The design of 3 rd /5 th order active RC Chebyshev low-pass filter (LPF) with reconfigurable bandwidth and gain is based on 55 nm CMOS technology. The filter is integrated into draft IEEE 802.11ax concurrent dual band four antenna transceiver analog baseband circuit. Programmable capacitor bank of the filter is used to adjust bandwidth. The typical bandwidth of receiving filter is 10/20/40 MHz, and that of transmitting filter is 12/24/50 MHz. Adjust the gain ranging from -10 to 18 dB in passband by programmable resistor bank. The current consumption of typical bandwidth of receiving filter is 2.08 mA at a 1.5 V supply and has properties of 10 MHz bandwidth (BW), 36 dB gain, -62 dBm input signal, -39 dB third intermodulation distortion (IMD3), 17.1 nV/√Hz equivalent input noise (EIN). As for transmitting filter, the current consumption of typical bandwidth is 1.25 mA at a 1.5 V supply and has the properties of 10 MHz BW, -6 dB gain, 0 dBm input signal, -38 dB IMD3, 75 nV/√Hz EIN. Area of the whole filter is 0.08 mm 2 . INDEX TERMS Active RC, analog baseband, low-pass filter.

A low phase noise quadrature LO-generator for dual-band wireless local area network (WLAN) applications is presented. The quadrature LO-generator is composed of a clock receiver, a CML divider, and two quadrature dividers for the dual-band, respectively. A clock receiver converts the single-ended clock to a differential signal. Then a quadrature divider with a 25% duty cycle generates four quadrature signals for mixers. The split-grounded architecture and multiply ground pads decrease the inductive component of ground impedance as well as the ground bounce of the single-ended input. The phase noise is −143dBc/Hz and −149dBc/Hz at 1MHz offset in the 2.4-GHz and 5-GHz bands, respectively.

In this paper, a 5.67-8.75 GHz LC VCO with small gain variation and reconfigurable buffer for 2.4 GHz-band WLAN applications is presented and implemented in a Semiconductor Manufacturing International Corporation (SMIC) 55 nm CMOS process. The VCO gain is a strong function of the capacitance. For wide frequency tuning range meaning the large gain variation. The gain calibration scheme is proposed to obtain small gain variation across the frequency range. This letter proposes a reconfigurable buffer with adjustable amplitude, low jitter, and small supply coupling issues. The results show the proposed gain calibration scheme is very effective. The measured phase noise at 6.69 MHz offset is -123.2 dBc/Hz at 4.9 GHz output frequency.

The demand for a local oscillator (LO) signal of high quality and integrity in local area network (WLAN) communication is growing with the increasing date rate. The LO signals for high data rate WLAN applications are desired to not only have proper shape waveforms and adequate voltage amplitude but also to achieve relatively stable and clean outputs with low phase noise and low spur. Fractional-N frequency planning is critical for a quadrature LO-generator, which is achieved by a single-sideband (SSB) mixer and multiple dividers since it can avoid the frequency pulling and alleviate the self-mixing and DC offset issues, while spur levels are easily increased due to harmonic mixing, imbalance, and leakage of the SSB mixer. This article proposes a simple and innovative quadrature LO-generator, which adopts a current-mode-logic (CML) inductive peaking (IP) circuit to improve phase noise and suppress spurious tones. Four types of LO delivery methods using IP circuits are proposed and compared. Among four methods, the CML-IP circuit presents the optimum performance for driving long wires of multi-mm length. Instead of previous digital spur cancellation, the CML-IP circuit achieves higher spur suppression, lower jitter, and a greater figure of merit (FoM). The quadrature LO-generator can be configured to either VCO mode or bypass mode supporting external VCO input. Implemented in 55 nm CMOS technology, the proposed quadrature LO-generator achieves −52.6 dBc spur suppression, −142 dBc/Hz phase noise at 1 MHz offset at the 4.8 GHz frequency, and −271 FoM. Furthermore, the quadrature LO-generator occupies an active area of 0.178 mm2 and consumes 23.86 mW.