Contents I. Introduction
Since both phase and gain controls are required in phased-array antenna systems, implementations of their functional blocks are widely studied [1]–[4]. Conventional phase and gain control circuits are generally implemented with two functional blocks, which requires a large chip area and high power consumption. Therefore, there have been many studies to distribute the gain-control function to other functional blocks without a dedicated gain-control block to reduce chip size and power consumption. Gain control in a low-noise amplifier (LNA) [5], [6] and a power amplifier (PA) [7] are introduced, but the gain controls in an LNA and a PA stage may deteriorate the overall system noise figure (NF) and the linearity, respectively. Active phase shifters are of great interest because they have smaller chip areas and less insertion losses with high bit resolutions compared to passive-type phase shifters [4], [8]–[11]. Recently, several studies have been done to add gain control functions to active phase shifters, which are an attenuator-based variable-gain phase shifter (VGPS) [12] and a polar vector modulator-type phase shifter [13], [14]. From a system perspective, phase and gain controls should be orthogonal to control beams precisely and to suppress their side lobes [1]. However, previously reported VGPSs have high phase error during gain control, which requires additional calibration processes. We previously reported a dual-vector (DV) VGPS [15], which has an orthogonal phase and gain control function. However, it has a narrow gain-control dynamic range (7 dB) and requires complicated three differential DACs.
