A 65nm CMOS 0.1–2.1GHz linear-in-dB VGA with active-inductor bandwidth extension for the Square Kilometer Array

In this paper, a 65nm CMOS broadband linear-in-dB Variable-Gain Amplifier (VGA) circuit for use in the Square Kilometer Array (SKA) is proposed. Active inductor loads are used to extend the 3dB bandwidth of the VGA over previous designs. Measurements show that the VGA is broadband, has a 3dB upper band edge of 2.1GHz, and easily covers the mid-band SKA range from 0.7GHz to 1.4GHz. The VGA has a maximum controllable gain range from −12.5dB to +22.4dB and a linear-in-dB range with 1dB error from −12.5dB to +16dB. Measured input P1dB is approximately −22dBm. The power consumption of the VGA is 1.1mW with another 5.1mW consumed by an input-match circuit and 11mW consumed by an output buffer circuit.