Continuous‐time filter featuring Q and frequency on‐chip automatic tuning

Abstract

SUMMARYThe on-chip automatic tuning of digitally programmable continuous-time G m -C filters with a wide operation range employing a hybrid analog-digital master-slave scheme is reported in this work. The master system is implemented with a voltage-controlled filter (VCF) with the same programmable transconductance cells as the main filter to enhance the matching between master and slave. The frequency tuning method, for both analog and digital control, is based on a digital phase comparator included in the phase-locked loop achieving high-precision tunability. The digital frequency tuning is obtained with an error of ±4% and the maximum settling time when changing between two consecutive digital words is 0.3 s. Once the digital word is fixed, the analog tuning finely adjusts the value of the characteristic frequency to the reference and corrects for possible temperature variations with a settling time of 0.2 s. The analog frequency control covers the whole discrete step with a maximum error of ±5%. Furthermore, a magnitude-locked loop (MLL) Q-tuning block is simultaneously applied to the system in order to precisely control the quality factor of the G m -C filter by using an appropriate envelope detector. According to the obtained results, both post-layout simulation and experimental results, the adopted scheme has resulted as a useful and adequate solution to implement the complete auto-tuning system of digitally programmable continuous-time filters, including frequency and Q-control.

A power‐area‐efficient, 3‐band, 2‐RX MIMO, TD‐LTE receiver with direct‐coupled ADC

“…Because the CT ΔΣ ADC loop coefficients are chosen at the edge of the stable region to achieve maximum SNR, such variation may lead to an unstable operation and performance degradation. A tuning technique of the filter cutoff frequencies, as proposed in [19] and [20], is implemented to deal with the large tolerance of the integrated passive RC product during the start-up period of the receiver. In this work, a 3-bit programmable unit capacitors array is implemented as loop filter capacitors, which is automatically tuned to ensure that the coefficients stay near the theoretically optimal values.…”

Filter & hold: a mixed continuous‐/discrete‐time technique for time‐constant scaling

“…where e At is the state-transition matrix [25]. This representation is also valid for (6) during the time frame defined in (7). Outside the rectangular window the state vector is kept constant, holding the last integration value.…”

“…Capacitor multipliers , current scaling or very‐high active resistor implementations are different solutions that have been frequently employed in electronic systems for biology, in order to comply with the needed long time‐constants. However, these or other filters, even if purposely designed for low sensitivity to RC time constants , when integrated in CMOS, accuracy and flexibility for calibration are in general necessary to compensate for process and temperature variations . For G m ‐C filters, this generally involves digital‐to‐analog interfaces wherein fine‐resolution control is simultaneously correlated with increased area and power.…”

“…Simulation results and experimental measurements are provided to further validate the theoretical analysis for an F&H vector-filter prototype. variations [5][6][7][8][9][10]. For G m -C filters, this generally involves digital-to-analog interfaces wherein fineresolution control is simultaneously correlated with increased area and power.…”

On the usage of resonate and fire dynamics in the complex oscillation‐based test approach

“…Furthermore, the extension provides OBT with abilities, such as parametric testing, that would be hardly achievable otherwise. The ability to measure parameters is quite desirable in itself and could also open the way to automatic tuning strategies .…”