A 12 GHz 22 dB-Gain-Control SiGe Bipolar VGA With 2° Phase-Shift Variation

Abstract

A 12 GHz VGA showing a gain variation range from $-9\;\text{dB}$ to $13\;\text{dB}$ with a linear-in-dB gain control feature is presented in this work. As the gain is changed, the phase shift over the entire 10–14.4 GHz bandwidth varies as little as $\leq$ 2° due to a compensation circuitry that reduces the input-output phase shift sensitivity to gain variations in a robust manner with respect to temperature changes. Such a reduced phase shift variation is particularly useful to simplify the signal phase/amplitude control for the various paths of a phased array system, and allows to implement ultra-low sidelobe phased arrays. The VGA prototypes, implemented in a SiGe bipolar technology, show a noise figure of 5.1 dB, an IIP3 of $- 3\;{\rm dBm}$ , a ${P_{1{\rm dB}}}$ of $- 17\; \text{dBm}$ , and a power consumption of 83 mW.