Wideband Variable-Gain Amplifiers Based on a Pseudo-Current-Steering Gain-Tuning Technique

Abstract

This paper reports two variable-gain amplifiers (VGAs) featuring a new pseudo-currentsteering gain-tuning technique. In the first VGA (VGA-I), a single-voltage-controlled dual-branch current mirror is developed as a standalone gain control block. In the second VGA (VGA-II), two NMOS transistors, which are biased by a tunable voltage, are integrated into a conventional common-source amplifier to steer away from a part of the total current. Meanwhile, the theoretical analysis is developed to reveal the mechanism of different gain tuning. Fabricated in a 40-nm CMOS process, VGA-I (VGA-II) occupies a tiny area of 0.03 mm 2 (0.024 mm 2) and consumes 22 mW (20 mW). Measured over a gain range of > 64 dB, the-3-dB bandwidth of VGA-I (VGA-II) is 9 GHz (6.6 GHz). For the time-domain tests, VGA-I (VGA-II) exhibits a jitter of 40 ps (30 ps), under a 2 7-1 PRBS input at 12 Gb/s. Their power efficiencies (1.83 and 1.67 pJ/bit) compare favorably with state-of-the-art. INDEX TERMS CMOS, high-speed transceiver, variable-gain amplifier (VGA), negative capacitance (NC), peak-to-peak jitter, data-dependent jitter (DDJ), pseudo-current steering, wide-tuning gain control, dual-branch current mirror, active inductor.

A 90‐ to 115‐GHz superheterodyne receiver front‐end for W‐band imaging system in 28‐nm complementary metal‐oxide‐semiconductor

“…Finally, the differential I/Q baseband signals successfully emerge for signal processing in poststage circuits, such as the IF2 filter 24,25 and variable gain-controlled amplifier. [26][27][28] The broadband LNA and the mixer are the key subblocks responsible for signal amplification and frequency conversion, which locate at the front-end of the RX and have a great impact on the RF performance of the whole system. Therefore, the technical requirements for these parts are also the highest, which will be discussed in detail in the following sections.…”

“…Additionally, in the LO signal chain of the second down‐conversion, a CML‐based divider‐by‐2 22,23 outputs quadrature differential LO signals for the I‐path and Q‐path. Finally, the differential I/Q baseband signals successfully emerge for signal processing in poststage circuits, such as the IF2 filter 24,25 and variable gain‐controlled amplifier 26–28 …”

A 23‐ to 28‐GHz 5‐bit switch‐type phase shifter with 1‐bit calibration based on optimized ABCD matrix design methods for 5G MIMO system in 0.15‐μm GaAs

“…The received signal arrives at the antennas at different times and phases; thus, the energy of the synthesized signal cannot be maximized due to the interference of the different-phase signals after traveling through the low-noise amplifier (LNA) [2][3][4] and variable-gain amplifier (VGA). 5,6 The phase shifter is the key component to solve the above problem. The phase shift and gain of the signal in each channel can be controlled independently using the phase shifter.…”

“…There are parallel channels on the receiver, each connecting to a separate antenna. The received signal arrives at the antennas at different times and phases; thus, the energy of the synthesized signal cannot be maximized due to the interference of the different‐phase signals after traveling through the low‐noise amplifier (LNA) 2–4 and variable‐gain amplifier (VGA) 5,6 . The phase shifter is the key component to solve the above problem.…”