An automatic drawing method for on-chip transformers

Abstract

The present invention discloses a method for automatically drawing an on-chip transformer, which can be applied to a variety of structures, including interleaved interwinding transformers, symmetrical interwinding transformers, and symmetrical stacked transformers. The method for automatically drawing an on-chip transformer of the present invention can realize the drawing of transformers with arbitrary polygons, different structures, and multiple turn ratios, and can add tap structures at any position, which can cover common radio frequency circuit application scenarios. Compared with traditional manual drawing, the present invention only needs to provide the required structural parameters and structure types to quickly output the transformer layout, greatly improving the design efficiency of passive devices. At the same time, the present invention combines geometric prior knowledge to pre-screen the drawn structure, and the automatic modeling success rate can reach 100%. The method of the present invention promotes the automation and intelligence of radio frequency circuit design while ensuring the success rate.

Description

Technical Field

[0001] The present invention relates to an automatic drawing method for an on-chip transformer, which can quickly realize structural modeling compared with traditional manual layout drawing and belongs to the field of radio frequency passive devices. Background Art

[0002] On-chip transformers are critical components in RF integrated circuits (RFICs). Their shape significantly impacts circuit layout, and the lack of accurate and rapid performance evaluation techniques has become a bottleneck in RF and millimeter-wave circuit design. From a designer's perspective, the most pressing concerns are transformer performance, modeling, and the time required to achieve a suitable physical layout, as these significantly impact the design cycle and even tape-out success. Transformer models provided by foundries typically have a limited frequency range and limited accuracy. In some cases, the process design kit lacks a transformer model, or the existing model doesn't meet the requirements, making the design more difficult and requiring the designer to redesign the transformer.

[0003] Manual transformer drawing is feasible but time-consuming, especially when multiple turns are involved. Routing becomes more challenging, and constant full-wave electromagnetic simulation is required to iteratively modify parameters. The overall circuit layout and area must also be considered. Automatically drawing transformers on-chip allows designers to quickly design a large number of transformers for selection while also limiting structural parameters, significantly improving design efficiency. Summary of the Invention

[0004] Purpose of the invention: In response to the problems and shortcomings of the prior art, the present invention provides a method for automatically drawing an on-chip transformer. By providing only structural parameters such as the transformer's inner diameter, line width, line spacing, and number of turns, the transformer layout can be quickly generated. Compared with traditional manual structure drawing, this method greatly improves the work efficiency of RF circuit designers.

[0005] Technical solution: In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0006] A method for automatically drawing an on-chip transformer comprises the following steps:

[0007] Obtain on-chip transformer structural parameters, including inner ring polygon shape, inner diameter, line width, line spacing, and number of turns;

[0008] Determine the positions of the vertices of the inner circle, and the unit direction vector and unit normal vector of each side of the inner circle polygon according to the shape and inner diameter of the inner circle polygon;

[0009] The vertices of the primary and secondary coils are obtained by translating the unit direction vectors of each side along the unit normal vector and intersecting them. The translation distance is determined according to the line width and line spacing of the transformer.

[0010] Adjust the input and output port coordinates and arrange the wiring.

[0011] Furthermore, the position of each vertex of the inner circle is determined according to the number of edges and the inner diameter, including: using polar coordinates to determine the polar diameter of each vertex and angular coordinates Get the vertex polar coordinates (R,θ i ), and then converted to rectangular coordinates; where D in is the inner diameter, n is the number of sides of the regular polygon;

[0012] The rectangular coordinates are used to calculate the equations of the lines forming the edges between the adjacent vertices, thereby obtaining the unit direction vector and the unit normal vector of each edge.

[0013] Furthermore, the on-chip transformer is an interleaved interwinding transformer, in which the primary coil and the secondary coil are interleaved and wound on the same metal layer and are centrally symmetrically distributed; the input ports of the two-pole coils are connected to the outermost circle of metal, and the output ports are connected to the innermost circle of metal via through holes; the line width and line spacing of the primary coil and the secondary coil are the same.

[0014] Furthermore, the on-chip transformer is a symmetrical interwinding transformer, whose primary coil and secondary coil are wound in parallel on the same metal layer and are axially symmetrically distributed; the input and output ports of the primary coil are directly connected to the outermost circle of metal, and the input and output ports of the secondary coil are connected to the outermost circle of metal via through holes; the line width and line spacing of the primary coil and the secondary coil are the same.

[0015] Furthermore, the primary and secondary coils of the symmetrical interwinding transformer are drawn separately. After the transformer prototype is drawn according to the innermost polygon, the coil is divided into two symmetrical parts by the median line, and then the connection order of the metal segments is determined. Finally, the two symmetrical parts of metal are bridged in sequence to draw the cross-wiring part.

[0016] Furthermore, determining the connection order of the metal segments includes:

[0017] Divide the coil into two parts, left and right. Number each section of metal sequentially from the outside to the inside and distinguish the head and tail. Remember that the left coil has the head on top and the tail below, and the right coil has the head below and the tail on top. When drawing the crossover traces, always go from the head to the tail.

[0018] Set the routing flag flag. A flag of 1 indicates inward routing, and a flag of -1 indicates outward routing. The initial flag is 1. Starting from the metal segment labeled 1, discuss each case. If the current metal label is not equal to 2, continue to judge the flag. If the flag is 1 and the current metal segment is in the innermost circle, connect the head of the current metal segment to the tail of the other half of the circle, update the label, and update the flag flag to -1. If the flag is 1 and the current metal segment is not in the innermost circle, connect the head of the current metal segment to the tail of the other half of the inner circle and update the label. If the flag is -1, connect the head of the current metal segment to the tail of the other half of the outer circle and update the label.

[0019] Furthermore, the on-chip transformer is a symmetrical stacked transformer, whose primary coil and secondary coil are wound in parallel on multiple metal layers and are axially symmetrically distributed; the input and output ports of the primary coil are directly connected to the outermost circle of metal, and the input and output ports of the secondary coil are connected to the outermost circle of metal via through holes; the line width and line spacing of the primary coil and the secondary coil are the same.

[0020] Furthermore, the method also includes drawing the transformer tap, first determining the metal segment number of the tap, and then determining the metal relative position parameter; in an interleaved interwinding transformer, the tap can be assigned to the entire area, and in a symmetrical interwinding transformer and a symmetrical stacked transformer, the tap can be assigned to the area except the cross-wiring part.

[0021] Furthermore, the method combines geometric prior knowledge to pre-screen the drawn structure, and determines specific constraints based on the transformer structure and the number of turns of the primary and secondary coils to ensure correct modeling, including: after the center line is translated to the left and right sides to form a bridge, the inner side of the metal segment does not reach the inflection point; after the through hole is added, the outer side of the metal segment does not reach the inflection point; when the number of turns of the primary and secondary coils is different, it should be ensured that the bridge is formed and the inflection point is not reached after the lead-out port.

[0022] A computer program product includes a computer program / instruction, which implements the steps of the on-chip transformer automatic drawing method when executed by a processor.

[0023] Beneficial effects: Compared with the prior art, the on-chip transformer automatic drawing method provided by the present invention has the following advantages:

[0024] (1) The present invention only requires the structural parameters of the transformer to automatically draw the on-chip transformer and output the layout, greatly improving the work efficiency of RF circuit designers;

[0025] (2) The present invention supports transformer drawing with three structures, namely, arbitrary polygonal interleaved winding, symmetrical interwinding, and symmetrical stacking, and multiple turn ratios. It can add tap structures, has diverse functions, and can cover common RF application scenarios.

[0026] (3) The present invention can combine geometric prior knowledge to screen the drawn structure, so that the success rate of automatic drawing of on-chip transformers reaches 100%, promoting the automation and intelligent design of radio frequency circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the unit direction vectors of the sides and the normal unit direction vector of the inner quadrilateral;

[0028] Figure 2 Schematic diagram of the process of drawing metal based on coordinates for the interlaced quadrilateral transformer;

[0029] Figure 3 This is a comparison diagram of the port coordinates of the staggered quadrilateral transformer before and after adjustment;

[0030] Figure 4 Automatically draw a structural example diagram for an interleaved quadrilateral transformer;

[0031] Figure 5 The prototype of the symmetrical inter-wound quadrilateral transformer and the schematic diagram of the translation vector;

[0032] Figure 6 It is a schematic diagram of the translation of the two sides of the symmetrically wound quadrilateral transformer;

[0033] Figure 7 It is a schematic diagram of metal markings of a symmetrically wound quadrilateral transformer;

[0034] Figure 8 This is a schematic diagram of the cross wiring of a symmetrical interwinding quadrilateral transformer;

[0035] Figure 9 This is a schematic diagram of the midpoint translation bridge of the symmetrical inter-winding structure;

[0036] Figure 10 Automatically draw a structural example diagram for a symmetrical interwound quadrilateral transformer;

[0037] Figure 11 Automatically draw structural example diagrams for various on-chip transformers. DETAILED DESCRIPTION

[0038] To make the objectives, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0039] An embodiment of the present invention discloses an automatic drawing method for an on-chip transformer, the main steps of which include: first, obtaining the structural parameters of the on-chip transformer, including the inner circle polygon shape, inner diameter, line width, line spacing and number of turns; then, determining the positions of each vertex of the inner circle, as well as the unit direction vector and unit normal vector of each side of the inner circle polygon based on the inner circle polygon shape and inner diameter; then, obtaining each vertex of the primary and secondary coils by translating and intersecting the unit direction vectors of each side along the unit normal vector, wherein the translation distance is determined according to the transformer line width and line spacing; finally, adjusting the coordinates of the input and output ports and arranging the wiring.

[0040] The method of the embodiment of the present invention is applicable to a variety of on-chip transformer structures, including interleaved interwinding transformers, symmetrical interwinding transformers, and symmetrical stacked transformers. It can realize the drawing of transformers with arbitrary polygons and multiple turn ratios, and can add tap structures to cover common RF circuit application scenarios. The primary and secondary coils of the interleaved interwinding transformer are interleaved on the same metal layer and are distributed symmetrically around the center. The input ports of the two-stage coils are connected to the outermost metal ring, and the output ports are connected to the innermost metal ring through through holes. The line width and line spacing of the primary and secondary coils are the same.

[0041] The primary and secondary coils of the interleaved transformer are drawn separately, and then the wiring is arranged. First, the shape and size of the innermost polygon are determined. Then, based on the transformer's line width and line spacing, the polygon's edges are translated and intersected to obtain the coordinates of each metal vertex segment. Finally, the input and output ports are adjusted.

[0042] The following is a detailed description of the automatic drawing method of the interleaved winding transformer. The specific drawing includes the following steps:

[0043] Step 101: Determine the position of each vertex in the inner circle. For the convenience of representation, polar coordinates are used. For example, the inner circle of the regular n-gon has an inner diameter of D. in , taking the lower left corner of the regular polygon as the first vertex and counting counterclockwise, the polar diameters of each vertex are:

[0044]

[0045] The angular coordinates of each point are:

[0046]

[0047] Thus, the vertex polar coordinates (R,θ i ). Then convert it into rectangular coordinates, we can get the coordinates of each vertex of the innermost polygon a1=[x1,y1],a2=[x2,y2],…,a n =[x n ,y n ].

[0048] Step 102: Calculate the equations of the lines on each side of the inner polygon. Starting from the first vertex, connect in a counterclockwise order to obtain the equations of the lines on each side of the inner polygon:

[0049] k1x+k2y+k3=0

[0050] where k1 = y i+1 -y i ,k2=x i -x i+1 ,k3=x i+1 y i -x i y i+1 ,i=1,2,...,n. Similarly, we can get the unit direction vector e of each side i :

[0051]

[0052] e u Rotate 90 degrees clockwise to get the unit normal vector t of each side u :

[0053] t i =e i ·T

[0054] in, is a 90 degree rotation matrix.

[0055] Step 103: Translate the above-mentioned straight lines and intersect them to obtain the coordinates of the vertices of the primary and secondary coils of the transformer. Taking the sides of the inner polygon as the basis, since the sides of the coil are parallel to the sides of the inner polygon, the remaining sides of the primary and secondary coils can be obtained by translating the unit direction vectors of each side along the unit normal vector and intersecting them. The translation distance is related to the line width and line spacing of the transformer. Assuming that the straight line translation vector is p = [m, n], and p is along the direction of the unit normal vector, the equation of the straight line after translation is

[0056] k1(xm)+k2(yn)+k3=0

[0057] After obtaining the translated sides, the outer circle vertices can be obtained by intersecting the new straight lines in pairs.

[0058] Step 104: Adjust the coordinates of the input and output ports and connect them according to the vertex coordinates to obtain the metal segments of the transformer. Because the transformer has multiple inner and outer turns, a single layer of metal cannot complete all the wiring. The innermost turn port requires a lower layer of metal lead to the outer side for convenient subsequent connection and use. To account for metal losses and parasitic effects caused by the closely spaced metal conductors, the positions of the inner turn vertices were adjusted when designing the input and output ports of the primary and secondary coils.

[0059] The primary and secondary coils of a symmetrical interwound transformer are wound in parallel on the same metal layer, arranged symmetrically along the axis. The input and output ports of the primary coil are directly connected to the outermost metal ring, while the input and output ports of the secondary coil are connected to the outermost metal ring via through-holes. The line width and line spacing of the primary and secondary coils are the same. The primary and secondary coils of a symmetrical interwound transformer are drawn separately. After the transformer outline is drawn based on the innermost polygon, the coil is divided into two symmetrical parts by the midpoint. The order of connecting the metal segments is then determined. Finally, the two symmetrical metal parts are bridged in sequence, and the cross-tracing sections are drawn.

[0060] The following is a detailed description of the automatic drawing method for a symmetrical interwinding transformer. The specific drawing includes the following steps:

[0061] Step 201: Referring to steps 101 to 103, draw the transformer prototype based on the innermost polygon. un Calculate the vertices of the inner polygon and determine the line width W, line spacing S, and number of turns N p / N s Then, the unit direction vector e and unit normal vector t of each edge of the inner polygon are calculated according to the formula, and then the vertices of the primary and secondary coils are obtained by translation and intersection, that is, multiple concentric polygons as the prototype of the symmetrical transformer.

[0062] Step 202: Divide the coil into two symmetrical parts by the perpendicular bisector. Calculate the coordinates of the upper and lower midpoints from the vertex coordinates of the inner polygon to obtain the perpendicular bisector equations of the upper and lower sides.

[0063] Step 203: Determine the order of metal connection. Divide the coil into two parts, left and right, and sequentially number each section of metal from the outside to the inside and distinguish the head and tail. The left coil has the head on top and the tail on the bottom, and the right coil has the head on the bottom and the tail on the top. When drawing the crossover trace, always go from the head to the tail, that is, the head of the previous section of metal is connected to the tail of the next section of metal, and confirm which two ends of metal are connected in a certain order. First, set the trace flag flag. A flag of 1 indicates inward trace, and a flag of -1 indicates outward trace. The initial flag is 1. Start with the metal segment numbered 1, and then discuss each case. If the current metal number is not equal to 2, continue to judge the flag. If flag is 1 and the current coil is in the innermost coil, the current metal segment's head is connected to the end of the other half of the coil, the number is updated, and the flag bit is set to -1. If flag is 1 and the current coil is not in the innermost coil, the current metal segment's head is connected to the end of the other half of the inner coil, and the number is updated. If flag is -1, the current metal segment's head is connected to the end of the other half of the outer coil, and the number is updated. For common coil turns, the order of metal connections can also be pre-stored according to the numbering rules.

[0064] Step 204: Create a bridge between the two symmetrical metal sections and draw the crossover traces. The basic idea is to translate the endpoints from the midpoint of each side to the left and right, leaving space for the bridge to form new endpoints. These are then connected according to the sequence in step 203. To meet the angular requirements of chip design, an isosceles triangle is used for endpoint translation. The translated coordinates are then calculated based on the unit direction vectors of each side to complete the automatic drawing.

[0065] The automated drawing method for a symmetrical stacked transformer is similar to that for a symmetrical interwound transformer. Its primary and secondary coils are wound parallel to each other on multiple metal layers, arranged axially symmetrically. The primary coil's input and output ports are directly connected to the outermost metal ring, while the secondary coil's input and output ports are connected to the outermost metal ring via vias. The primary and secondary coils have the same trace width and spacing. For some common coil turns ratios, the order of connections between metal layers, within layers, and between layers can be pre-set. During the drawing process, cross-tracing and interlayer via design are performed according to pre-set rules.

[0066] In some embodiments, the on-chip transformer automatic drawing method further includes tap drawing, adding the metal segment number and metal relative position parameters of the tap to the above drawing method. First, the positions where the transformer can add taps are divided and numbered. In the staggered interwinding transformer, the tap can be assigned to the entire area. In the symmetrical interwinding transformer and the symmetrical stacked transformer, the tap can be assigned to the area excluding the cross-tracing part. The relative position is evenly distributed from one port of the coil to the other in the counterclockwise direction, ranging from 0 to 1, and gradually increases along the metal direction. The middle position is 0.5, that is, the center tap, which is a more common tap position choice.

[0067] During the automated modeling and drawing of transformers, area constraints are particularly important, as chip size and cost are closely related. Especially for passive components such as on-chip inductors and on-chip transformers, in addition to their own area, attention must also be paid to the interference that the inductors and transformers may cause to other components. A common practice is to reserve space for other modules or add additional isolation modules, which results in a larger actual area. Therefore, the area of ​​the transformer should be minimized. The area of ​​the transformer is directly related to its inner diameter, but an excessively small inner diameter can lead to incorrect modeling of the inner coil (especially for octagonal transformers), thus affecting the overall modeling effect.

[0068] In some embodiments, the geometric prior knowledge is combined to pre-screen the drawn structure, which can effectively improve the modeling success rate, and the automatic modeling success rate can reach 100%. Assume that the transformer line width is W, the line spacing is S, and the inner diameter is D in , the cross trace width is W Bridge , the port width is W Port , and the upper and lower layer through-hole width is W ViaTo ensure correct modeling, the centerline should be shifted to the left and right to create a "bridge" so that the inner side of the metal segment does not reach the inflection point, and the outer side of the metal segment should not reach the inflection point after adding a through hole. If the number of turns of the primary and secondary coils is different, it should also be ensured that the "bridge" and the lead-out ports do not reach the inflection point. Otherwise, the input and output ports and internal coils may fold. Specific constraints need to be discussed based on the transformer structure and the number of turns of the primary and secondary coils.

[0069] The structural parameters of the symmetrical same-layer n:n quadrilateral transformer must meet the following requirements:

[0070]

[0071] The structural parameters of the symmetrical same-layer n:n octagonal transformer must meet the following requirements:

[0072]

[0073] Symmetrical same-layer 1:2, 2:3, 2:1, 3:2 quadrilateral transformer structural parameters must meet the following requirements:

[0074]

[0075] Symmetrical same-layer 1:2, 2:3, 2:1, 3:2 octagonal transformer structural parameters must meet the following requirements:

[0076]

[0077] The structural parameters of the symmetrically stacked 1:1 quadrilateral transformer must meet the following requirements:

[0078]

[0079] The structural parameters of the symmetrically stacked 1:1 octagonal transformer must meet the following requirements:

[0080]

[0081] The structural parameters of the symmetrical stacked 2:2 quadrilateral transformer must meet the following requirements:

[0082]

[0083] The structural parameters of the symmetrically stacked 2:2 octagonal transformer must meet the following requirements:

[0084]

[0085] The structural parameters of the symmetrically stacked 1:2 and 2:1 quadrilateral transformers must meet the following requirements:

[0086]

[0087] The structural parameters of the symmetrically stacked 1:2 and 2:1 octagonal transformers must meet the following requirements:

[0088]

[0089] Among them, △ is the spacing between ports and through holes caused by the need to meet chip design rules when crossing routing, which can be freely adjusted.

[0090] The following describes the automatic on-chip transformer drawing method by combining two design examples of an interleaved interwinding transformer and a symmetrical interwinding transformer.

[0091] Example 1: Automatic drawing of interlaced quadrilateral transformer

[0092] Step 301: Determine the positions of the vertices of the inner circle. For convenience, polar coordinates are used, with the lower left corner of the quadrilateral as the first vertex. Counting counterclockwise, the coordinates are then converted to rectangular coordinates. The coordinates of the vertices of the inner quadrilateral are: A = [x1, y1], B = [x2, y2], C = [x3, y3], and D = [x4, y4].

[0093] Step 302: Calculate the equations of the lines on each side of the inner polygon:

[0094] l AB :a1x+b1y+c1=0,a1=y2-y1,b1=x1-x2,c1=x2y1-x1y2

[0095] l BC :a2x+b2y+c2=0,a2=y3-y2,b2=x2-x3,c2=x3y2-x2y3

[0096] l CD :a3x+b3y+c3=0,a3=y4-y3,b3=x3-x4,c3=x4y3-x3y4

[0097] l DA :a4x+b4y+c4=0,a4=y1-y4,b4=x4-x1,c4=x1y4-x4y1

[0098] The unit direction vectors of each side and the normal unit direction vector:

[0099]

[0100] t AB =e AB ·T,t BC =e BC ·T,t CD =e CD ·T,t DA =e DA ·T

[0101] The vectors of the inner circle are drawn as follows Figure 1 shown.

[0102] Step 303: Translate the above-mentioned straight lines and intersect them to obtain the coordinates of the vertices of the primary and secondary coils of the transformer. The translation distance is determined by the line width W and the line spacing S. Figure 2 (a) shows the calculation process of the first vertex of the primary coil. Points A and B are the first and second vertices on the inner side of the metal. in1 、b in1 , straight line l 11 By l AB It can be obtained by translating along the vector p2. It only needs to move a distance of line width. The straight line l DA and straight line l 11 Intersect to get the first vertex a on the outside of the metal out1 Straight line l BC The straight line l is obtained by translating a line width in the direction of the normal vector 21 , and l 11 Intersect at the second vertex b on the outside out1 Straight line l CD Translate along vector p1 to get straight line l 31 , that is, translate the distance of one line width plus one line distance, leaving space in the middle to distribute the secondary coil, straight line l BC and straight line l 31 Intersect to get the third vertex c on the inside of the metal in1 Straight line l 31 Continue translating along the direction of p1 by a line width to obtain the straight line l 32 , and l 21 Intersect at the third vertex c on the outside out1 Straight line l DA The straight line l is obtained by translating the normal vector outward by a line width plus a line distance. 41 , l 41 and straight line l 31 The fourth vertex d that intersects the inside in1 , and then continue to translate a line width to get the straight line l 42 Straight line l 42 and straight line l 32 Intersect to get the fourth vertex d on the outside out1 A coil of four metal segments needs to be surrounded by five vertices inside and outside. To get the fifth vertex inside and outside, the first segment of the second circle is needed. 11 Translate along vector p3 to get straight line l 12 , that is, translate by a line width plus twice the line spacing, leaving space for the secondary coil, straight line l 12 and l 41 Intersect to get the first vertex a of the second inner circle in . l12 Continue to translate outward a line width to get straight line l 13 , intersecting line l 42 At the first vertex a of the second circle on the outside out2 . Among them, the translation vectors are as follows:

[0103] p1=(W+S)t CD =[m1,n1]

[0104] p2=Wt AB =[m2,n2]

[0105] p3=(W+2S)t AB =[m3,n3]

[0106] Then the straight line l 11 The equation is:

[0107] a1(x-m2)+b1(y-n2)+c2=0

[0108] By analogy, the equations of each straight line and the coordinates of each vertex of the initial coil can be obtained.

[0109] After obtaining the vertex coordinates, you can use the SKILL script to call VIRTUOSO to generate metal Figure 2 A similar method can be used to automatically draw the secondary coil metal as shown in (b). Figure 3 As shown in (a), the first port inside and outside the primary and secondary coils are connected to the adjacent metal, which will cause short circuit and other losses, so its coordinates are adjusted to Figure 3 (b) The specific end position can be determined according to the number of turns. It is worth noting that the end port position of the coil should also avoid connection with other metals.

[0110] The final interlaced quadrilateral transformer is drawn as follows Figure 4 shown.

[0111] Example 2: Automatic drawing of symmetrical interwinding quadrilateral transformer

[0112] Step 401: Draw the transformer prototype based on the innermost polygon. in Determine the coordinates of each vertex of the inner quadrilateral A=[x1,y1], B=[x2,y2], C=[x3,y3], D=[x4,y4], and calculate the equations of each side, the unit direction vector, and the unit normal vector. The remaining lines are obtained by translation, such as Figure 5 There are two types of translation vectors. One is the inner and outer sides of the same piece of metal, which need to be translated by a line width, such as Figure 5 In p1, the second case needs to cross the metal of the secondary coil and needs to be translated by a distance of twice the line width plus the line spacing, such as Figure 5The intersection of the lines yields the coordinates of the metal's vertices. Thus, a series of concentric quadrilaterals forms the prototype of a symmetrical transformer.

[0113] p1=Wt AB =[m1,n1]

[0114] p2=2×(W+S)t AB =[m2,n2]

[0115] Step 402: Calculate the perpendicular bisector equation from the coordinates of the midpoints of the upper and lower sides, and divide the coil into two parts, Figure 6 The diagram shows the symmetrical primary and secondary coils after being split but not yet crossing the lines. The metal on both sides will then shift horizontally from the midline to the sides.

[0116] Step 403: Determine the metal connection order. Number the metal on the left and right sides respectively. Figure 7 The primary coil metal numbering is shown. The primary and secondary coils are numbered separately and bridged. When the number of turns is 2:2, the metal connection order is 1→4→3→2.

[0117] Step 404: "Bridge" the two symmetrical metal parts and draw the cross-wiring part. The basic idea is to translate the endpoints from the midpoint of each side to the left and right sides, reserve space for the bridge, form new endpoints, and then connect them in the order of step 403. In order to meet the angle requirements of the chip design rules, an isosceles triangle is used to translate the endpoints, and then the coordinates after translation are calculated based on the unit direction vector of each side to complete the automatic drawing. It should be noted that the main metal part is in the same metal layer, and the routing part needs to transition in other layers. The more turns, the more layers are used. When the number of turns is 2:2, at least three layers of metal are required. The middle layer is used for the distribution of the metal body, and the upper and lower layers are used for routing.

[0118] like Figure 8 Take the cross-line part shown as an example, point M is the middle point on the top, L and M R The two translation vectors p3 and p4 can be obtained from the unit direction vector of the CD side. The routing after translation should comply with the chip design rules. The isosceles triangle shown in the figure can ensure 45-degree routing. Considering that the adjacent metals belong to two coils, the length of the right angle side is twice the line width plus twice the line spacing, as shown in the figure. Figure 9 As shown,

[0119] p3=-2×(W+S)e CD

[0120] p4=2×(W+S)e CD

[0121] The coordinates of point M are known, so we can find M Land M R The coordinates of the point are calculated, and the left and right vertices of other crossover lines are obtained by analogy. After the coordinates are calculated, call VIRTUOSO to generate the layout as shown below Figure 10 As shown, the input and output ports of the primary and secondary coils have been repositioned to prevent short circuits and facilitate cascading. The secondary coil ports are connected via lower-layer leads. Metal is connected sequentially according to numbering, and metal layers are allocated based on the distribution of crossover traces to avoid overlapping "bridges."

[0122] Figure 11 Various on-chip transformer structure diagrams automatically drawn based on the method of the present invention are illustrated.

[0123] An embodiment of the present invention further discloses a computer program product comprising a computer program / instructions that, when executed by a processor, implement the steps of the method for automatically drawing an on-chip transformer. The program / instruction code for implementing the method of the present invention can be written in any combination of one or more programming languages. These program / instruction codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the processor or controller, the program / instruction code implements the steps of the method of the present invention. The program / instruction code can be executed entirely on the machine, partially on the machine, partially on the machine as a standalone software package and partially on a remote machine, or entirely on a remote machine or server.

[0124] Anything not described in detail in the present invention is well known to those skilled in the art.

[0125] In summary, the foregoing is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for automatically drawing an on-chip transformer, characterized in that: The steps include: Obtain on-chip transformer structural parameters, including inner ring polygon shape, inner diameter, line width, line spacing, and number of turns; Determine the positions of the vertices of the inner circle, and the unit direction vector and unit normal vector of each side of the inner circle polygon according to the shape and inner diameter of the inner circle polygon; The vertices of the primary and secondary coils are obtained by translating the unit direction vectors of each side along the unit normal vector and intersecting them. The translation distance is determined according to the line width and line spacing of the transformer. Adjust the coordinates of input and output ports and arrange the wiring; The drawn structure is pre-screened based on geometric prior knowledge, and specific constraints are determined according to the transformer structure and the number of primary and secondary coil turns to ensure correct modeling. These constraints include: the inner side of the metal segment does not reach the inflection point after the center line is translated to the left and right to bridge the gap; the outer side of the metal segment does not reach the inflection point after adding a through hole; and when the number of primary and secondary coil turns is different, the bridge should be built and the inflection point should not be reached after the lead-out port.

2. The method for automatically drawing an on-chip transformer according to claim 1, wherein: Determine the position of each vertex in the inner circle based on the number of sides and inner diameter, including: using polar coordinates to determine the polar diameter of each vertex and angular coordinates Get the vertex polar coordinates (R,θ i ), and then converted to rectangular coordinates; where D in is the inner diameter, n is the number of sides of the regular polygon; The rectangular coordinates are used to calculate the equations of the lines forming the edges between the adjacent vertices, thereby obtaining the unit direction vector and the unit normal vector of each edge.

3. The method for automatically drawing an on-chip transformer according to claim 1, wherein: The on-chip transformer is an interleaved interwound transformer, in which the primary coil and the secondary coil are interleaved and wound on the same metal layer and are centrally symmetrically distributed; the input ports of the two-pole coils are connected to the outermost metal ring, and the output ports are connected to the innermost metal ring via through holes; the line width and line spacing of the primary coil and the secondary coil are the same.

4. The method for automatically drawing an on-chip transformer according to claim 1, wherein: The on-chip transformer is a symmetrical interwinding transformer, in which the primary coil and secondary coil are wound in parallel on the same metal layer and are axially symmetrically distributed; the input and output ports of the primary coil are directly connected to the outermost metal circle, and the input and output ports of the secondary coil are connected to the outermost metal circle via through holes; the line width and line spacing of the primary coil and the secondary coil are the same.

5. The method for automatically drawing an on-chip transformer according to claim 4, wherein: The primary and secondary coils of the symmetrical interwinding transformer are drawn separately. After the transformer prototype is drawn based on the innermost polygon, the coil is divided into two symmetrical parts by the median line. Then the connection order of the metal segments is determined. Finally, the two symmetrical parts of metal are bridged in sequence to draw the cross-wiring part.

6. The method for automatically drawing an on-chip transformer according to claim 5, characterized in that: Determining the metal segment connection order includes: Divide the coil into two parts, left and right. Number each section of metal sequentially from the outside to the inside and distinguish the head and tail. Remember that the left coil has the head on top and the tail below, and the right coil has the head below and the tail on top. When drawing the crossover traces, always go from the head to the tail. Set the routing flag flag. A flag of 1 indicates inward routing, and a flag of -1 indicates outward routing. The initial flag is 1. Start from the metal segment labeled 1 and discuss each case. If the current metal label is not equal to 2, continue to judge the flag. If the flag is 1 and the current metal segment is in the innermost circle, connect the head of the current metal segment to the tail of the other half of the innermost circle, update the label, and update the flag flag to -1. If the flag is 1 and the current metal segment is not in the innermost circle, connect the head of the current metal segment to the tail of the other half of the inner circle and update the label. If the flag is -1, connect the head of the current metal segment to the tail of the other half of the outer circle and update the label.

7. The method for automatically drawing an on-chip transformer according to claim 1, wherein: The on-chip transformer is a symmetrical stacked transformer, whose primary and secondary coils are wound in parallel on multiple metal layers and are distributed axially symmetrically; the input and output ports of the primary coil are directly connected to the outermost metal ring, and the input and output ports of the secondary coil are connected to the outermost metal ring via through holes; the line width and line spacing of the primary and secondary coils are the same.

8. The method for automatically drawing an on-chip transformer according to claim 1, wherein: It also includes transformer tap drawing, first determining the metal segment number of the tap, and then determining the metal relative position parameters; in an interleaved interwinding transformer, the tap can be assigned to the entire area, and in a symmetrical interwinding transformer and a symmetrical stacked transformer, the tap can be assigned to the area excluding the cross-wiring part.

9. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the steps of the on-chip transformer automatic drawing method according to any one of claims 1 to 8 are implemented.

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