An integrated circuit based transformer (200; 250; 400; 500; 600; 1000), comprising: a primary winding (202; 252; 402; 502; 1002) located in a winding layer, the primary winding (202; 252; 402; 502; 1002) having two primary terminals (205, 206; 255, 256; 410, 411; 510, 511; 1011, 1014) at a first side of the transformer (200; 250; 400; 500; 600; 1000); a secondary winding (203; 253; 403; 503; 1003) located in a winding layer, the secondary winding (203; 253; 403; 503; 1003) having two secondary terminals (208, 209; 258, 259; 413, 414; 513, 514; 1012, 1013) at a second side of the transformer (200; 250; 400; 500; 600; 1000), the first and second sides located at different sides of the transformer (200; 250; 400; 500; 600; 1000); and a reference bar (204; 254; 404; 504; 584; 86; 96; 1004; 1104) located in a reference bar layer, the reference bar (204; 254; 404; 504; 584; 86; 96; 1004; 1104) having a primary reference bar terminal (207; 257; 412; 512) at the first side of the transformer (200; 250; 400; 500; 600; 1000), and having a secondary reference bar terminal (210; 260; 415; 515) at the second side of the transformer (200; 250; 400; 500; 600; 1000), wherein the reference bar (204; 254; 404; 504; 584; 86; 96; 1004; 1104) is configured to provide a direct electrical connection between the first reference bar terminal (207; 257; 412; 512) and the second reference bar terminal (210; 260; 415; 515) characterised in that the primary winding (202; 252; 402; 502; 1002), the secondary winding (203; 253; 403; 503; 1003) and the reference bar (204; 254; 404; 504; 584; 86; 96; 1004; 1104) are mirror symmetric about an axis (406; 506; 1006) oriented along the longitudinal axis of the reference bar (204; 254; 404; 504; 584; 86; 96; 1004; 1104). a primary winding (202; 252; 402; 502; 1002) located in a winding layer, the primary winding (202; 252; 402; 502; 1002) having two primary terminals (205, 206; 255, 256; 410, 411; 510, 511; 1011, 1014) at a first side of the transformer (200; 250; 400; 500; 600; 1000); a secondary winding (203; 253; 403; 503; 1003) located in a winding layer, the secondary winding (203; 253; 403; 503; 1003) having two secondary terminals (208, 209; 258, 259; 413, 414; 513, 514; 1012, 1013) at a second side of the transformer (200; 250; 400; 500; 600; 1000), the first and second sides located at different sides of the transformer (200; 250; 400; 500; 600; 1000); and a reference bar (204; 254; 404; 504; 584; 86; 96; 1004; 1104) located in a reference bar layer, the reference bar (204; 254; 404; 504; 584; 86; 96; 1004; 1104) having a primary reference bar terminal (207; 257; 412; 512) at the first side of the transformer (200; 250; 400; 500; 600; 1000), and having a secondary reference bar terminal (210; 260; 415; 515) at the second side of the transformer (200; 250; 400; 500; 600; 1000), wherein the reference bar (204; 254; 404; 504; 584; 86; 96; 1004; 1104) is configured to provide a direct electrical connection between the first reference bar terminal (207; 257; 412; 512) and the second reference bar terminal (210; 260; 415; 515) characterised in that the primary winding (202; 252; 402; 502; 1002), the secondary winding (203; 253; 403; 503; 1003) and the reference bar (204; 254; 404; 504; 584; 86; 96; 1004; 1104) are mirror symmetric about an axis (406; 506; 1006) oriented along the longitudinal axis of the reference bar (204; 254; 404; 504; 584; 86; 96; 1004; 1104).