A multiple transconductance amplifier

Abstract

The present application relates to a kind of multiple transconductance amplifier, characterized in that, including operational transconductance amplifier, first threshold control device, second threshold control device, threshold control device includes current source, for output threshold current;Input end, for obtaining the first current of operational transconductance amplifier output;Current processing device, for comparing the numerical value of threshold current and first current, when first current is greater than threshold current, after the operation of threshold current and first current, output adjustment current;Total output end, first current and adjustment current, after the operation of output total current.The present application provides a kind of multiple transconductance implementation, can be according to the change of output voltage, judge whether the output current exceeds the set threshold, if exceeding threshold, then automatically adjust output current, so that the transconductance value of the overall circuit changes.

Description

Technical Field

[0001] This invention relates to the field of electronic circuits, and more specifically to a multi-transconductance amplifier. Background Technology

[0002] In power factor correction (PFC) technology, the design of the error amplifier is often the primary factor determining loop stability. Due to the characteristics of the input waveform, the bandwidth of the control loop must typically be designed to be quite low to maintain loop stability. However, a low bandwidth design can lead to a slower loop response, potentially causing overshoot or undershoot of the output voltage.

[0003] Against this backdrop, the technique of multi-gm transconductance has been used to address this problem. By using different transconductance values ​​(gm) based on the output voltage information, the error amplifier can provide different loop bandwidths. There are many ways to implement multi-gm transconductance in an error amplifier, the simplest of which is to use multiple error amplifiers with different transconductances. For example... Figure 1 As shown, different error amplifiers can be selected based on different output voltage information to provide various transconductance values. However, this implementation requires the use of multiple error amplifiers, thus resulting in relatively high costs. Another existing method involves adding an additional current to the output of the error amplifier based on the output voltage information, but this method still requires additional circuitry to detect the output voltage and increase the current. This results in more components, higher costs, and a larger circuit area. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention discloses a multi-transconductance amplifier.

[0005] The technical solution adopted in this invention is as follows:

[0006] A multi-transconductance amplifier, characterized in that it includes:

[0007] An operational transconductance amplifier, including a first output terminal for outputting a first current;

[0008] The first threshold control device includes: a first current source for outputting a first threshold current; a first input terminal for acquiring the first current; and a first current processing device for comparing the value of the first threshold current and the first current, and when the first current is greater than the first threshold current, calculating the first threshold current and the first current and outputting a first adjustment current.

[0009] The second threshold control device includes: a second current source for outputting a second threshold current, wherein the value of the second threshold current is different from that of the first threshold current; a second input terminal for acquiring the first current; and a second current processing device for comparing the values ​​of the second threshold current and the first current, wherein when the first current is greater than the second threshold current, the second threshold current and the first current are processed and a second adjustment current is output.

[0010] At the total output terminal, the first current, the first adjustment current, and the second adjustment current are obtained, and the total current is output after calculation.

[0011] Its further technical solution is as follows:

[0012] The first current processing device is an upper current mirror, which includes: an upper input terminal for acquiring a first current; and an upper output terminal for outputting a first adjustment current.

[0013] The second current processing device is a lower current mirror, which includes: a lower input terminal for acquiring a first current; and a lower output terminal for outputting a second adjustment current.

[0014] The further technical solution is as follows: the operational transconductance amplifier further includes a second output terminal for outputting a second current; a third output terminal for outputting a third current; the second current and the third current are equal in value; the upper input terminal is coupled to the second output terminal; and the lower input terminal is coupled to the third output terminal.

[0015] A further technical solution is that the transmission ratios of the upper current mirror and the lower current mirror are different.

[0016] Its further technical solution is as follows:

[0017] The operational transconductance amplifier further includes: a first current mirror, including a first current branch and a second current branch; a second current mirror, including: a third current branch coupled to the first current branch; a fourth current branch; a third current mirror, including: a fifth current branch; a sixth current branch coupled to the second current branch; and a differential input stage, including: a first output branch coupled to the fourth current branch; and a second output branch coupled to the fifth current branch.

[0018] Wherein: the coupling terminal of the second current branch and the sixth current branch serves as the output terminal of the operational transconductance amplifier, used to output the first current.

[0019] The further technical solution is as follows: the first current mirror further includes: a seventh current branch; an eighth current branch;

[0020] The third current mirror further includes: a ninth current branch coupled to the seventh current branch; and a tenth current branch coupled to the eighth current branch.

[0021] In the first current mirror, the first current branch provides a reference current, and the seventh, eighth, and second current branches form multiple output branches of the multi-channel current mirror. In the third current mirror, the fifth current branch provides a reference current, and the ninth, tenth, and sixth current branches form multiple output branches of the multi-channel current mirror. The first input terminal acquires the electrical signal at the coupling terminal of the seventh and ninth current branches, and the second input terminal acquires the electrical signal at the coupling terminal of the eighth and tenth current branches.

[0022] The further technical solution is that the transmission ratio of the first current mirror, the second current mirror, and the third current mirror is 1.

[0023] The further technical solution is that the magnitudes of the first threshold current and the second threshold current are different and the directions are opposite.

[0024] The beneficial effects of this invention are as follows:

[0025] This invention provides a method for implementing multiple transconductance. It can determine whether the output current exceeds a set threshold based on the change in output voltage. If it exceeds the threshold, the output current is automatically adjusted so that the overall transconductance value of the circuit changes. This achieves the effect of multiple transconductance using only one error amplifier, and no other circuit structure is needed to detect the specific value of the current. Only a threshold current needs to be set and the current is compared with it.

[0026] Furthermore, the present invention proposes a specific implementation in which a multi-transconductance circuit structure can be achieved by adding only a few sets of current sources and current mirrors to the original circuit, making the circuit design simpler, the circuit area smaller, and the lowest cost achieved by minimizing the number of transistors. Attached Figure Description

[0027] Figure 1 This is one implementation of multiple transconductance in the prior art.

[0028] Figure 2 This is a circuit structure block diagram of an embodiment of the present invention. Detailed Implementation

[0029] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0030] Example 1.

[0031] The multi-transconductance amplifier in Embodiment 1 includes an operational transconductance amplifier, a first threshold control device, a second threshold control device, and a total output terminal.

[0032] The operational transconductance amplifier includes a first output terminal. The input signal to the operational transconductance amplifier is a differential voltage. The first output terminal outputs a first current I. o .

[0033] The first threshold control device includes a first current source, a first input terminal, and a first current processing device. The first current source is a constant current source, providing a first threshold current I. A The first input terminal is used to obtain the first current I. o The first current processing device compares the value of the first threshold current with that of the first current. When the first current is greater than the first threshold current, it sets the first threshold current I... A and the first current I o After the calculation, the first adjustment current I is output. GMA .

[0034] In this embodiment and other embodiments, the operations are defined as addition and subtraction of the current value based on the direction of the current. That is, when the current direction is the same, the current value is added, and when the current direction is opposite, the current value is subtracted.

[0035] The second threshold control device includes a second current source, a second input terminal, and a second current processing device. The second current source is a constant current source, providing the second threshold current I. B The second input terminal is used to obtain the first current I. o The second current processing device compares the values ​​of the second threshold current and the first current. When the first current is greater than the second threshold current, it sets the second threshold current I... B and the first current I o After the calculation, the second adjustment current I is output. GMB .

[0036] The total output terminal will have the first current I o First adjustment current I GMA Second adjustment current I GMB The total output current I after calculation o '.

[0037] In this embodiment, both the first threshold control device and the second threshold control device acquire the first current I output by the operational transconductance amplifier. o Then, using the current value of the constant current source as the comparison threshold, based on the first current I... oIf the threshold is exceeded, adjust the total current I output from the total output terminal. o '.

[0038] A low-bandwidth design tends to result in a slower loop response, potentially leading to overvoltage or undervoltage at the output. This is related to the output voltage V. O Change. Output voltage V O The change means the output current I O A change in current means the output current may exceed the threshold. This generates an adjustment current to control the magnitude of the total output current, thus changing the total transconductance. This allows the circuit to achieve multiple transconductance using only one error amplifier, without requiring other circuitry to detect the specific current value; only a threshold current needs to be set for comparison.

[0039] Example 2.

[0040] Based on Embodiment 1, in Embodiment 2, the first current processing device is specifically an upper current mirror. The second current processing device is specifically a lower current mirror. The upper current mirror includes an upper input terminal and an upper output terminal. The upper input terminal is used to acquire the first threshold current I. A and the first current I o The upper output terminal is used to output the first adjustment current I. GMA The lower current mirror includes a lower input terminal and a lower output terminal. The lower input terminal is used to obtain the second threshold current I. B and the first current I o The lower output terminal is used to output the second adjustment current I. GMB .

[0041] Preferably, the operational transconductance amplifier has three output terminals, including a second output terminal for outputting a second current; a third output terminal for outputting a third current; the second current and the third current have equal values; the upper input terminal is coupled to the second output terminal; and the lower input terminal is coupled to the third output terminal. In this way, the operational transconductance amplifier has three output terminals, and the output current values ​​are equal but independent of each other, so the threshold current does not affect the operational transconductance amplifier itself.

[0042] In Embodiment 1, the first current processing device can also be implemented using various other specific circuit structures, as long as it has the following function: it can process the first threshold current I. A and the first current I o The comparison and addition are performed, and the result is output to the total output terminal. The second current processing device works similarly. Example 2 uses a current mirror to achieve this function, employing fewer circuit components, further reducing the complexity of the circuit structure and the circuit area. Example 3

[0043] Based on Embodiment 1 or Embodiment 2, Embodiment 3 further specifies the structure of the operational transconductance amplifier.

[0044] The operational transconductance amplifier includes a first current mirror, a second current mirror, a third current mirror, and a differential input stage. The transfer ratios of the first, second, and third current mirrors are all 1.

[0045] The first current mirror includes a first current branch and a second current branch.

[0046] The second current mirror includes a third current branch and a fourth current branch. The third current branch is coupled to the first current branch.

[0047] The third current mirror includes a fifth current branch and a sixth current branch. The second current branch is coupled to the sixth current branch.

[0048] The differential input stage includes a first output branch, a second output branch, and two input branches. The two input branches are used to input the differential voltage V. INN and V INP The first output branch is coupled to the fourth current branch, and the second output branch is coupled to the fifth current branch.

[0049] The coupling terminal of the second current branch and the sixth current branch serves as the first output terminal, outputting the first current I. o .

[0050] In this embodiment and other embodiments of this application, coupling is defined as the state in which electrical signals can be transmitted between circuit lines, such as a direct connection of wires.

[0051] Furthermore, based on the circuit described above, the operational transconductance amplifier can be modified.

[0052] The first current mirror further includes a seventh current branch and an eighth current branch.

[0053] The third current mirror further includes a ninth current branch and a tenth current branch. The ninth current branch is coupled to the seventh current branch, and the tenth current branch is coupled to the eighth current branch.

[0054] In the first current mirror, the first current branch provides the reference current, and the seventh, eighth, and second current branches form multiple output branches of the multi-channel current mirror. In the third current mirror, the fifth current branch provides the reference current, and the ninth, tenth, and sixth current branches form multiple output branches of the multi-channel current mirror. The coupling terminals of the seventh and ninth current branches are the second output terminals, outputting a second current I. OA This is used to transmit an electrical signal to the first input terminal. The coupling terminal of the eighth current branch and the tenth current branch is the third output terminal, outputting the third current I.OB It is used to transmit electrical signals to the second input terminal.

[0055] In this implementation, the operational transconductance amplifier has three output terminals, which are used to output the first current I. O Second current I OA and the third current I OB This makes each circuit structure more independent, and the threshold current does not affect the operational transconductance amplifier itself.

[0056] The operating principle of this embodiment is explained below. The operating principles of Embodiments 1 and 2 can also be derived based on the specific circuit structure selected.

[0057] The first, second, and third output terminals are all output terminals of the operational transconductance amplifier, and the output current values ​​are equal, represented by the current I shown in the diagram. O If the direction is positive, then I have O =-I OA =I OB .

[0058] Hereafter, let I A If it is a negative value, I B It is a positive value. When I A If I is a positive value, B The principle remains the same when the value is negative.

[0059] For the operational transconductance amplifier itself, its transconductance values ​​are:

[0060] gm_base=I O / (V INP -V INN );

[0061] That is, I O =(V INP -V INN )*gm_base.

[0062] When the current I O When I is positive, meaning it's in the same direction as shown in the diagram, the upper current mirror does not generate current. For the lower current mirror, if I... O <I B That is, I OB <I B At this time, the current mirror does not generate current. If I O >I B , (V INP -V INN )*gm_base>I B That is, I OB >I B At this time, a current I2 is generated at the lower input terminal, and at terminal B:

[0063] I2+I B -I OB =0;

[0064] I2=-I B +I OB =-I B +I O ;

[0065] I GMB =N B *I2=N B *(-I B +I O ).

[0066] At this time, the current I output from the total output terminal O '=I O +I GMB =I O +N B *(-I B +I O );

[0067] The transconductance of the multi-transconductance amplifier is:

[0068] GmB = I O ' / (V INP -V INN ) = [I O +N B *(-I B +I O )] / (V INP -V INN ).

[0069] When the current I O When the value is negative, that is, in the opposite direction to that shown in the figure, the lower current mirror does not generate current. For the upper current mirror, if |I O |<I A I OA <I A The current mirror does not generate current. If |I O |>I A , (V INN -V INP )*gm_base>I A That is, I OA >I A The upper input terminal generates a current I1, which has the following at terminal A:

[0070] I1+I A -I OA =0;

[0071] I1=-IA +I OA =-I A -I O ;

[0072] I GMA =N A *I1=N A *(I A +I O ).

[0073] At this time, the current I output from the total output terminal O '=I O +I GMA =I O +N A *(I A +I O );

[0074] The transconductance of the multi-transconductance amplifier is:

[0075] GmA = I O ' / (V INP -V INN ) = [I O +N A *(I A +I O )] / (V INP -V INN )

[0076] It can be seen that when the output current I O The change causes the output current I to change. O If the current is too large or too small, exceeding the threshold current output by the first or second current source, an adjustment current will be generated to control the magnitude of the current at the total output terminal. This will change the total transconductance value, achieving a multi-transconductance effect using only a single error amplifier. Furthermore, no other circuit structure is needed to detect the specific current value; only a current mirror circuit structure is used to compare the operational transconductance amplifier with the threshold current and automatically feed back to the total output terminal, changing the total output current I. O The transconductance value of the multi-transconductance amplifier changes when the output voltage is adjusted. The error amplifier obtains multiple transconductances, and these multiple transconductances are automatically adjusted according to the output voltage information. This means that the error amplifier provides different loop bandwidths, resulting in better circuit characteristics.

[0077] In the various embodiments of the present invention, the specific structure and principle of the current mirror are basic electrical concepts in the art, well known to those skilled in the art, and are not improvements of this application, and are not specifically shown in this application document.

[0078] The above description is an explanation of the present invention and not a limitation thereof. The scope of the present invention is defined by the claims. The present invention can be modified in any form without departing from its basic structure.

Claims

1. A multiple transconductance amplifier characterized by, The operation trans-impedance amplifier comprises: a first output end for outputting a first current; a first threshold control device comprising: a first current source for outputting a first threshold current; a first input end for obtaining the first current; a first current processing device for comparing the first threshold current and the first current, and outputting a first adjustment current when the first current is greater than the first threshold current; a second threshold control device comprising: a second current source for outputting a second threshold current, the second threshold current being different from the first threshold current; a second input end for obtaining the first current; a second current processing device for comparing the second threshold current and the first current, and outputting a second adjustment current when the first current is greater than the second threshold current; a total output end for obtaining the first current, the first adjustment current and the second adjustment current, and outputting a total current after operation.

2. The multiple trans-impedance amplifier according to claim 1, wherein: the first current processing device is an upper current mirror, the upper current mirror comprising: an upper input end for obtaining the first current; an upper output end for outputting the first adjustment current; the second current processing device is a lower current mirror, the lower current mirror comprising: a lower input end for obtaining the first current; a lower output end for outputting the second adjustment current.

3. The multiple trans-impedance amplifier according to claim 2, wherein: the transmission ratios of the upper current mirror and the lower current mirror are different.

4. The multiple trans-impedance amplifier according to claim 2, wherein: the operation trans-impedance amplifier further comprises: a second output end for outputting a second current; a third output end for outputting a third current; the second current and the third current have equal values; the upper input end is coupled to the second output end; and the lower input end is coupled to the third output end.

5. The multiple trans-impedance amplifier according to claim 1, wherein: the operation trans-impedance amplifier further comprises: a first current mirror comprising a first current branch and a second current branch; a second current mirror comprising: a third current branch coupled to the first current branch; a fourth current branch; a third current mirror comprising: a fifth current branch; a sixth current branch coupled to the second current branch; a differential input stage comprising: a first output branch coupled to the fourth current branch; a second output branch coupled to the fifth current branch; wherein: the coupled ends of the second current branch and the sixth current branch serve as output ends of the operation trans-impedance amplifier for outputting a first current.

6. The multiple trans-impedance amplifier according to claim 5, wherein: the first current mirror further comprises: a seventh current branch; an eighth current branch; the third current mirror further comprises: a ninth current branch coupled to the seventh current branch; a tenth current branch coupled to the eighth current branch; In the first current mirror, the first current branch provides a reference current, and the seventh, eighth and second current branches form multiple output branches of a multi-path current mirror; in the third current mirror, the fifth current branch provides a reference current, and the ninth, tenth and sixth current branches form multiple output branches of a multi-path current mirror; the first input end acquires an electrical signal from the coupled ends of the seventh and ninth current branches; and the second input end acquires an electrical signal from the coupled ends of the eighth and tenth current branches.

7. The multiple trans-impedance amplifier of claim 5, wherein: The transmission ratios of the first, second and third current mirrors are all 1.

8. The multiple trans-impedance amplifier of claim 1, wherein: The first threshold current and the second threshold current have different current values and opposite directions.

Images