A Closed-loop Reconfigurable Analog Baseband Circuitry with Open-loop Tunable Notch Filters to Improve Receiver Tx leakage and Close-in Blocker Tolerance

Xu Cheng (Corresponding author), Feng-Jun Chen, Liang Zhang, Hao Gao, Jiang-An Han, Jing-Yu Han, Yang Yu, Xian-Jin Deng

Research output: Contribution to journalArticleAcademicpeer-review

2 Citations (Scopus)
78 Downloads (Pure)

Abstract

This paper presents an analog baseband (ABB) circuit in a 0.13 μm SiGe technology for transmitter leakage cancellation and close-in blocker suppressions in fully duplex (FD) frequency-modulated continuous-wave (FMCW) radar. This ABB comprises a programmable gain amplifier (PGA) and a cascaded LPF/Notch hybrid, which incorporates a closed-loop (CL) reconfigurable low-pass filter (LPF) and an open-loop (OL) tunable notch filter. The adopted key topologies include active-RC bi-quads and Gm-C ones. In an FD FMCW transceiver, Tx leakage and close-in blockers are difficult to be eliminated in the RF domain, especially when leakage/blockers are very close to desired signals or even in-band in the frequency domain. This LPF/notch hybrid is proposed to solve this issue. The LPF and PGA provide bandwidth (BW)/gain programmability, while the Gm-C bi-quad provides adaptable center frequency for a notch filter. With this adaption, the notch filter could be adjusted to match the leakage/blocker offset frequency. Thus, digitally discrete programmability and analog continuous tuning capability are combined in this solution for improving the overall front-end interference robustness without de-sensitizing the Rx. Furthermore, the order of LPF/notch hybrid is programmable from 2 to 10 with a step of 2 for different rejection levels of interferences. The measured chip achieves a -3dB bandwidth of 6 21 MHz with 4-bit digital control and 1 MHz/step programmability, and a voltage gain of 0 70 dB with 9-bit digital control (3-bit from pre-amplifier, and 6-bit from PGA with 1 dB/step). With the condition of 15 dB gain, output P-1dB is 11.8 dBm@3MHz, and the output IP3 is 20.8 dBm@3MHz.
Original languageEnglish
Article number9601299
Pages (from-to)839-843
Number of pages5
JournalIEEE Transactions on Circuits and Systems II: Express Briefs
Volume69
Issue number3
Early online date2021
DOIs
Publication statusPublished - 1 Mar 2022

Keywords

  • Interference
  • Electronics packaging
  • Notch filters
  • Gain
  • Computer architecture
  • Topology
  • Mixers
  • PGA.
  • Gm-C filter
  • notch filter
  • Analog baseband
  • fully duplex
  • FMCW
  • Fully duplex
  • PGA
  • Notch filter

Fingerprint

Dive into the research topics of 'A Closed-loop Reconfigurable Analog Baseband Circuitry with Open-loop Tunable Notch Filters to Improve Receiver Tx leakage and Close-in Blocker Tolerance'. Together they form a unique fingerprint.

Cite this