Automatic drawing method for on-chip transformer

Abstract

The invention discloses an on-chip transformer automatic drawing method which can be suitable for various structures including a staggered mutual winding transformer, a symmetrical mutual winding transformer and a symmetrical laminated transformer. According to the on-chip transformer automatic drawing method, drawing of transformers of any polygons, different structures and multiple turn ratios can be achieved, a tap structure can be additionally arranged at any position, and common radio frequency circuit application scenes can be covered. Compared with traditional manual drawing, the method has the advantages that the transformer layout can be quickly output only by providing required structural parameters and structural types, and the design efficiency of passive devices is greatly improved. Meanwhile, the drawing structure is pre-screened in combination with geometric priori knowledge, and the automatic modeling success rate can reach 100%. According to the method, the success rate is guaranteed, and meanwhile automation and intelligentization of radio frequency circuit design are promoted.

Description

Technical Field

[0001] The 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] The on-chip transformer is an important component of RF integrated circuits. Its shape greatly affects the circuit layout. Due to the lack of accurate and fast performance evaluation technology, it has become one of the bottlenecks in RF and millimeter wave circuit design. From the designer's perspective, the most concerned issues are the performance of the transformer, modeling, and the time consumed to obtain a suitable physical layout, because these greatly affect the design cycle and even the success of tape-out. The transformer models provided by the foundry usually have a limited frequency range and limited accuracy. In some cases, there is no transformer model in the process design kit, or the existing model does not meet the requirements, which makes the design more difficult and requires designers to redesign the transformer.

[0003] Although it is feasible for designers to manually draw transformers, it is very time-consuming, especially when there are multiple turns involved, the routing becomes more difficult, and continuous full-wave electromagnetic simulation is required to iteratively modify parameters, and the layout and area of ​​the entire circuit must also be considered. Automatically drawing transformers on a chip can design a large number of transformers for designers to choose from in a short period of time, while limiting structural parameters, which can greatly improve design efficiency. Summary of the invention

[0004] Purpose of the invention: In view of the problems and shortcomings existing in the prior art, the present invention provides an on-chip transformer automatic drawing method, which can quickly realize the transformer layout generation by only providing structural parameters such as the inner diameter, line width, line spacing, number of turns, etc. of the transformer. Compared with traditional manual structure drawing, it 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] An on-chip transformer automatic drawing method comprises the following steps:

[0007] Obtaining 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 each vertex of the inner circle, as well as the unit direction vector and unit normal vector of each edge of the inner circle polygon according to the shape and inner diameter of the inner circle polygon;

[0009] Each vertex of the primary and secondary coils is 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 straight line equations of the edges formed by adjacent vertices, and then the unit direction vector and the unit normal vector of each edge are obtained.

[0013] Furthermore, the on-chip transformer is an interlaced interwinding transformer, in which the primary coil and the secondary coil are interlaced and wound on the same metal layer and are centrally symmetrically distributed; the input ports of the two-polar 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, in which the primary coil and the 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 midline, and then the connection order of the metal segments is determined. Finally, the two symmetrical parts of metal are bridged in turn to draw the cross-wiring part.

[0016] Furthermore, the determination of the metal segment connection sequence includes:

[0017] Divide the coil into two parts, left and right. Number each section of metal from outside to 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. 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 segment is currently 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 segment is not currently 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 the staggered interwinding transformer, the tap can be assigned to the entire area, and in the symmetrical interwinding transformer and the 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 according to the transformer structure and the number of primary and secondary coil turns to ensure correct modeling, including: the inner side of the metal segment does not reach the inflection point after the center line is translated to the left and right sides to bridge; the outer side of the metal segment does not reach the inflection point after the through hole is added; when the number of primary and secondary coil turns is different, it should be ensured that the bridge is bridged and the inflection point is not reached after the lead-out port.

[0022] A computer program product comprises a computer program / instruction, wherein when the computer program / instruction is executed by a processor, the steps of the on-chip transformer automatic drawing method are implemented.

[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 realize the automatic drawing of the on-chip transformer and output the layout, which greatly improves the work efficiency of RF circuit designers;

[0025] (2) The present invention supports transformer drawing with three structures of arbitrary polygonal interlaced winding, symmetrical winding 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 automatic drawing success rate of the on-chip transformer reaches 100%, promoting the automation and intelligent design of radio frequency circuit design. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the unit direction vectors of each side of the inner circle quadrilateral and the unit direction vector of the normal;

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

[0029] Figure 3 This is a schematic diagram of the comparison 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 It is the prototype of the symmetrically 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 symmetrically wound quadrilateral transformer;

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

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

[0037] Fig.11 Automatically draw example diagrams of structures for various on-chip transformers. DETAILED DESCRIPTION

[0038] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0039] An embodiment of the present invention discloses an on-chip transformer automatic drawing method, and the main steps 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, and the unit direction vector and unit normal vector of each side of the inner circle polygon according to 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 line width and line spacing of the transformer; and finally, adjusting the coordinates of the input and output ports and arranging the wiring.

[0040] The method of the embodiment of the present invention can be applied 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 coil and the secondary coil 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-pole coils are connected to the outermost circle of metal, and the output ports are connected to the innermost circle of metal through through holes; the line width and line spacing of the primary coil and the secondary coil are the same.

[0041] The primary and secondary coils of the interlaced transformer are drawn separately, and then the wiring is arranged. First, the shape and size of the innermost polygon are determined, and then the edges of the polygon are translated and intersected according to the line width and line spacing of the transformer to obtain the coordinates of the metal vertices of each segment, and finally the input and output ports are adjusted.

[0042] The following is a detailed description of the automatic drawing method of the interlaced winding transformer, which includes the following steps:

[0043] Step 101: Determine the position of each vertex of the inner circle. For the convenience of representation, polar coordinates are used. For example, the inner circle of a regular n-gon with 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 the vertices 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 straight line equations of each side of the inner circle polygon. Starting from the first vertex, connect in a counterclockwise order to obtain the straight line equations of each side of the inner circle 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 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 circle polygon as the basis, since the sides of the coil are parallel to the sides of the inner circle polygon, the remaining sides of the primary and secondary coils can be obtained by translating the unit direction vectors of the sides 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 translation vector of the straight line is p = [m, n], p is along the direction of the unit normal vector, then 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 the metal segments of the transformer according to the vertex coordinates. Because the transformer has multiple inner and outer coils, it is impossible to complete all the wiring with only one layer of metal. The innermost ring port needs the lower layer of metal lead to the outside to facilitate subsequent connection and use. At the same time, considering the metal loss and parasitic effects caused by the small distribution spacing of the metal conductor, the position of the inner ring vertex is adjusted when designing the input and output ports of the primary and secondary coils.

[0059] The primary and secondary coils of the symmetrical interwinding transformer 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 through through holes; the line width and line spacing of the primary and secondary coils are the same. 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 midpoint, and the order of connecting the metal segments is determined. Finally, the two symmetrical parts of metal are bridged in turn, and the cross-wiring part is drawn.

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

[0061] Step 201: Referring to steps 101 to 103, draw the transformer prototype according to 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 circle 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 midpoints of the upper and lower sides by the coordinates of the vertices 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 number each section of metal from the outside to the inside in sequence 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 part is in the innermost circle, the head of the current metal segment is connected to the tail of the other half of the circle, the number is updated, and the flag is updated to -1; if flag is 1 and the current part is not in the innermost circle, the head of the current metal segment is connected to the tail of the other half of the inner circle, and the number is updated; if flag is -1, the head of the current metal segment is connected to the tail of the other half of the outer circle, and the number is updated. For common coil turns, the order of metal connection can also be pre-stored according to the numbering rules.

[0064] Step 204: The two symmetrical metal parts are "bridged" to draw the cross-line part. The basic idea is to translate the endpoints from the midpoint of each side to the left and right sides, reserve the space for the bridge, form new endpoints, and then connect them according to the order of step 203. In order to meet the angle requirements of chip design, an isosceles triangle is used to translate the endpoints, and then the coordinates after translation are calculated according to the unit direction vector of each side to complete the automatic drawing.

[0065] The automatic drawing method of symmetrical stacked transformer is similar to that of symmetrical interwinding transformer. Its 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 metal circle, and the input and output ports of the secondary coil are connected to the outermost metal circle through through holes. The line width and line spacing of the primary coil and the secondary coil are the same. For some common coil turns ratios, the connection sequence between the metal layers used, the metal segments within the layer and between the layers can be pre-set. When drawing, cross routing and interlayer through-hole design are performed according to preset 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 an interleaved interwinding transformer, the tap can be assigned to the entire area. In a symmetrical interwinding transformer and a symmetrical stacked transformer, the tap can be assigned to the area except the cross-wiring portion. The relative position is evenly distributed from 0 to 1 in the counterclockwise direction from one port of the coil to the other, gradually increasing along the metal direction, and the middle position is 0.5, that is, the center tap, which is a more common tap position choice.

[0067] In the process of automatic transformer modeling and drawing, area limitation is particularly important, and chip size is closely related to cost. Especially for passive devices such as on-chip inductors and on-chip transformers, in addition to their own area, attention must also be paid to the interference caused by inductors and transformers to other devices. A common practice is to reserve space for other modules in advance or to add additional isolation modules, so the actual occupied area will be larger, so the area of ​​the transformer should be reduced as much as possible. The area of ​​the transformer is directly related to the inner diameter, but a too small inner diameter will lead to modeling errors of the inner coil (especially for octagonal transformers), which will affect 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 width of the upper and lower through holes is W Via. To ensure correct modeling, the center line should be translated to the left and right sides so that the inner side of the metal segment does not reach the inflection point after "bridging", and the outer side of the metal segment does not reach the inflection point after adding a through hole. When the number of turns of the primary and secondary coils is different, it should also be ensured that the inflection point is not reached after "bridging" and the lead-out port, otherwise the input and output ports and the internal coil may be folded. Specific constraints need to be discussed according to 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] The structural parameters of symmetrical same-layer 1:2, 2:3, 2:1, 3:2 quadrilateral transformers must meet the following requirements:

[0074]

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

[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 symmetrically 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 adjusted freely.

[0090] The following is an illustrative description of 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 position of each vertex of the inner circle. For the convenience of representation, polar coordinates are used, with the lower left corner of the quadrilateral as the first vertex, counting counterclockwise, and then converted to rectangular coordinates, then the coordinates of the vertices of the inner circle quadrilateral are: A = [x1, y1], B = [x2, y2], C = [x3, y3], D = [x4, y4].

[0093] Step 302: Calculate the straight line equations of the inner polygon sides:

[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 are:

[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 Figure 1 shown.

[0102] Step 303: The above straight lines are translated and intersected 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 distance 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 vector p2. It only needs to move a distance of line width. 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 Translate along the normal vector direction by a line width to obtain the straight line l 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 by a line width plus a 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 inner side 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 .12 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 is 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 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 the vertices of the inner quadrilateral A=[x1,y1], B=[x2,y2], C=[x3,y3], D=[x4,y4], calculate the equations of the lines, the unit direction vectors and the unit normal vectors of the sides. 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 5p2 in the figure. The straight lines intersect to obtain the coordinates of each metal vertex. So far, a series of concentric quadrilaterals form 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 equation of the perpendicular bisector from the coordinates of the midpoints of the upper and lower sides, and divide the coil into two parts, left and right. Figure 6 The symmetrical primary and secondary coils are shown after being split but not yet crossed. The metal on both sides will then move horizontally from the midline to both sides.

[0116] Step 403: Determine the metal connection sequence. Number the metals on the left and right sides respectively. Figure 7 The numbering of the primary coil metal is shown. The primary and secondary coils are numbered separately and cross-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 parts of metal and draw the crossover routing 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 vectors 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 crossover wiring section 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, and 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, such as Fig. 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 points are calculated by analogy, and the left and right vertices of other crossing lines are obtained. After the coordinates are calculated, call VIRTUOSO to generate the layout as shown below Fig.10 As shown in the figure, the input and output port positions of the primary and secondary coils are adjusted to prevent short circuits and facilitate cascading. The secondary coil ports are led out through the lower layer leads. The metal is connected in sequence according to the number, and the metal layer is allocated according to the distribution of the cross-wires to avoid the overlap of the "bridge".

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

[0123] The embodiment of the present invention also discloses a computer program product, including a computer program / instruction, which implements the steps of the on-chip transformer automatic drawing method when executed by a processor. 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, so that the program / instruction code, when executed by the processor or controller, 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 stand-alone software package and partially on a remote machine, or entirely on a remote machine or server.

[0124] The matters not described in detail in the present invention are all known technologies to those skilled in the art.

[0125] In summary, the above is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for automatically drawing an on-chip transformer, characterized in that: The steps include: Obtaining on-chip transformer structural parameters, including inner ring polygon shape, inner diameter, line width, line spacing, and number of turns; Determine the positions of each vertex of the inner circle, as well as the unit direction vector and unit normal vector of each edge of the inner circle polygon according to the shape and inner diameter of the inner circle polygon; Each vertex of the primary and secondary coils is 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 input and output port coordinates and arrange the wiring.

2. The on-chip transformer automatic drawing method according to claim 1, characterized in that: Determining the positions of the vertices of the inner circle according to the number of edges and the inner diameter includes: determining the polar diameter of each vertex using polar coordinates 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 straight line equations of the edges formed by adjacent vertices, and then the unit direction vector and the unit normal vector of each edge are obtained.

3. The on-chip transformer automatic drawing method according to claim 1, characterized in that: The on-chip transformer is an interlaced interwinding transformer, in which the primary coil and the secondary coil are interlaced and wound on the same metal layer and are centrally symmetrically distributed; the input ports of the two-polar 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.

4. The on-chip transformer automatic drawing method according to claim 1, characterized in that: The on-chip transformer is a symmetrical inter-wound transformer, in which the primary coil and the 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.

5. The on-chip transformer automatic drawing method according to claim 4, characterized in that: 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 midline, and then the connection sequence 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 on-chip transformer automatic drawing method according to claim 4, characterized in that: The determination of the metal segment connection sequence includes: Divide the coil into two parts, left and right. Number each section of metal from outside to 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 segment is currently 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 segment is not currently 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 on-chip transformer automatic drawing method according to claim 1, characterized in that: The on-chip transformer is a symmetrical laminated 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.

8. The on-chip transformer automatic drawing method according to claim 1, characterized in that: 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 except the cross-wiring part.

9. The on-chip transformer automatic drawing method according to claim 1, characterized in that: The method combines geometric prior knowledge to pre-screen the drawn structure, and determines specific constraints according to the transformer structure and the number of turns of the primary and secondary coils to ensure correct modeling, including: the inner side of the metal segment does not reach the inflection point after the midline is translated to the left and right sides to bridge; the outer side of the metal segment does not reach the inflection point after the through hole is added; when the number of turns of the primary and secondary coils are different, it should be ensured that the bridge is bridged and the inflection point is not reached after the lead-out port.

10. 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 9 are implemented.

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