Automatic layout generation method for on-chip transformers

Abstract

Disclosed in the present invention is an automatic layout generation method for on-chip transformers, which method is applicable to various structures, including interleaved interwound transformers, symmetrical interwound transformers, and symmetrical stacked transformers. The automatic layout generation method for on-chip transformers in the present invention can implement the layout generation of transformers having any polygonal shapes, different structures and various turn ratios, can add a tap structure at any position, and can cover common radio-frequency circuit application scenarios. Compared with the conventional manual layout generation, the present invention can quickly output transformer layouts as long as the required structural parameters and structural types are provided, thereby greatly improving the design efficiency of passive devices. Moreover, the present invention integrates geometric prior knowledge to pre-screen layout generation structures, such that the success rate of automatic modeling can reach 100%. The method of the present invention promotes the automation and intellectualization of radio-frequency circuit design while ensuring the success rate.

Description

Automatic drawing method of on-chip transformer TECHNICAL FIELD

[0001] The application relates to an automatic drawing method of an on-chip transformer, which can quickly realize structure modeling relative to traditional manual drawing, and belongs to the field of radio frequency passive devices. BACKGROUND

[0002] The on-chip transformer is an important component of a radio frequency integrated circuit, and its shape greatly influences circuit layout. Due to the lack of accurate and fast performance evaluation technology, the on-chip transformer has become one of the bottlenecks in the design of radio frequency and millimeter wave circuits. From the perspective of designers, the most concerned problems are the performance of the transformer, the time consumed for modeling and obtaining a suitable physical layout, because these greatly influence the design cycle and even the success of tape-out. The transformer model provided by a foundry usually has a limited frequency range and limited precision, and 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 the designer to redesign the transformer.

[0003] Although the transformer can be manually drawn by the designer, it is very time-consuming, especially when the wiring difficulty is increased when a plurality of turns are involved, and constant full-wave electromagnetic simulation is required to iteratively modify parameters, and the layout and area of the entire circuit also need to be considered. The automatic drawing of the on-chip transformer can design a large number of transformers for the designer to select in a short time, and the structure parameters are limited, which can greatly improve the design efficiency. SUMMARY

[0004] The application provides an automatic drawing method of an on-chip transformer, which can quickly realize transformer layout generation by only providing structure parameters such as the inner diameter, line width, line spacing and turn number of the transformer, and greatly improves the work efficiency of radio frequency circuit designers compared with traditional manual structure drawing.

[0005] Technical scheme: in order to achieve the above purpose, the technical scheme adopted by the application is:

[0006] The automatic drawing method of the on-chip transformer comprises the following steps:

[0007] Obtaining the structure parameters of the on-chip transformer, including the inner circle polygon shape, the inner diameter, the line width, the line spacing and the turn number;

[0008] According to the inner circle polygon shape and the inner diameter, the positions of the vertices of the inner circle, the unit direction vector and the unit normal vector of each edge of the inner circle polygon are determined;

[0009] The primary and secondary coil vertices are obtained by translating the unit direction vector of each edge along the unit normal vector to intersect, and the translation distance is determined according to the transformer line width and line spacing.

[0010] Adjusting and arranging the input and output port coordinates.

[0011] Further, the method for determining the position of each vertex of the inner circle according to the number of sides and the inner diameter comprises: determining the polar radius and the angle coordinate of each vertex by using polar coordinates and angle coordinates to obtain vertex polar coordinates (R, θ i ), and then converting the polar coordinates into rectangular coordinates; wherein D in is the inner diameter, and n is the number of sides of the regular polygon.

[0012] The method further comprises: calculating the straight line equation of the side formed by the adjacent vertices, and then obtaining the unit direction vector and the unit normal vector of each side.

[0013] Further, the on-chip transformer is a staggered mutual-winding transformer, the primary coil and the secondary coil of which are staggered and wound in the same metal layer and are centrally symmetrically distributed; the input port of the two coils is connected with the outermost metal, and the output port is connected with the innermost metal through a via hole; the line width and the line spacing of the primary coil and the secondary coil are the same.

[0014] Further, the on-chip transformer is a symmetric mutual-winding transformer, the primary coil and the secondary coil of which are parallel wound in the same metal layer and are axially symmetrically distributed; the input and output ports of the primary coil are directly connected with the outermost metal, and the input and output ports of the secondary coil are connected with the outermost metal through a via hole; the line width and the line spacing of the primary coil and the secondary coil are the same.

[0015] Further, the primary and secondary coils of the symmetric mutual-winding transformer are drawn respectively, the transformer prototype is drawn according to the innermost polygon, the coils are divided into two left and right symmetric parts by the median line, the connection order of the metal segments is determined, and finally the left and right symmetric metal segments are bridged in sequence to draw the cross-wiring part.

[0016] Further, the determination of the connection order of the metal segments comprises:

[0017] The coils are divided into two left and right parts, each metal segment is sequentially numbered from outside to inside and is distinguished as a head and a tail; the upper part of the left coil is the head and the lower part is the tail, and the lower part of the right coil is the head and the upper part is the tail; when drawing the cross-wiring, the head is always connected to the tail.

[0018] A wire marking flag bit flag is set, flag is 1 and indicates that wire is inwards, flag is -1 and indicates that wire is outwards, initial flag is 1;From the metal segment of label 1, case is discussed, if current metal label is not equal to 2, continue to judge flag bit, flag is 1 and current is in the innermost circle, connect the head of current metal segment with the tail of the other half of the circle, update label, and update flag bit flag as -1;If flag is 1 and current is not in the innermost circle, connect the head of current metal segment with the tail of the other half of the circle, update label;If flag is -1, connect the head of current metal segment with the tail of the other half of the circle, update label.

[0019] Further, the on-chip transformer is a symmetric laminated transformer, the primary coil and the secondary coil of which are parallel wound in multiple metal layers and axially symmetrically distributed;The input and output ports of the primary coil are directly connected with the outermost metal, and the input and output ports of the secondary coil are connected with the outermost metal through a via hole;The line width and line spacing of the primary coil and the secondary coil are the same.

[0020] Further, the method further comprises transformer tap drawing, first determining the metal segment number of the tap, and then determining the metal relative position parameter;In the interleaved mutual winding transformer, the tap assignable position is the whole area, and in the symmetric mutual winding transformer and the symmetric laminated transformer, the tap assignable position is the area except the cross-wire part.

[0021] Further, the method combines geometric prior knowledge to pre-screen the drawing structure, and determines specific constraints to ensure correct modeling according to the transformer structure form and the primary and secondary coil turn numbers, including: the inner side of the metal segment after the middle line is translated to the left and right sides and bridged does not reach the inflection point;The outer side of the metal segment after adding a via hole does not reach the inflection point;When the primary and secondary coil turn numbers are different, the bridge and the lead-out port after the bridge should not reach the inflection point.

[0022] A computer program product comprises computer programs / instructions, which, when executed by a processor, implement the steps of the automatic on-chip transformer drawing method.

[0023] Advantages: Compared with the prior art, the automatic on-chip transformer drawing method provided by the application has the following advantages:

[0024] (1) The application can realize automatic drawing of on-chip transformers and output a layout only by using structure parameters of the transformer, greatly improving the work efficiency of radio frequency circuit designers;

[0025] (2) The application supports transformer drawing of three structures, i.e., arbitrary polygon interleaved mutual winding, symmetric mutual winding and symmetric lamination, and various turn ratios, can increase tap structure, is versatile, and can cover common radio frequency application scenarios;

[0026] (3) The application can screen the drawing structure combined with geometric prior knowledge, so that the success rate of automatic drawing of on-chip transformers reaches 100%, and promotes the automation and intelligent design of radio frequency circuit design. BRIEF DESCRIPTION OF DRAWINGS

[0027] Fig. 1 is a schematic diagram of unit direction vectors and normal unit direction vectors of the inner circle quadrilateral;

[0028] Fig. 2 is a schematic diagram of the process of drawing metal according to coordinates of the interleaved mutual winding quadrilateral transformer;

[0029] Fig. 3 is a schematic diagram of comparison before and after port coordinate adjustment of the interleaved mutual winding quadrilateral transformer;

[0030] Fig. 4 is an example diagram of automatic drawing structure of the interleaved mutual winding quadrilateral transformer;

[0031] Fig. 5 is a schematic diagram of the symmetric mutual winding quadrilateral transformer and translation vector;

[0032] Fig. 6 is a schematic diagram of two side translations of the symmetric mutual winding quadrilateral transformer;

[0033] Fig. 7 is a schematic diagram of metal labels of the symmetric mutual winding quadrilateral transformer;

[0034] Fig. 8 is a schematic diagram of cross-wiring of the symmetric mutual winding quadrilateral transformer;

[0035] Fig. 9 is a schematic diagram of midpoint translation bridging of the symmetric mutual winding structure;

[0036] Fig. 10 is an example diagram of automatic drawing structure of the symmetric mutual winding quadrilateral transformer;

[0037] Fig. 11 is an example diagram of automatic drawing structure of various on-chip transformers. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the embodiments of the application clearer, the technical scheme in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application.

[0039] The automatic drawing method of the on-chip transformer disclosed in the embodiments of the application mainly includes the following steps: first, obtaining the structure parameters of the on-chip transformer, including the shape of the inner circle polygon, the inner diameter, the line width, the line spacing and the number of turns; then determining the positions of the vertices of the inner circle polygon and the unit direction vectors and the unit normal vectors of each edge of the inner circle polygon according to the shape of the inner circle polygon and the inner diameter; then obtaining the vertices of the primary and secondary coils by translating the unit direction vectors of the edges along the unit normal vectors to intersect, wherein the translation distance is determined according to the line width and the line spacing of the transformer; finally, adjusting the input and output port coordinates and arranging the wires.

[0040] The method of the embodiment of the application can be applied to various on-chip transformer structures, including interleaved mutual-winding transformers, symmetric mutual-winding transformers and symmetric stacked transformers, can realize transformer drawing of any polygon and various turn ratios, can increase tap structures and can cover common radio frequency circuit application scenarios. The primary coil and the secondary coil of the interleaved mutual-winding transformer are interleaved and wound in the same metal layer and are centrally symmetrically distributed; the input port of the two-stage coil is connected with the outermost metal, and the output port is connected with the innermost metal through a via hole; the line width and the line spacing of the primary coil and the secondary coil are the same.

[0041] The primary coil and the secondary coil of the interleaved mutual-winding transformer are drawn respectively, and then the wiring arrangement is performed. First, the shape and size of the innermost polygon are determined, then the vertex coordinates of each metal segment are obtained by translating and intersecting each side of the polygon according to the line width and the line spacing of the transformer, and finally the input and output ports are adjusted.

[0042] The automatic drawing method of the interleaved mutual-winding transformer will be described in detail below, and the specific drawing includes the following steps:

[0043] Step 101: determining the positions of the vertices of the innermost polygon. For convenience of representation, polar coordinates are adopted, and a regular n-polygon is taken as an example, with an inner diameter of D in The left lower corner of the regular polygon is taken as the first vertex, and the count is rotated in the counterclockwise direction, so that the polar radii of the vertices are:

[0044]

[0045] The angular coordinates of the points are:

[0046]

[0047] Thus, the vertex polar coordinates (R, θ i ) can be obtained. Then, the vertex polar coordinates are converted into rectangular coordinates, and the vertex coordinates a1=[x1,y1], a2=[x2,y2], …, a n =[x n ,y n ] of the innermost polygon can be obtained.

[0048] Step 102: calculating the straight line equations of the sides of the innermost polygon. The straight line equations of the sides of the innermost polygon are obtained by connecting the first vertex in the counterclockwise order:

[0049] k1x+k2y+k3=0

[0050] wherein k1=y i+1 -y i , k2=x i -x i+1 , and k3=x i+1 y i -x iy i+1 i = 1, 2,..., n. Similarly, each edge unit direction vector e i :

[0051]

[0052] Rotate e u clockwise by 90 degrees to get each edge unit normal vector t u :

[0053] t i = e i ·T

[0054] where, is a 90-degree rotation matrix.

[0055] Step 103: Translate the above straight lines, and intersect each other to get the coordinates of the primary and secondary coil vertices. Take each edge of the inner polygon as the base, since each edge of the coil is parallel to each edge of the inner polygon, the remaining edges of the primary and secondary coils can be obtained by translating each edge unit direction vector along the unit normal vector and intersecting it. The translation distance is related to the line width and line spacing of the transformer. Assuming the translation vector of the straight line is p = [m, n], p is in the direction of the unit normal vector, then the equation of the translated straight line is

[0056] k1(x-m) + k2(y-n) + k3 = 0

[0057] After obtaining the translated edges, the outer vertices can be obtained by intersecting the new straight lines.

[0058] Step 104: Adjust the input and output port coordinates, and connect the transformer metal segments according to the vertex coordinates. The transformer has inner and outer coils, and only one layer of metal cannot complete all the wiring. The innermost port needs to be connected to the outside by the lower metal lead to facilitate subsequent connection and use. At the same time, considering the metal loss and parasitic effect caused by too small metal conductor distribution spacing, the innermost vertex position 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 parallelly wound in the same metal layer and axially symmetrically distributed; the input and output ports of the primary coil are directly connected to the outermost metal, and the input and output ports of the secondary coil are connected to the outermost metal through a through hole; 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 respectively, the transformer sketch is drawn according to the innermost polygon, the coils are divided into left and right symmetric parts by the median line, the metal segment connection order is determined, and finally the left and right symmetric metal parts are bridged in turn to draw the cross-wiring part.

[0060] The automatic drawing method of the symmetrical interwinding transformer is described in detail below, and the specific drawing includes the following steps:

[0061] Step 201: Refer to steps 101 to 103, draw the transformer sketch according to the innermost polygon. First, draw the innermost polygon from the inner diameter D un Calculate the vertices of the innermost polygon, determine the line width W, line spacing S, and the number of turns N p / N s and other structural parameters. Then calculate the unit direction vector e and the unit normal vector t of each edge of the innermost polygon according to the formula, and then perform translation intersection to obtain the primary and secondary coil vertices, i.e. multiple concentric polygons as the sketch of the symmetrical transformer.

[0062] Step 202: Divide the coil into two symmetrical parts by the median line. Calculate the midpoint coordinates of the upper and lower edges from the innermost polygon vertex coordinates to obtain the median line equations of the upper and lower edges.

[0063] Step 203: Determine the metal connection sequence. Divide the coil into two parts, and label each metal from outside to inside and distinguish the head and tail. The left coil has the head above and the tail below, and the right coil has the head below and the tail above. When drawing the cross-wiring, always go from the head to the tail, i.e. the head of the previous metal is connected to the tail of the next metal, and the connection of which two metals is determined according to a certain sequence. First, set the wiring flag flag, flag = 1 indicates inward wiring, flag = -1 indicates outward wiring, and the initial flag is 1. Start from the metal segment with label 1, and then discuss the case. If the current metal label is not equal to 2, continue to judge the flag. If flag = 1 and the current 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 = -1; if flag = 1 and the current is not 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; if flag = -1, connect the head of the current metal segment to the tail of the other half of the outer circle, update the label. For the common number of turns of the coil, the connection sequence between metals can also be stored in advance according to the numbering rule.

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

[0065] The automatic drawing method of symmetric stacked transformer is similar to symmetric interleaved transformer, the primary coil and the secondary coil are parallel wound in multiple layers of metal, and are distributed in axial symmetry; the input and output ports of the primary coil are directly connected to the outermost metal, and the input and output ports of the secondary coil are connected to the outermost metal through a through hole; the line width and line spacing of the primary coil and the secondary coil are the same. For some common coil turn ratio, the metal layer, the connection sequence between the metal segments in the layer and the metal segments between the layers can be pre-set, and during the specific drawing, the cross-wiring and the interlayer through-hole design are performed according to the pre-set rules.

[0066] In some embodiments, the on-chip transformer automatic drawing method further comprises tap drawing, adding the metal segment number and the 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 interleaved winding transformer, the tap can be allocated to the whole region, and in the symmetric interleaved transformer and the symmetric stacked transformer, the tap can be allocated to the region except the cross-wiring part. The relative position is evenly distributed in the counterclockwise direction from one port of the coil to the other port, and gradually increases along the metal direction, and the middle position is 0.5, that is, the center tap is a common tap position selection.

[0067] In the process of automatic modeling and drawing of the transformer, the area limitation is particularly important, and the chip size and cost are closely related. Especially for passive devices such as on-chip inductors and on-chip transformers, in addition to the area of the device itself, attention should also be paid to the interference of the inductor and the transformer on other devices. The common practice is to pre-leave space for other modules or add additional isolation modules, so the actual occupied area will be larger, therefore, 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 too small inner diameter will lead to modeling error of the inner coil (especially for octagonal transformer), and then affect the overall modeling effect.

[0068] In some embodiments, the geometric prior knowledge is combined to pre-screen the drawing structure, which can effectively improve the modeling success rate, and the automatic modeling success rate can reach 100%. Let the line width of the transformer be W, the line spacing be S, the inner diameter be D in , the cross-wiring width be W Bridge , the port width be W Port , and the upper and lower layer through-hole width be W Via . To ensure correct modeling, the inside of the metal segment should not reach the inflection point after the center line is shifted to the left and right sides to form a bridge, and the outside of the metal segment should not reach the inflection point after the through hole is added. When the primary and secondary coil turns are different, the bridge and the output port should also be ensured not to reach the inflection point, 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 primary and secondary coil turns.

[0069] The structure parameters of symmetric same-layer n:n quadrilateral transformer need to meet:

[0070]

[0071] The symmetric same-layer n:n octagonal transformer structure parameters need to meet:

[0072]

[0073] The symmetric same-layer 1:2, 2:3, 2:1, 3:2 quadrilateral transformer structure parameters need to meet:

[0074]

[0075] The symmetric same-layer 1:2, 2:3, 2:1, 3:2 octagonal transformer structure parameters need to meet:

[0076]

[0077] The symmetric stacked 1:1 quadrilateral transformer structure parameters need to meet:

[0078]

[0079] The symmetric stacked 1:1 octagonal transformer structure parameters need to meet:

[0080]

[0081] The symmetric stacked 2:2 quadrilateral transformer structure parameters need to meet:

[0082]

[0083] The symmetric stacked 2:2 octagonal transformer structure parameters need to meet:

[0084]

[0085] The symmetric stacked 1:2, 2:1 quadrilateral transformer structure parameters need to meet:

[0086]

[0087] The symmetric stacked 1:2, 2:1 octagonal transformer structure parameters need to meet:

[0088]

[0089] Wherein, △ is the interval between the port and the via when the cross-over line is required to meet the chip design rules, which can be freely adjusted.

[0090] The automatic drawing method of on-chip transformer will be exemplarily illustrated below in combination with two design examples of staggered mutual winding transformer and symmetric mutual winding transformer.

[0091] Example 1: Automatic drawing of interleaved mutual winding quadrilateral transformer

[0092] Step 301: Determine the position of each vertex of the inner circle. For convenience of representation, polar coordinates are used, with the left lower corner of the quadrilateral as the first vertex, rotating counterclockwise by a count of 1, and then converting it 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 straight line equation of 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] Unit direction vector and normal unit direction vector of each side:

[0099]

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

[0101] The inner circle vector drawing is shown in Figure 1.

[0102] Step 303: Translate the above straight lines to intersect each other to obtain the primary and secondary winding vertex coordinates 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 circle vertex of the primary winding. Points A and B are the first and second vertices a in1 and b in1 of the metal inner side, and the straight line l11 By l AB It is obtained by translating along vector p2, requiring only a distance of one line width, to obtain line l. DA and line l 11 The intersection yields the first vertex a on the outer side of the metal. out1 Line l BC The line l is obtained by translating along the direction of the normal vector by a distance equal to the line width. 21 , and l 11 Intersecting at the second outer vertex b out1 Line l CD The line l is obtained by translating along vector p1. 31 This means shifting the line by a distance equal to one line width plus one line spacing, leaving space in between for the secondary coils. The straight line l... BC and line l 31 The intersection yields the third vertex c on the inner side of the metal. in1 Line l 31 Continuing to translate along the p1 direction by a distance equal to the line width, we obtain the straight line l. 32 , and l 21 Intersects at the third vertex c on the outer side out1 Line l DA The line l is obtained by translating outward along the normal vector by a distance equal to the line width plus the line spacing. 41 , l 41 and line l 31 The fourth vertex d intersects on the inside in1 Then, continue to translate by a distance equal to the line width to obtain the straight line l. 42 Line l 42 and line l 32 The intersection yields the fourth vertex d on the outer side. out1 A coil of metal requires four segments, five vertices on both the inner and outer sides, to form a fifth vertex. To obtain the fifth vertex on both the inner and outer sides, a second coil of the first segment of metal is needed. [The following sentence appears unrelated and likely refers to a different concept:] ...the straight line l... 11 The line l is obtained by translating along vector p3. 12 This means shifting the line by a distance equal to one line width plus twice the line spacing, reserving space for the secondary coil, and using a straight line l. 12 and l 41 The intersection yields the first vertex a of the second inner ring. in l 12 Continue translating outwards by a distance equal to the line width to obtain the straight line l. 13 , intersecting line l 42 At the first vertex a of the second outer ring out2 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 line and the coordinates of each vertex of the primary coil can be obtained.

[0109] After obtaining the vertex coordinates, the metal can be generated using the SKILL script to call VIRTUOSO, as shown in Figure 2(b). A similar method can automatically draw the secondary coil metal, as shown in Figure 3(a). However, in this case, the first port on the inner and outer sides of the primary and secondary coils being connected to adjacent metals will cause short circuits and other losses; therefore, its coordinates are adjusted to those in Figure 3(b). The specific ending position can be determined based on the number of turns. It is worth noting that the end port of the coil should also avoid being connected to other metals.

[0110] The final drawing of the interleaved quadrilateral transformer is shown in Figure 4.

[0111] Example 2: Automatic drawing of symmetrically wound quadrilateral transformers

[0112] Step 401: Draw the prototype of the transformer based on the innermost polygon. First, draw the inner diameter D... 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, unit direction vectors, and unit normal vectors of each side. The remaining lines are obtained through translation, as shown in Figure 5. There are two types of translation vectors: one is between the inner and outer sides of the same metal piece, requiring a translation distance equal to one line width (p1 in Figure 5); the second case requires traversing the metal of the secondary coil, requiring a translation distance equal to twice the line width plus the line spacing (p2 in Figure 5). The coordinates of the vertices of the metal are obtained by the intersection of the lines. Thus, 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 top and bottom sides, and divide the coil into left and right parts. Figure 6 shows the symmetrical primary and secondary coils when they are divided but do not cross each other. Subsequently, the metal on both sides will be translated from the perpendicular bisector to both sides.

[0116] Step 403: Determine the metal connection sequence. Number the left and right sides of the metal respectively, and Fig. 7 shows the numbering of the primary coil metal, the primary and secondary coil are numbered separately, and the cross-bridge is crossed. When the number of turns is 2:2, the metal connection sequence is 1→4→3→2.

[0117] Step 404: The left and right symmetrical two-part metal "bridge" is drawn, and the cross-wiring part is drawn. The basic idea is to translate the end points from the midpoint of each side to the left and right sides, reserve space for the bridge, form new end points, 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 end points, and then the coordinates after translation are calculated according to the unit direction vector of each side, so that automatic drawing can be completed. It needs to be noted that the metal main part is in the same metal layer, and the wiring part needs to be transitioned 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 needed, the middle layer is used for metal main body distribution, and the upper and lower layers are used for wiring.

[0118] As shown in Fig. 8, the cross-wiring part is taken as an example, M is the midpoint of the upper side, M L and M R are the wiring points needed to be solved on the left and right sides. Two translation vectors p3, p4 can be obtained from the unit direction vector of the CD side. After translation, the wiring should meet the chip design rules. The isosceles triangle shown in the figure can ensure 45-degree wiring, and considering that the adjacent metal belongs to two coils, the length of the right angle side is twice the line width plus twice the line spacing, as shown in Fig. 9, so

[0119] p3 = -2 × (W + S)e CD

[0120] p4 = 2 × (W + S)e CD

[0121] The coordinates of M L and M R points can be calculated, and the coordinates of other cross-wiring left and right side vertices are obtained in the same way. After the coordinates are calculated, the layout is generated by calling VIRTUOSO, as shown in Fig. 10. The input and output port positions of the primary and secondary coils are adjusted to prevent short circuit and facilitate cascading. The secondary coil port is led out through the lower layer lead. The metal is connected in order according to the numbering, and the metal layer distribution is performed according to the distribution of the cross-wiring, so as to avoid the overlap of the "bridge".

[0122] Fig. 11 shows various on-chip transformer structure diagrams automatically drawn based on the method of the present application.

[0123] The embodiment of the present application also discloses a computer program product comprising computer programs / instructions which, when executed by a processor, implement the steps of the on-chip transformer automatic drawing method. The program / instruction code for implementing the method of the present application can be written in any combination of one or more programming languages. These program / instruction codes can be provided to the processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus, so that the program / instruction codes, when executed by the processor or controller, cause the steps of the method of the present application to be implemented. The program / instruction codes can be executed entirely on a machine, partially on a machine, partially on a machine as a separate software package, and partially on a remote machine, or entirely on a remote machine or server.

[0124] The details of the present application not described are known to those skilled in the art.

[0125] To sum up, only the specific implementation of the present application, but the scope of protection of the present application is not limited to this, any skilled in the art of the present application disclosed in the technical range, can easily think of changes or replacement, should be covered in the scope of protection of the present application. Therefore, the scope of protection of the present application should be subject to the scope of protection of the claims.

Claims

1. An on-chip transformer automatic layout method, characterized by, The method comprises the following steps: Obtaining the structure parameters of the on-chip transformer, including the inner circle polygon shape, inner diameter, line width, line spacing and number of turns; Determining the positions of each vertex of the inner circle according to the inner circle polygon shape and the inner diameter, and the unit direction vector and the unit normal vector of each edge of the inner circle polygon; Obtaining each vertex of the primary and secondary coils by translating the unit direction vector of each edge along the unit normal vector to intersect, and the translation distance is determined according to the transformer line width and line spacing; Adjusting the coordinates of the input and output ports and arranging the lines.

2. The method of claim 1, wherein, The process of determining the position of each vertex of the inner circle based on the number of sides and the inner diameter includes: determining the polar diameter of each vertex using polar coordinates. and angular coordinates Obtain the polar coordinates of the vertex (R, θ) i ), then convert to rectangular coordinates; where D in Let n be the inner diameter, and n be the number of sides of the regular polygon. The straight line equation of the forming edge of the adjacent vertex is calculated by using the rectangular coordinates, and then the unit direction vector and the unit normal vector of each edge are obtained.

3. The method of claim 1, wherein, The on-chip transformer is a staggered mutual winding transformer, the primary coil and the secondary coil are staggered and wound in the same metal layer, and are centrally symmetrically distributed; the input port of the two-stage coil is connected with the outermost metal, and the output port is connected with the innermost metal through a through hole; the line width and the line spacing of the primary coil and the secondary coil are the same.

4. The method of claim 1, wherein, The on-chip transformer is a symmetric mutual winding transformer, the primary coil and the secondary coil are parallel wound in the same metal layer, and are axially symmetrically distributed; the input and output ports of the primary coil are directly connected with the outermost metal, and the input and output ports of the secondary coil are connected with the outermost metal through a through hole; the line width and the line spacing of the primary coil and the secondary coil are the same.

5. The method of claim 4, wherein, The primary and secondary coils of the symmetric mutual winding transformer are drawn respectively, the transformer prototype is drawn according to the innermost circle polygon, the coil is divided into two symmetrically left and right parts by the median line, the metal segment connection sequence is determined, and finally the left and right symmetric two parts of metal are bridged in sequence to draw the cross line part.

6. The method of claim 4, wherein, The determination of the metal segment connection sequence comprises: The coil is divided into two left and right parts, each metal segment is sequentially numbered from outside to inside and is distinguished as a head and a tail; it is recorded that the upper part of the left coil is the head and the lower part is the tail, and the lower part of the right coil is the head and the upper part is the tail; when drawing the cross line, it is always from the head to the tail; A line marking bit flag is set, flag is 1, indicating that the line is inward, flag is -1, indicating that the line is outward, and the initial flag is 1; starting from the metal segment with the number 1, the case is discussed, if the current metal number is not equal to 2, the flag is continuously judged, if the flag is 1 and the current is in the innermost circle, the head of the current metal segment is connected with the tail of the other half of the circle, the number is updated, and the flag is updated to -1; if the flag is 1 and the current is not in the innermost circle, the head of the current metal segment is connected with the tail of the other half of the inner circle, and the number is updated; if the flag is -1, the head of the current metal segment is connected with the tail of the other half of the outer circle, and the number is updated.

7. The method of claim 1, wherein, The on-chip transformer is a symmetric stacked transformer, the primary coil and the secondary coil are parallel wound in multiple metal layers, and are axially symmetrically distributed; the input and output ports of the primary coil are directly connected with the outermost metal, and the input and output ports of the secondary coil are connected with the outermost metal through a through hole; the line width and the line spacing of the primary coil and the secondary coil are the same.

8. The method of claim 1, wherein, Also include transformer tap drawing, first determine the tap metal segment number, and then determine the metal relative position parameters; In interleaved mutual winding transformer, the tap can be assigned to the full area, in symmetric mutual winding transformer and symmetric laminated transformer, the tap can be assigned to the area except the cross wiring part.

9. The method of claim 1, wherein, The method combines geometric prior knowledge to pre-screen the drawing structure, and determines specific constraints according to the transformer structure form and the primary and secondary coil turns to ensure correct modeling, including: the inside of the metal segment does not reach the inflection point after the middle line is translated to the left and right sides and bridged; The outside of the metal segment does not reach the inflection point after adding a through hole; When the primary and secondary coil turns are different, the bridge and the outlet port should not reach the inflection point after being ensured.

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

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