A compact capacitor compensated wideband balun in CMOS technology

A novel balun manufactured in standard CMOS 0.18 mum is proposed that demonstrates a very large wideband operation. This device achieves this through the use of an external compensating capacitor to counter the effects of parasitic capacitances. An input stage common gate amplifier is then used to improve the return loss and provide additional gain. The fabricated active balun using the proposed circuit shows that the device performs with a 7.5 GHz bandwidth centered at 3.5 GHz. In addition an excellent 15 dB return loss, -5.8 dBm compression point and 12 mW power consumption are also reported.