
- Fig.1 there is shown therein a circuit diagram of a known electronic amplifier circuit having an input terminal Tl and an output terminal T2.
- Amplification is provided by a high gain amplifier unit Al.
- Unit Al comprises an operational amplifier having two types of input terminal, namely an inverting input terminal 10 and a non-inverting input terminal 1 1, and an output terminal 12.
- a series resistor Rl is connected between circuit input terminal Tl and inverting input terminal 10 of amplifier unit Al.
- Output terminal 12 of unit Al is connected to the output terminal T2 of the circuit.
- a negative feedback resistor R2 is connected between output terminal 12 and inverting input terminal 10 of amplifier unit Al.
- Non-inverting input terminal 11 of amplifier unit Al is connected to ground.
- the value of the open loop gain A is frequency dependant but the effect of the negative feedback is to maintain A n constant over a wide range of frequencies, albeit at the cost of reduction of some of the gain below its open loop level A.
- frequency dependant distortion is introduced in practical operational amplifier units and is present in sufficient magnitude to be a problem even with the inclusion of negative feedback.
- FIG. 2 In an endeavour to mitigate the effects of distortion the circuit of Fig. 2 has been proposed in US Patent No. 3,825,854 to Pichal.
- FIG.2 like parts have like reference numerals to Fig. 1.
- Additional components in the circuit of Fig. 2 comprise a pair of resistors R3 and R4 connected in series between input terminal Tl and output terminal T2.
- a second amplifier unit A2 is provided having an inverting input terminal 20 and an output terminal 22.
- a connection is taken from junction 23 between resistors R3 and R4 to inverting terminal 20 of amplifier A2 and the output terminal 22 of unit A2 is connected to the non-inverting terminal 11 of amplifier unit Al .
- Unit A2 provides inversion only and no amplification. Its gain is therefore -1 (or in one embodiment -2). It can be shown that the harmonic distortion F 2 for the Fig. 2 circuit with an open loop gain A for amplifier unit Al is given by
- FIG. 3 A circuit which embodies the inventive concept described herein and which results in a dramatic reduction of distortion is shown in Fig. 3 .
- like components have like reference numerals to Fig. 1 and Fig. 2.
- Amplifier unit A3 has an inverting input terminal 30, a non- inverting input terminal 31 and an output terminal 32.
- a connection is made from junction 23 between resistors R3 and R4 to non-inverting input terminal 31.
- Inverting terminal 30 is grounded and the output terminal is connected through an optional series resistor R5 to inverting input terminal 10 of amplifier unit Al.
- Amplifier unit A3 provides auxiliary feedback to the input of main amplifier unit Al .
- This auxiliary feedback represents a highly amplified version of a proportion of the difference between the input signal at Tl and the distorted output signal at T2.
- This amplified signal acts to significantly reduce the distortion.
- the value of open loop gain B is very much greater than the ratio R2/R1.
- R2/R1 10 and B > 100.
- Fig. 4 shows a circuit which is similar to the circuit of Fig. 3 and like parts have like references.
- output resistor R5 of auxiliary amplifier unit A3 which is shown in Fig. 3 is replaced by two resistors R6 and R7 in series and at the junction 40 between resistors R6 and R7 a path to ground is taken through a resistor R8 and a capacitor Cl in series.
- Resistor R8 and capacitor Cl act to provide frequency compensation.
- Fig. 5 shows another circuit which is similar to the circuit shown in Fig.3.
- a connection is taken from junction 23 between resistors R3 and R4 to the inverting input terminal 30 of auxiliary amplifier umt A3 and the non-inverting terminal 31 of unit A3 is grounded.
- the auxiliary feedback signal from the output resistor R5 of umt A3 is applied in the correct phase it is fed to non-inverting terminal 11 of the main amplifier unit Al .
- the circuit of Fig. 5 operates in like manner to the circuit of Fig. 3.
- a frequency compensation arrangement which has a similar function to the frequency compensation components shown in Fig. 4.
- This arrangement comprises a resistor R9 and a capacitor C2 connected in series between non-inverting input terminal 11 of amplifier unit Al and ground.
- the circuit of Fig. 6 may be used.
- like components have like references to Fig. 3 and those components operate in the same manner as described in Fig.3. That is to say, a main amplifier unit Al is provided with negative feedback through resistor R2 and to reduce distortion an auxiliary feedback high gain amplifier unit A3 is provided.
- the input to unit A3 is taken from junction 23 between two resistors R3 and R4 connected between input terminal Tl and output terminal T2 of the circuit. This input is a measure of the distortion introduced in unit Al.
- the output of unit A3 is applied through resistor R5 to an input terminal of unit Al in a manner to reduce the distortion.
- a further auxiliary high gain amplifier unit A4 is provided.
- Amplifier unit A4 is connected to still further reduce distortion. Its input is taken from the junction 63 between two resistors R63 and R64 connected between input terminal Tl and output terminal T2. Resistors R63 and R64 are in parallel with resistors R3 and R4.
- the output of auxiliary amplifier unit A4 is taken through a series output resistor R65 to junction 23. The effect of the additional auxiliary amplifier unit A4 is to reduce the distortion present at junction 23 to considerably below the level that it would be without the presence of amplifier unit A4 and thus to still further reduce the distortion introduced in main amplifier unit Al.
- resistor Rl and likewise resistors R3 and R63 is Ik ⁇ and for resistors R2, R4 and R64 is lOk ⁇ .
- Resistors R5 and R65 can have a value of 20k ⁇ . If desired more auxiliary amplifier units can be added to the circuit of Fig. 6 in a similar configuration to amplifier unit A4. The input to each additional amplifier unit is taken from the junction between an additional pair of resistors in series connected between the circuit input terminal Tl and the circuit output terminal T2. The output of each additional amplifier unit is taken to the junction between the previous pair of series resistors.
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Amplifiers (AREA)
Abstract
An electronic amplifier circuit comprises a first high gain amplifier unit (A1) having an inverting input terminal (10), a non-inverting input terminal (11) and an output terminal (12). An input signal is supplied from a circuit input terminal (T1) through a series input resistor (R1) to the inverting input terminal (10) of the first high gain amplifier unit (Al). A negative feedback resistor (R2) is connected between the output terminal (12) and the inverting input terminal (10) of the first high gain amplifier unit (A1). A pair of resistors (R3 and R4) are connected in series between the circuit input terminal (T1) and the circuit output terminal (T2). An auxiliary high gain amplifier unit (A3), preferably having a gain of at least 100, has its non-inverting input terminal (31) connected to the 'unction (23) between the pair of resistors (R3 and R4) and its output terminal (32) connected to the inverting input terminal (10) the first high gain amplifier unit (Al).
Description
ELECTRONIC AMPLIFIER CIRCUIT
Technical Field
This invention relates to electronic amplifier circuits. It has application in electronic amplifier circuits which utilise high gain amplifier units such as operational amplifiers. In general operational amplifiers have two input terminals, namely an inverting input terminal and a non-inverting input terminal, and an output terminal. If an input signal is applied to the inverting terminal and the non-inverting input terminal is connected to ground then a highly amplified version of the input signal appears at the output terminal. Background Art
In practical operational amplifiers, although the gain is very high it is frequency sensitive and above a certain frequency (typically a few Hertz) reduces at around 20dB per decade. To improve the constancy of the gain of an operational amplifier it is known to provide negative feedback. Such negative feedback is provided by a resistive path from the output terminal of the operational amplifier to its inverting input terminal.
Negative feedback increases the frequency range over which the gain is constant, albeit with a reduction of the gain compared with its open loop value.
However a further problem with practical operational amplifiers is the generation of harmonic distortion within the amplifier itself. This distortion arises due to internal imperfections in the components and is still present even when negative feedback is provided and in fact increases with signal frequency. Typical values for harmonic distortion are 0.001% at 1kHz, 0.01% at 10kHz and 0.1% at 100kHz. The distortion increases by around 20dB per decade as the frequency increases.
Where an operational amplifier is being used as an audio signal amplifier a figure of even 0.01% distortion at 10kHz can give rise to audible intermodulation distortion signals when multiple audio input signals of different but similar frequencies are applied to such an amplifier. In certain radio frequency applications such as transmitter circuits for cellular telephones such distortion can make an operational amplifier unacceptable as an amplifier circuit. Additionally certain electronic components such as active filters and oscillators require low levels of harmonic distortion to operate effectively.
One suggested solution to the problem of distortion is described in US Patent No. 3,825,854 to Pichal. In the circuits described in that patent specification a proportion of the difference between the input and output signals obtained from the junction between two resistors connected in series between the input and output terminals is fed back to the non-inverting input of the operational amplifier through a phase inverter having a gain of -1 or, in one embodiment -2. Practical embodiments of the circuits described in Pichal have been shown to be unsatisfactory in reducing distortion.
It is an object of the invention to provide a circuit in which distortion introduced from within the circuit is substantially reduced. Disclosure of the Invention
According to the invention an electronic amplifier circuit comprises: an input terminal and an output terminal, a first high gain amplifier unit having two types of input terminal , namely an inverting input terminal and a non-inverting input terminal, and an output terminal, which output terminal is connected to the output terminal of the circuit, a connection including series resistance from the input terminal of the circuit to the inverting input terminal of the first amplifier unit, a negative feedback resistive path from the output terminal of the first amplifier unit to its inverting input terminal, a resistive path provided between the circuit output terminal and the circuit input terminal, which resistive path has an intermediate connection point, and an auxiliary high gain amplifier unit having two types of input terminal, namely an inverting input terminal and a non-inverting input terminal, and an output terminal, said intermediate connection point being connected to an input terminal of the auxiliary high gain amplifier unit of one type and the output terminal of the auxiliary high gain amplifier unit being connected to the input terminal of the other type of the first high gain amplifier unit.
Preferably the gain of the auxiliary high gain amplifier is at least 100. In carrying out the invention said intermediate connection point may be connected to the non-inverting input terminal of the auxiliary high gain amplifier and the output terminal of the auxiliary amplifier is then connected to the inverting terminal of the main amplifier. Alternatively said intermediate connection point may connected to the inverting input terminal of the auxiliary high gain amplifier and the output terminal
of the auxiliary amplifier is then connected to the non-inverting terminal of the main amplifier, in which case resistance and capacitance in series can be connected between the non-inverting input terminal of the first amplifier unit and ground.
Series resistance may be included between the output terminal of the auxiliary amplifier and the said input terminal of the first amplifier unit. Resistance and capacitance in series may be connected between an intermediate point in said series resistance and ground. Alternatively resistance and capacitance in series may be connected between the said input terminal and ground.
In embodiments of the invention one or more additional auxiliary amplifier units are provided, a separate resistive path associated with each additional auxiliary amplifier unit is provided between the circuit output terminal and the circuit input terminal, which resistive paths each have intermediate connection points, each of said intermediate connection points being connected to an input terminal of one type of its associated auxiliary high gain amplifier unit and the output terminal of the said associated auxiliary high gain amplifier unit being connected to the input terminal of the same type of the next auxiliary high gain amplifier (or, in the case of the last auxiliary amplifier unit, to the input terminal of the other type of the first high gain amplifier unit).
In order that the invention may be more fully understood reference will now be made to the accompanying drawings in which: Fig. 1 is a circuit diagram of an electronic amplifier circuit known from the prior art,
Fig. 2 is a circuit diagram of an electronic amplifier circuit known from the Pichal patent specification,
Fig. 3 is a circuit diagram of an electronic amplifier circuit embodying the invention,
Fig. 4 and Fig. 5 are circuit diagrams of further embodiments of the invention, and Fig. 6 is a circuit diagram yet another embodiment of the invention.
Referring now to Fig.1 there is shown therein a circuit diagram of a known electronic amplifier circuit having an input terminal Tl and an output terminal T2. Amplification is provided by a high gain amplifier unit Al. Unit Al comprises an operational amplifier having two types of input terminal, namely an inverting input terminal 10 and a non-inverting input terminal 1 1, and an output terminal 12. A series resistor Rl is connected between circuit input terminal Tl and inverting input terminal
10 of amplifier unit Al. Output terminal 12 of unit Al is connected to the output terminal T2 of the circuit. A negative feedback resistor R2 is connected between output terminal 12 and inverting input terminal 10 of amplifier unit Al. Non-inverting input terminal 11 of amplifier unit Al is connected to ground. For the above circuit the overall amplification An of the circuit for an open loop gain A of amplifier unit Al, where A has a high value (i.e. A » 1), is given approximately by An = A/(l + αx A) where αt is a feedback factor defined as α]=Rl/(Rl + R2). The value of the open loop gain A is frequency dependant but the effect of the negative feedback is to maintain An constant over a wide range of frequencies, albeit at the cost of reduction of some of the gain below its open loop level A. However frequency dependant distortion is introduced in practical operational amplifier units and is present in sufficient magnitude to be a problem even with the inclusion of negative feedback.
It can be shown that the reduction factor Fj for harmonic distortion for the Fig. 1 circuit having an amplifier unit Al with a high value open loop gain A (i.e. A » 1) and provided with negative feedback is given by
where IAI is the magnitude of the open loop gain A of amplifier unit Al While such a circuit does give some improvement in distortion in comparison with an open loop operational amplifier unit that is not provided with negative feedback the improvement is not very significant and the problem of distortion still persists.
In an endeavour to mitigate the effects of distortion the circuit of Fig. 2 has been proposed in US Patent No. 3,825,854 to Pichal. In Fig.2 like parts have like reference numerals to Fig. 1. Additional components in the circuit of Fig. 2 comprise a pair of resistors R3 and R4 connected in series between input terminal Tl and output terminal T2. A second amplifier unit A2 is provided having an inverting input terminal 20 and an output terminal 22. A connection is taken from junction 23 between resistors R3 and R4 to inverting terminal 20 of amplifier A2 and the output terminal 22 of unit A2 is connected to the non-inverting terminal 11 of amplifier unit Al . Unit A2 provides inversion only and no amplification. Its gain is therefore -1 (or in one embodiment -2). It can be shown that the harmonic distortion F2 for the Fig. 2 circuit with an open
loop gain A for amplifier unit Al is given by
F2 = l/(1 + α, lAi + α2 lAl ) (2) where a2 = R3/(R3 + R4)
Such a circuit give some further improvement in distortion in comparison with the negative feedback circuit of Fig. 1 the improvement is still not very significant.
A circuit which embodies the inventive concept described herein and which results in a dramatic reduction of distortion is shown in Fig. 3 . In fig. 3 like components have like reference numerals to Fig. 1 and Fig. 2. However in Fig.3 a high gain open loop amplifier unit A3 is provided instead of the unity gain inverting amplifier unit A2 that is shown in Fig. 2. Amplifier unit A3 has an inverting input terminal 30, a non- inverting input terminal 31 and an output terminal 32. A connection is made from junction 23 between resistors R3 and R4 to non-inverting input terminal 31. Inverting terminal 30 is grounded and the output terminal is connected through an optional series resistor R5 to inverting input terminal 10 of amplifier unit Al. Amplifier unit A3 provides auxiliary feedback to the input of main amplifier unit Al . This auxiliary feedback represents a highly amplified version of a proportion of the difference between the input signal at Tl and the distorted output signal at T2. This amplified signal acts to significantly reduce the distortion. It can be shown that the reduction factor F3 for the circuit of Fig. 3 is given by F3 - 1/(1 + α3 IAI + α3 α2 IAI IBI ) (3) where a3 = 1/(1 + R2/R1 + R2/R4) and IBI is the magnitude of the open loop gain B of amplifier unit A3. Preferably the value of open loop gain B is very much greater than the ratio R2/R1. Typically R2/R1 = 10 and B > 100.
The substantial further reduction in harmonic distortion over that obtained both with conventional negative feedback as shown in equation (1) and over the Fig. 2 circuit as shown in equation (2) is therefore shown by equation (3) to be the result of the open loop gain B of the auxiliary amplifier unit A3. This gain should therefore be as large as possible consistent with maintaining stable operation.
Fig. 4 shows a circuit which is similar to the circuit of Fig. 3 and like parts have like references. In Fig. 4 however output resistor R5 of auxiliary amplifier unit A3 which is shown in Fig. 3 is replaced by two resistors R6 and R7 in series and at the junction 40
between resistors R6 and R7 a path to ground is taken through a resistor R8 and a capacitor Cl in series. Resistor R8 and capacitor Cl act to provide frequency compensation.
Likewise Fig. 5 shows another circuit which is similar to the circuit shown in Fig.3. However in Fig. 5 by way of variation a connection is taken from junction 23 between resistors R3 and R4 to the inverting input terminal 30 of auxiliary amplifier umt A3 and the non-inverting terminal 31 of unit A3 is grounded. To ensure that the auxiliary feedback signal from the output resistor R5 of umt A3 is applied in the correct phase it is fed to non-inverting terminal 11 of the main amplifier unit Al . Thus far the circuit of Fig. 5 operates in like manner to the circuit of Fig. 3.
Additionally, in the Fig. 5 circuit a frequency compensation arrangement is provided which has a similar function to the frequency compensation components shown in Fig. 4. This arrangement comprises a resistor R9 and a capacitor C2 connected in series between non-inverting input terminal 11 of amplifier unit Al and ground. To yet further improve the reduction in distortion brought about by exercising the invention the circuit of Fig. 6 may be used. In the circuit of Fig. 6 like components have like references to Fig. 3 and those components operate in the same manner as described in Fig.3. That is to say, a main amplifier unit Al is provided with negative feedback through resistor R2 and to reduce distortion an auxiliary feedback high gain amplifier unit A3 is provided. The input to unit A3 is taken from junction 23 between two resistors R3 and R4 connected between input terminal Tl and output terminal T2 of the circuit. This input is a measure of the distortion introduced in unit Al. The output of unit A3 is applied through resistor R5 to an input terminal of unit Al in a manner to reduce the distortion. Additionally in the circuit of Fig. 6 a further auxiliary high gain amplifier unit A4 is provided. Amplifier unit A4 is connected to still further reduce distortion. Its input is taken from the junction 63 between two resistors R63 and R64 connected between input terminal Tl and output terminal T2. Resistors R63 and R64 are in parallel with resistors R3 and R4. The output of auxiliary amplifier unit A4 is taken through a series output resistor R65 to junction 23. The effect of the additional auxiliary amplifier unit A4 is to reduce the distortion present at junction 23 to considerably below the level that it would
be without the presence of amplifier unit A4 and thus to still further reduce the distortion introduced in main amplifier unit Al.
A typical value for resistor Rl and likewise resistors R3 and R63 is Ik Ω and for resistors R2, R4 and R64 is lOkΩ. Resistors R5 and R65 can have a value of 20kΩ. If desired more auxiliary amplifier units can be added to the circuit of Fig. 6 in a similar configuration to amplifier unit A4. The input to each additional amplifier unit is taken from the junction between an additional pair of resistors in series connected between the circuit input terminal Tl and the circuit output terminal T2. The output of each additional amplifier unit is taken to the junction between the previous pair of series resistors.
Claims
CLAIMS 1. An electronic amplifier circuit comprising: an input terminal and an output terminal, a first high gain amplifier unit having two types of input terminal , namely an inverting input terminal and a non-inverting input terminal, and an output terminal, which output terminal is connected to the output terminal of the circuit, a connection including series resistance from the input terminal of the circuit to the inverting input terminal of the first amplifier unit, a negative feedback resistive path from the output terminal of the first amplifier unit to its inverting input terminal, a resistive path provided between the circuit output terminal and the circuit input terminal, which resistive path has an intermediate connection point, a auxiliary high gain amplifier unit having two types of input terminal , namely an inverting input terminal and a non-inverting input terminal, and an output terminal, said intermediate connection point being connected to an input terminal of the auxiliary high gain amplifier unit of one type and the output terminal of the auxiliary high gain amplifier unit being connected to the input terminal of the other type of the first high gain amplifier unit.
2. The circuit as claimed in claim 1 in which the gain of the auxiliary high gain amplifier is at least 100.
3. The circuit as claimed in either one of the preceding claims in which said intermediate connection point is connected to the non-inverting input terminal of the auxiliary high gain amplifier and the output terminal of the auxiliary amplifier is connected to the inverting terminal of the main amplifier.
4. The circuit as claimed in claim 1 or claim 2 in which said intermediate connection point is connected to the inverting input terminal of the auxiliary high gain amplifier and the output terminal of the auxiliary amplifier is connected to the non- inverting terminal of the main amplifier.
5. The circuit as claimed in any one of the preceding claims in which series resistance is included between the output terminal of the auxiliary amplifier and the said input terminal of the first amplifier unit.
6. The circuit as claimed in claim 5 in which resistance and capacitance in series is connected between an intermediate point in said series resistance and ground.
7. The circuit as claimed in any one of claims 1 to 5 in which resistance and capacitance in series is connected between the non-inverting input terminal of the first amplifier unit and ground.
8. The circuit as claimed in any one of the preceding claims in which one or more additional auxiliary amplifier units are provided, a separate resistive path associated with each additional auxiliary amplifier unit is provided between the circuit output terminal and the circuit input terminal, which resistive paths each have intermediate connection points, each of said intermediate connection points being connected to an input terminal of one type of its associated auxiliary high gain amplifier unit and the output terminal of the said associated auxiliary high gain amplifier unit being connected to the input terminal of the same type of the next auxiliary high gain amplifier (or, in the case of the last auxiliary amplifier unit, to the input terminal of the other type of the first high gain amplifier unit).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0116458A GB0116458D0 (en) | 2001-07-05 | 2001-07-05 | Amplifier |
| GB0116458.1 | 2001-07-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2003005565A1 true WO2003005565A1 (en) | 2003-01-16 |
Family
ID=9917984
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/GB2002/002993 WO2003005565A1 (en) | 2001-07-05 | 2002-06-28 | Electronic amplifier circuit |
Country Status (2)
| Country | Link |
|---|---|
| GB (1) | GB0116458D0 (en) |
| WO (1) | WO2003005565A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2390946A (en) * | 2002-07-10 | 2004-01-21 | Aubrey Max Sandman | Improved secondary feedback |
| GB2400995A (en) * | 2003-03-28 | 2004-10-27 | Gary Miller | Linear amplifiers with distortion correction by current comparison |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3603891A (en) * | 1968-05-28 | 1971-09-07 | Const Radioelec Electron | Amplifying device with wide transmission band and slight drift enabling a continuous component to be transmitted |
| US4222012A (en) * | 1977-06-29 | 1980-09-09 | Nippon Gakki Seizo Kabushiki Kaisha | Amplifier device |
-
2001
- 2001-07-05 GB GB0116458A patent/GB0116458D0/en not_active Ceased
-
2002
- 2002-06-28 WO PCT/GB2002/002993 patent/WO2003005565A1/en not_active Application Discontinuation
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3603891A (en) * | 1968-05-28 | 1971-09-07 | Const Radioelec Electron | Amplifying device with wide transmission band and slight drift enabling a continuous component to be transmitted |
| US4222012A (en) * | 1977-06-29 | 1980-09-09 | Nippon Gakki Seizo Kabushiki Kaisha | Amplifier device |
Non-Patent Citations (1)
| Title |
|---|
| KLAASSEN ET AL: "COMPARISON OF QUASIFEEDFORWARD- AND FEEDBACK-CONTROLLED AMPLIFIER", ELECTRONICS LETTERS., vol. 12, no. 13, 24 June 1976 (1976-06-24), IEE STEVENAGE., GB, pages 318 - 319, XP002217254, ISSN: 0013-5194 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2390946A (en) * | 2002-07-10 | 2004-01-21 | Aubrey Max Sandman | Improved secondary feedback |
| GB2390946B (en) * | 2002-07-10 | 2006-07-12 | Aubrey Max Sandman | Electronic amplifier circuit |
| GB2400995A (en) * | 2003-03-28 | 2004-10-27 | Gary Miller | Linear amplifiers with distortion correction by current comparison |
| GB2400995B (en) * | 2003-03-28 | 2006-03-15 | Gary Miller | Linear amplifiers |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0116458D0 (en) | 2001-08-29 |
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