A Dual-Band Switchable MMIC Star Mixer

In this letter, a dual-band switchable MMIC star mixer is proposed. The MMIC is fabricated in a 0.1-
$\mu \text{m}$
commercial GaAs pHEMT process with a chip size of 1.1 mm
$\times1.3$
mm. The operating frequency band can be switched between 43–63 GHz and 55–85 GHz by changing the effective length of Marchand balun. Band selection is controlled by the bias voltage of pHEMT switches. The measurements show the conversion loss of 7–10 dB over the lower band and 10.5–13 dB over the higher band. The RF-to-local oscillator (LO) isolation has also been measured to be over 35 dBc. The modified star mixer can be used for dual-band millimeter-wave wireless communication or radar application.