A broadband radio frequency, microwave, or millimeter mixer system comprising: a balun without a magnetic core that has: an unbalanced port; a balanced port (RF-, RF+); a first and a second inductor; wherein a first end of the first inductor is coupled to the unbalanced port and a second end of the first inductor is connected to a first side of the balanced port (RF+); wherein a first end of the second inductor is coupled to ground and a second end of the second inductor is coupled to a second side of the balanced port (RF-); and wherein the first and the second inductor are tightly magnetically coupled to one another by routing the first inductor from its first end to its second end side-by-side to the second inductor from its first end to its second end; and a third inductor which is coupled in series with the first inductor and to ground and which is not magnetically coupled to the first or the second inductors, wherein a first end of the third inductor is coupled to ground and a second end of the third inductor is connected to the second side of the balanced port (RF-); and a mixer connected to the balanced port of the balun, wherein the balun, including its three inductors, and the mixer are all integrated onto a single substrate that forms an integrated circuit, and wherein, when an unbalanced signal is applied to the unbalanced port, the unbalanced signal is voltage divided between the impedances of the first and third inductors. a balun without a magnetic core that has: an unbalanced port; a balanced port (RF-, RF+); a first and a second inductor; wherein a first end of the first inductor is coupled to the unbalanced port and a second end of the first inductor is connected to a first side of the balanced port (RF+); wherein a first end of the second inductor is coupled to ground and a second end of the second inductor is coupled to a second side of the balanced port (RF-); and wherein the first and the second inductor are tightly magnetically coupled to one another by routing the first inductor from its first end to its second end side-by-side to the second inductor from its first end to its second end; and a third inductor which is coupled in series with the first inductor and to ground and which is not magnetically coupled to the first or the second inductors, wherein a first end of the third inductor is coupled to ground and a second end of the third inductor is connected to the second side of the balanced port (RF-); and an unbalanced port; a balanced port (RF-, RF+); a first and a second inductor; wherein a first end of the first inductor is coupled to the unbalanced port and a second end of the first inductor is connected to a first side of the balanced port (RF+); wherein a first end of the second inductor is coupled to ground and a second end of the second inductor is coupled to a second side of the balanced port (RF-); and wherein the first and the second inductor are tightly magnetically coupled to one another by routing the first inductor from its first end to its second end side-by-side to the second inductor from its first end to its second end; and a third inductor which is coupled in series with the first inductor and to ground and which is not magnetically coupled to the first or the second inductors, wherein a first end of the third inductor is coupled to ground and a second end of the third inductor is connected to the second side of the balanced port (RF-); and a mixer connected to the balanced port of the balun, wherein the balun, including its three inductors, and the mixer are all integrated onto a single substrate that forms an integrated circuit, and wherein, when an unbalanced signal is applied to the unbalanced port, the unbalanced signal is voltage divided between the impedances of the first and third inductors.