A Reconfigurable Analog Baseband Circuitry for LFMCW RADAR Receivers in 130-nm SiGe BiCMOS Process

Abstract

A highly reconfigurable open-loop analog baseband circuitry with programmable gain, bandwidth and filter order are proposed for integrated linear frequency modulated continuous wave (LFMCW) radar receivers in this paper. This analog baseband chain allocates noise, gain and channel selection specifications to different stages, for the sake of noise and linearity tradeoffs, by introducing a multi-stage open-loop cascaded amplifier/filter topology. The topology includes a course gain tuning pre-amplifier, a folded Gilbert variable gain amplifier (VGA) with a symmetrical dB-linear voltage generator and a 10-bit R-2R DAC for fine gain tuning, a level shifter, a programmable Gm-C low pass filter, a DC offset cancellation circuit, two fixed gain amplifiers with bandwidth extension and a novel buffer amplifier with active peaking for testing purposes. The noise figure is reduced with the help of a low noise pre-amplifier stage, while the linearity is enhanced with a power-efficient buffer and a novel high linearity Gm-C filter. Specifically, the Gm-C filter improves its linearity specification with no increase in power consumption, thanks to an alteration of the trans-conductor/capacitor connection style, instead of pursuing high linearity but power-hungry class-AB trans-conductors. In addition, the logarithmic bandwidth tuning technique is adopted for capacitor array size minimization. The linear-in-dB and DAC gain control topology facilitates the analog baseband gain tuning accuracy and stability, which also provides an efficient access to digital baseband automatic gain control. The analog baseband chip is fabricated using 130-nm SiGe BiCMOS technology. With a power consumption of 5.9~8.8 mW, the implemented circuit achieves a tunable gain range of −30~27 dB (DAC linear gain step guaranteed), a programmable −3 dB bandwidth of 18/19/20/21/22/23/24/25 MHz, a filter order of 3/6 and a gain resolution of better than 0.07 dB.

Single-Stage CMOS Operational Transconductance Amplifiers (OTAs): A Design Tutorial

“…Operational transconductance amplifiers (OTAs), which convert an input voltage to an output current, play crucial roles in a wide range of electronic systems. G m -C filters, based on OTAs, have been employed in sensor interface integrated circuits (ICs) [1][2][3], biopotential recording circuits [4][5][6], and wireless communication integrated circuits (ICs) [7][8][9] to attenuate interferers with a wide tuning range of cut-off frequencies. OTA-based integrators with an inherent high gain and low-pass frequency response have been used in delta-sigma analog-to-digital converters (ADCs) [10][11][12].…”

A 130-to-220-GHz Frequency Quadrupler with 80 dB Dynamic Range for 6G Communication in 0.13-μm SiGe Process

“…Various solid-state circuits have been implemented in SiGe technologies [1][2][3][4], such as the CML divider (Current Mode Logic divider) [5], transimpedance amplifier [6], voltage-controlled oscillators (VCOs) [7], bandpass filter [8], and switch [9]. Including the above various blocks based on the SiGe BiCMOS process, they have been widely used in various sub-THz systems, including radar receivers [10], 5G transceiver [11], and high-resolution imaging device [12].…”

Monopulse Antenna Based on Singular Spoof Surface Plasmon Polariton Structure for Angle Measurement

“…Moreover, it provides rich information when applying in the radar systems. The antennas may obtain the distance of the detected object [1,2], the direction to the objects [3], and velocity of the objects [4,5] by analyzing parameters of the echo signals [6], where information is attached with the change of propagation properties of the radio waves [7].…”