A 8.5 to 11.6 GHz digitally controlled variable gain amplifier with 15‐dB gain range and 1‐dB step

Abstract

A X-band variable gain amplifier (VGA) with low phase variation and high control resolution is presented in 180-nm CMOS. The linear gain VGA and current-type digital-toanalog converter (DAC) are implemented to improve the accuracy of gain control and the robustness against process, supply voltage, and temperature variations (PVT). The measured peak gain and 3-dB bandwidth are 8 dB and 8.5 to 11.6 GHz, respectively. The gain range is 15 dB with a gain step of 1 dB. With a supply voltage varying from 1.6 to 2.0 V, the root-mean-square (RMS) gain and phase errors in 3-dB bandwidth are <0.62 dB and <1.5 , respectively. With supply of 1.8 V, the measured root-meansquare (RMS) gain and phase errors across −25 to 110 C are <0.65 dB and <1.7 , respectively. Comparing the measurement results of five chips, the variation of RMS gain error is <0.24 dB, and the RMS phase errors are almost the same. The measurement results demonstrate the proposed VGA is very suitable for phased arrays in X-band.

X‐Band 130‐nm CMOS transceiver front‐end with a broadband attenuator design for phased‐array systems

“…For phased-array transceiver, amplitude control can be achieved by passive attenuator [6][7][8][9] or active variable gain amplifier (VGA). [10][11][12][13][14][15][16][17] Attenuators usually have high linearity, low power consumption, and simple structure. However, due to the low isolation, the amplitude-phase performance is easily affected by the front and rear loads.…”

“…As an urgent demand for communication rate and range resolution of the systems, transceivers usually require greater bandwidth. For phased‐array transceiver, amplitude control can be achieved by passive attenuator 6–9 or active variable gain amplifier (VGA) 10–17 . Attenuators usually have high linearity, low power consumption, and simple structure.…”

A V‐band digitally controlled low noise variable gain amplifier with 3.5° phase variation in 28‐nm bulk CMOS

“…To minimize the phase variation during gain tuning, several VGAs using different techniques have been proposed. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] A current steering topology is widely used to achieve gain tuning. 2,3,8,13,14 The common source (CS) transistor in the cascode amplifier of the current steering topology has a constant DC current, so the input impedance and the transconductance gm are maintained during gain tuning.…”

“…At the same time, the noise figure (NF) is quite high. Thus, it is preferable to use a digital control module to achieve gain tuning 7 . In addition, the phase inversion network, 4 differential matching technique, 6 phase compensation capacitor, 9 capacitor control technique, 10 local feedback technology, 11 and capacitor elimination technique 12 are proposed to reduce the phase variation of the VGA.…”

“…To minimize the phase variation during gain tuning, several VGAs using different techniques have been proposed 1–14 . A current steering topology is widely used to achieve gain tuning 2,3,8,13,14 .…”