A digital approach for automatic tuning of continuous-time high-q filters

Sumesaglam, T.; Karsilayan, A.I.

doi:10.1109/tcsii.2003.818363

Cited by 7 publications

(8 citation statements)

References 14 publications

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“…The technique proposed in this paper extends the work in [8] to high-order filters. Automatic tuning of the filter is accomplished using direct tuning method without separating individual biquad sections [18].…”

Section: Introductionmentioning

confidence: 80%

“…This assumption depends on the matching of the transconductors and capacitors, and ignores parasitics,which leads to inaccuracies [8]. Furthermore, this assumption is not applicable for certain types of filters such as active LC [15]- [17].…”

Section: Introductionmentioning

confidence: 99%

“…That saves the area of master filter, and eliminates switches and associated parasitics. Center frequency and of individual biquad sections are tuned by processing the phase information without any assumption on the peak gain [8]. Since the center frequency and of a biquadratic filter cannot be changed independently in most practical cases, simultaneous operation of both tuning loops may cause the filter to oscillate.…”

Section: Introductionmentioning

confidence: 99%

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A Digital Automatic Tuning Technique for High-Order Continuous-Time Filters

Sumesaglam

Karsilayan

2004

IEEE Trans. Circuits Syst. I

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A digital automatic tuning technique for high-order continuous-time filters is proposed. Direct tuning of overall response is achieved without separating individual biquad sections, eliminating switches and their parasitics. Output phase of each biquad section is tuned to known references, which are generated by a frequency synthesizer. The core tuning circuit consists of D flip-flops (DFF) and simple logic gates. DFFs are utilized to perform binary phase detection. Frequency and quality factor tuning loops for each biquad are controlled digitally, providing more stable tuning by activating only one loop at a given time. The tuning system was verified by a prototype sixth-order bandpass filter which was fabricated in a conventional 0.5 m CMOS process with 1.5 V power supply.

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Section: Introductionmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Digital Automatic Tuning Technique for High-Order Continuous-Time Filters

Sumesaglam

Karsilayan

2004

IEEE Trans. Circuits Syst. I

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“…Therefore, when implementation of continuous-time analog filters is targeted, the inclusion of an on-chip automatic control or tuning subsystem is invariably required [1][2][3][4]. This system should result in the automatic and continuous tuning of the filter whenever circuit parameters deviate in any way from their designed values.…”

Section: Introductionmentioning

confidence: 99%

Dynamic modeling of tunable analog integrated filters for a stability study of on-chip automatic tuning loops

Sarmiento

López

Alarcón

et al. 2009

Analog Integr Circ Sig Process

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Continuous-time filters with automatic tuning loops are nonlinear feedback systems that are potentially unstable. To ensure stability, particularly if the design of the loop controllers is to be improved, the appropriate linear dynamic modeling of the tunable filter, including control inputs, should be attained. This work aims to present a general dynamic modeling of continuous-time analog filters with automatic tuning capability. The general analysis leads to an equivalent small-signal linearized incremental model, from which transfer functions between output variables and control voltages are obtained. Subsequent to the analysis, it is possible to design compensated loops with enhanced stability and dynamic performance. By way of example, the modeling of a particular band-pass CMOS continuous-time analog filter is presented in this paper. Two transfer functions are derived: the transfer function between the output phase shift and the central frequency control voltage, and that between the output amplitude and the quality factor control voltage. These functions are required to properly tune the central frequency and quality factor parameters. This modeling makes it possible to propose an adaptive controller with improved stability and a possible implementation for such a controller. Finally, experimental results are shown for a CMOS 0.8 lm technology.

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“…Due to IC process variations and temperature dependence, all integrated analog filters must be tuned using some automatic Built-In-Self-Test-and-Correction (BISTAC) mechanism such as that in [11]. The active inductor in this paper offers the necessary tuning terminals for both frequency and Q.…”

Section: Introductionmentioning

confidence: 99%

A 5.4-GHz high-Q tunable active-inductor bandpass filter in standard digital CMOS technology

Xiao

Schaumann

2007

Analog Integr Circ Sig Process

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A transistor-only CMOS active-inductor with an all-NMOS signal path is presented. By tuning the varactor-augmented parasitic capacitance at the only internal node the circuit losses from submicron MOSFETs can be partially or fully compensated to permit realizing unlimited values of Q, with little frequency and no power-consumption penalties. Transistor-only second-order bandpass filters using the active inductor were built in the TSMC 0.18-lm CMOS process, and high filter Q was obtained by tuning the varactor. The highest center frequency measured was f 0 = 5.7 GHz for 0.2-lm gate lengths and the maximum repeatably measured Q was 665. Lower Qs can be obtained by reducing the capacitive compensation or by adjusting the circuit biasing. f 0 and Q are tunable via separate varactors. IIP 3 and input 1-dB compression point were simulated as 0.523 V PP and 0.128 V PP (-1.65 and -13.9 dBm from a 50-W source) at 5.7 GHz with Q = 100 and midband gain equal 4.7 dB. For the same conditions, the output noise and noise figure (R S = 50 kW) were simulated to be 0.8 lV/Hz 1/2 and 25.6 dB, respectively. The filter core occupies an area of 26.6 lm · 30 lm and dissipates 4.4 mW at 5.4 GHz from a 1.8-V power supply. As the circuits use only MOSFETs they are fully compatible with standard digital CMOS processes. f 0 statistics were obtained by measuring 40 chips at identical biasing condition.

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A digital approach for automatic tuning of continuous-time high-q filters

Cited by 7 publications

References 14 publications

A Digital Automatic Tuning Technique for High-Order Continuous-Time Filters

A Digital Automatic Tuning Technique for High-Order Continuous-Time Filters

Dynamic modeling of tunable analog integrated filters for a stability study of on-chip automatic tuning loops

A 5.4-GHz high-Q tunable active-inductor bandpass filter in standard digital CMOS technology

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