Miniature CMOS Stacked Spiral-Coupled Directional Coupler With $-$67-dB Isolation and $-$ 0.8-dB Insertion Loss

Abstract

This letter proposes a miniature CMOS stacked spiral-coupled (SSC) directional coupler for a fully integrated CMOS transceiver to isolate the large transmit power from the transmitter to the receiver. It consists of two 90 • -rotated center-aligned SSC coils. The path center of one coil is aligned to the gap center of the other coil. The grounded secondary coil plays a role of ground shielding for reducing the insertion loss. Two capacitors are utilized for tuning the center frequency and isolation level. Fabricated in a standard CMOS process, it achieves an isolation of −67 dB, an insertion loss of −0.8 dB, and a coupling of −16.1 dB and only occupies 0.3 × 0.3 mm 2 of silicon area. To the authors' knowledge, this is the first CMOS directional coupler at the UHF band, with the smallest form factor when compared with other implementations of directional couplers.

A compact spiral‐coupled directional coupler for a mobile RFID reader via integrated passive technology

“…(a)] was only 0.43 dB at 910 MHz, including the insertion loss of the bonding wires, the cable, and the PCB lines. The measured coupling S 31 was 15.7 dB, as shown in Figure (b), which satisfies the 15 dB of the system requirements for an RFID reader with 20 dBm of output power . Figute 5(c) shows that the directional coupler achieved 27.2 dB of isolation at 910 MHz.…”

CMOS integrated low TX noise digital transmitter with tunable directional coupler for high performance UHF RFID reader

“…In order for high integration, low cost and low complexity, the integration of tunable directional coupler in a standard CMOS process is essential. A tunable CMOS transformer‐based topology for the directional coupler as an improving of our previous work is proposed as shown in Figure . It consists of two 90°‐rotated center‐aligned stacked square–spiral coils and tuning capacitors C P and C S .…”

SAW-less GNSS front-end amplifier with 80.4-dB GSM blocker suppression using CMOS directional coupler notch filter

“…In our previous work [8], we proposed a new topology of CMOS stacked spiral-coupled (SSC) directional coupler which fits the notch filter application in the proposed SAW-less GNSS front-end amplifier. The SSC directional coupler is based on the standard CMOS process.…”

“…In this paper, a GNSS front-end amplifier with 80.4-dB GSM blocker suppression is proposed based on our proposed CMOS stacked spiral-coupled (SSC) directional coupler in our previous published work [8]. In the proposed GNSS front-end amplifier, the SSC directional coupler is used as a notch filter to remove the GSM blocker.…”