Programmable Order Multiple Feedback Band-Pass Active-RC filter for FSK Transceiver

An integrated programmable order multiple feedback (MFB) band-pass filter (BPF) implemented in 0.14 um CMOS technology is presented. The modular single ended filter has been used in an FSK transceiver, in both receiver (RX) and transmitter (TX). It is implemented by cascading different types of BP filters with different required bandwidth (BW) of RX and TX. A combination of Bessel and Butterworth filters to maximize stop-band rejection, optimize in-band flatness and minimize group delay variation is used. Each stage of the MFB filter draws 0.3mA of current from a 1.8V supply. A simple and efficient approach to trim center frequency which has minimum impact on area and parasitic components has been used. AC gain change of TX due to mismatches, parasitic and process and trimming has been compensated by a simple gain stage while it is budgeted in RX system SNR. The implemented 23.2MHz center frequency filters have been used in the FSK transceiver of a USB power delivery (PD) system, with a BW of 3.46MHz for RX filter and a BW of 1.3MHz for TX filter. The employed low current and small area architecture with its efficient trimming strategy meets the required performance of the FSK transceiver.

[1]  Siamak Delshadpour.  A Low Power CMOS gm-C Polyphase Filter for Low-IF GPS Receiver , 2018, 2018 25th IEEE International Conference on Electronics, Circuits and Systems (ICECS).

[2]  Xu Zhang,et al.  An FSK Transceiver for USB Power Delivery in 0.14-μm CMOS Technology , 2018, 2018 31st IEEE International System-on-Chip Conference (SOCC).

[3]  Congyin Shi,et al.  Highly Power-Efficient Active-RC Filters With Wide Bandwidth-Range Using Low-Gain Push-Pull Opamps , 2013, IEEE Transactions on Circuits and Systems I: Regular Papers.

[4]  Donggu Im,et al.  A 50–450 MHz Tunable RF Biquad Filter Based on a Wideband Source Follower With > 26 dBm IIP$_{3}$, +12 dBm P$_{1{\rm dB}}$, and 15 dB Noise Figure , 2015, IEEE Journal of Solid-State Circuits.

[5]  Andrea Baschirotto,et al.  A 30MHz 28dBm-IIP3 3.2mW fully-differential Sallen-Key 4th-order filter with out-of-band zeros cancellation , 2015, 2015 IEEE 13th International New Circuits and Systems Conference (NEWCAS).

[6]  Quan Hu,et al.  A 100–170MHz fully-differential Sallen-Key 6th-order low-pass filter for wideband wireless communication , 2016, 2016 International Conference on Integrated Circuits and Microsystems (ICICM).

[7]  Gangfeng Yan.  Design of Active Low-Pass Filter Based on Multiple Feedback Circuit , 2017, 2017 9th International Conference on Intelligent Human-Machine Systems and Cybernetics (IHMSC).

[8]  Horia Andrei,et al.  Sensitivity analysis of the Multiple FeedBack filter in non-sinusoidal regime , 2010, 2010 XIth International Workshop on Symbolic and Numerical Methods, Modeling and Applications to Circuit Design (SM2ACD).