Abstract—This paper presents a state-variable bandpass filter with wide frequency range coverage and wide Q tuning range. The state-variable filter was chosen because it can be easily extended to a universal biquad filter structure [1]. A digital tuning technique with a novel Q-tuning algorithm was implemented in Verilog-A, and a real-time tuning of center frequency fc and Q was demonstrated. The technique is accurate as long as there is no phase error in the system. In the presence of phase error and for high Q filter requirements, tuning algorithm based on magnitude detection was demonstrated. A bandpass filter was simulated in 45nm CMOS technology using RF components for more accurate modeling of the fets. Filter simulation results showed frequency range coverage from 520MHz to 2.2GHz, and Q range from 2 to 400. For a filter with Q=33, simulation results showed a dynamic range of 55dB over a 3dB bandwidth at fc=1.5GHz. The current consumption of the designed filter is 75mA at 1.2V.

 

Index Terms—programmable filter, calibration, biquad, analog signal processing

Cite: Alma Delić-Ibukić, Steven Mikes, Zhiguo Lai, and Dev V. Gupta, "Programmable State-Variable Filter with Wide Frequency and Q Tuning Range," International Journal of Electronics and Electrical Engineering, Vol. 3, No. 3, pp. 207-211, June 2015. doi: 10.12720/ijeee.3.3.207-211