A 0.4 to 10.8GHz, +20dBm OIP3 Broadband Switchable Differential to Single-Ended Active Balun in 130-nm BiCMOS Technology

In this paper, a 0.4-10.8 GHz active balun in 130nm SiGe BiCMOS technology is presented. The balun realizes differential to single-ended (D2S) conversion using two paths, one with common collector (CC) structure and the other with common emitter (CE) structure. The CE path, together with the bias circuit, constructs a proportional current mirror that makes the balun switchable. In order to make the two input impedances as equal as possible, the emitter follower (EF) structure is adopted as the buffer. The bond wire inductance and package parasitic parameters are considered to be a part of the output matching network (OMN) to enhance the bandwidth (BW). Designed in 130-nm BiCMOS process, this work achieves 3-dB BW of 0.4-10.8 GHz, an output compression point (OP1dB) of 8.9dBm, third-order intercept point (OIP3) of 20.7dBm at 1GHz, respectively. The maximum phase error of the active balun is 4 degrees and the maximum amplitude error is 1.7 dB over 0.4-10.8 GHz frequency range. The chip area is 0.105 mm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> with a static power consumption of 66mW.