Slew Rate Induced Distortion in Switched-Resistor Integrators

Jiraseree-amornkun, Amorn; Worapishet, A.; Klumperink, Eric A.M.; Nauta, Bram; Surakampontorn, W.

doi:10.1109/iscas.2006.1693127

Cited by 1 publication

(5 citation statements)

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“…3. This configuration embeds the nonlinear on-resistance of the MOS switches into a feedback loop, and thus, their nonlinear contributions are further suppressed to be negligibly small [5], [15], [16], [18]. In this case, the output voltage of the first-order S-2R filter can be given as (5) Again, when considering only the baseband operations, the second term containing the clock function is omitted.…”

Section: A Operation Principlementioning

confidence: 99%

“…The choices of the resistor value for and in an S-2R filter is important, since there is a tradeoff between the tuning range and the maximum slope of the output, which in turn determines the distortion performance [18]. From (4b), if we select at times larger than , the unity-gain frequency of the S-2R integrator can be determined in the form of (6) Assuming that the nominal frequency has been assigned at the duty cycle of 50%, or , the tuning range of the S-2R integrator derived from (6) is 7where is either the maximum or the minimum duty cycle of .…”

Section: B Resistor-value Selectionmentioning

confidence: 99%

“…This is particularly when a fast opamp response to a large input signal change is needed, typical in the operation of sampled-data circuits. During slewing, the feedback loop is effectively broken for some time, and it is instructive to predict when slewing occurs, so that its effects can be minimized [18]. Another potential source of distortion is time-dependent input resistances of the S-R filters, which may arise when the S-R circuits are driven by nonzero-impedance sources, e.g., of a driving mixer at the filters, and of each individual integrator within the S-R filters.…”

Section: Distortion Analysismentioning

confidence: 99%

“…The maximum slope in the first-order S-R filters can be found either by numerical evaluation of (5) or by using an analytical approximation method in [18]. In contrary to the integrators, they are dependent on , , and .…”

Section: Distortion Analysismentioning

confidence: 99%

“…One promising modification is to employ two sets of the switched-resistor (S-2R) combination as shown in Fig. 1(b), where it has been shown in [18] via analysis and simulation that the performance of the S-2R networks are less sensitive to slew limitations. Therefore, they offer a relaxed slew-rate requirement of the opamp than their S-1R counterparts.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical Analysis of Highly Linear Tunable Filters Using Switched-Resistor Techniques

Jiraseree-amornkun

Worapishet

Klumperink

et al. 2008

IEEE Trans. Circuits Syst. I

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In this paper, an in-depth analysis of switched-resistor (S-R) techniques for implementing low-voltage low-distortion tunable active-RC filters is presented. The S-R techniques make use of switch(es) with duty-cycle-controlled clock(s) to achieve tunability of the effective resistance and, hence, the RC time constant. The characteristics of two S-R networks utilizing one set (S-1R) and two sets (S-2R) of switch and resistor combinations are analyzed. It will be shown that the S-2R network outperforms the S-1R counterpart in terms of finite-slew-rate-induced distortion, frequency translation, and noise performance. In order to extend the tuning range, an S-R bank scheme is also described. The theoretical analysis was verified by an experiment on a 100-kHz first-order S-R filter prototype, implemented using discrete elements, where several advantages of the S-2R over the S-1R networks are demonstrated. Simulations of 10-MHz low-pass filters based on the S-1R and S-2R techniques in a standard 0.18-m CMOS process are also included for performance comparison in practical on-chip filter implementations.

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Section: A Operation Principlementioning

confidence: 99%

Section: B Resistor-value Selectionmentioning

confidence: 99%

Section: Distortion Analysismentioning

confidence: 99%

Section: Distortion Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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