A 10.7 MHz CMOS OTA-R-C bandpass filter with 68 dB dynamic range on-chip automatic tuning
01 Jan 1992-pp 66-67
TL;DR: In this article, a maximally flat 10.7-MHz fourth-order bandpass filter with 68 dB dynamic range was proposed, which is based on two biquadratic sections in cascade.
Abstract: The authors report a maximally flat 10.7-MHz fourth-order bandpass filter with 68 dB dynamic range. The bandwidth and ripple of the filter are 250 kHz and 0.5 dB, respectively. The third intermodulation distortion is below -40 dB for fully differential input signals up to 3.4 V peak-to-peak. The supply voltages are +or-2.5 V. The filter architecture is based on two biquadratic sections in cascade. >
Citations
More filters
TL;DR: In this article, a second order bandpass filter operating in current-mode has been implemented from two current-controlled conveyors in conjunction with one capacitor, which exhibits two bandpass outputs.
Abstract: A controlled active inductance implemented from two current-controlled conveyors in conjunction with one capacitor is introduced. Calculation, taking all the parasitics of the conveyors into account, shows that with this design the phase deviation from ideal is pushed up to very high frequency. A second order bandpass filter operating in current-mode has been implemented from this controlled inductance. This filter exhibits two bandpass outputs. One has unity gain and the other, which can be used for Q-tuning purpose, has a magnitude-gain at f/sub 0/ directly proportional to the Q-factor. An integrated circuit prototype of an IF receiver stage for the GSM cellular telephone has been designed from two cascaded identical second-order bandpass cells above. This circuit, which is intended to replace a surface acoustic wave (SAW) filter, was centered at 85 MHz. Simulation and measurement results are given for this prototype. They show interesting performances in conjunction with very low power consumption: less than 38 mW for the entire IF stage under /spl plusmn/2.5 V supply.
73 citations
TL;DR: In this article, the design of a tunable high-frequency fully integrable current-mode bandpass filter is presented using a complementary high-performance BiCMOS process.
Abstract: The design of a tunable high-frequency fully integrable current-mode bandpass filter is presented using a complementary high-performance BiCMOS process. The new architecture of this filter is based on impedance simulation and employs current controlled conveyors. The Q-factor and the center frequency can be electronically controlled with dc bias currents over a broad range of values, thus allowing easy tuning of this filter. An application to a mobile communication IF receiver channel centered at 85 MHz and with 1-MHz bandwidth based on the cascade of two identical second-order bandpass cells has been designed. Measurements show very interesting frequency performance (f/sub 0/ tunable in the range 30-120 MHz and Q from 1-140) in conjunction with low power consumption (25 mW for the fourth-order filter with /spl plusmn/2.5 V supplies).
68 citations
Patent•
07 Dec 1994TL;DR: In this article, a tuning system for an analog bandpass filter by tuning the characteristic integrator frequency (fc) of an OTA-C integrator by making the transconductance of the OTA amplifier (OTA) thereof equal to the aforementioned gain at that characteristic frequency is disclosed.
Abstract: Based on the insight that the voltage-to-current ratio or gain of a capacitor (Z) at a particular reference frequency is the product of its capacitance value with said reference frequency, a tuning system is disclosed which tunes the center frequency of an analog bandpass filter by tuning the characteristic integrator frequency (fc) of an OTA-C integrator by making the transconductance of the operational transconductance amplifier (OTA) thereof equal to the aforementioned gain at that characteristic frequency. Therefore, the tuning system includes a first tuning path in which the OTA, (or a replica thereof) is included and a second tuning path including another amplifier (B-OTA) "degenerated" by the capacitor (Z) so as to produce the required gain. The gains of both these tuning paths are then equalized by matching means (MM) generating a frequency tuning signal (VTF) which is applied to both OTA and OTA-C.
19 citations
Patent•
17 Mar 1995TL;DR: In this article, the authors proposed a tuning system that tunes the quality factor of a tunable filter to a desired quality factor value by tuning the passband gain of the filter.
Abstract: Based on the insight that the damping of a tunable filter is both related to its quality factor as to its passband gain, an inventive tuning system is proposed which tunes the quality factor of such a filter to a desired quality factor value by tuning the passband gain of the filter to a desired gain value. Such a tuning system is particularly useful in the field of OTA-C filters and consists of first (P1) and second (P2) tuning paths including such a tunable filter (BIQUAD) and fixed gain amplifiers (B-OTA1, B-OTA2). The gain of the latter amplifiers corresponds to the desired gain values. The tuning system further includes matching means (MM) for equalizing the gains in both tuning paths (P1, P2) by generating a quality factor tuning signal (VTQ) which is applied both to the tunable filter (BIQUAD) and to a replica thereof used as master filter in a data processing path. This matching means (MM) includes current rectifiers (C-REC1, C-REC2) implemented so as to use little hardware.
13 citations
TL;DR: A loss-control tuning loop for Q-enhanced LC filters based on a voltage-controlled filter (VCF) is presented and effective loss control of the filter over process tolerances is demonstrated.
Abstract: A loss-control tuning loop for Q-enhanced LC filters based on a voltage-controlled filter (VCF) is presented. The main factors affecting the tuning accuracy in this tuning scheme, including mismatches and frequency tuning errors, are discussed. The tuning scheme was implemented for a 1.5-V, 6-GHz Q-enhanced LC filter on a UMC 0.18-mum standard CMOS process. The design and measurement results are given. Effective loss control of the filter over process tolerances is demonstrated
7 citations
Cites background from "A 10.7 MHz CMOS OTA-R-C bandpass fi..."
...Related schemes for – filters can be found elsewhere [7]–[9]....
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References
More filters
TL;DR: In this article, a high-frequency large-signal very low-distortion voltage-to-current transducer is presented, where the transconductor noise is integrated over a bandwidth of 1 MHz.
Abstract: A high-frequency large-signal very low-distortion voltage-to-current transducer is presented. The total harmonic distortion (THD), for supply voltages of only +or-2.5 V, is smaller than 0.1% for fully differential input signals up to 2.4 V peak to peak (V/sub pp/). The dynamic range is on the order of 89 dB with the transconductor noise integrated over a bandwidth of 1 MHz. Moreover, this structure presents low sensitivity to transistor mismatches. An operational transconductance amplifier (OTA), based on this transconductor, has been used in an adjustable quality factor 1.8-MHz biquadratic continuous-time filter. The quality factor Q is controlled, from 2 to 50, with a novel current-source configuration. Both the OTA and the filter have been fabricated in a CMOS 3- mu m n-well process. >
90 citations
15 Feb 1989
TL;DR: In this article, a four-pole filter is modeled on two L-C resonators coupled by mutual inductance, resistively terminated at the input and output for maximum power transfer.
Abstract: The authors describe a continuous-time bandpass filter integrated in a 3- mu m CMOS technology, with an f/sub 0/ of 12.5 MHz and a 2% fractional bandwidth. The four-pole filter is modeled on two L-C resonators coupled by mutual inductance, resistively terminated at the input and output for maximum power transfer. Each resonator is simulated on the IC by two tunable integrators in negative feedback and is terminated by MOS resistors to define the filter bandwidth. Regulation of f/sub 0/ is obtained by locking an oscillating, consisting of a third identical integrator pair without termination resistors, to an externally supplied reference frequency. The circuits were fabricated on a double-metal, single-polysilicon, 3- mu m CMOS IC. Operation of the chip at a 12.5-MHz center frequency was verified, showing the desired 2% fractional bandwidth. >
46 citations
TL;DR: An experimental 10.7-MHz switched-capacitor bandpass filter was demonstrated that exhibits a 400-kHz bandwidth with a 42-MHz sampling rate in this article, where basic design issues of such highfrequency filters were also addressed with emphasis on dynamic range and power constraints.
Abstract: An experimental 10.7-MHz switched-capacitor bandpass filter is demonstrated that exhibits a 400-kHz bandwidth with a 42-MHz sampling rate. Basic design issues of such high-frequency filters are also addressed with emphasis on dynamic range and power constraints. A theoretical square relation between power and center frequency agrees well with experimental results. The sixth-order differential bandpass filter chip occupies 2 mm/sup 2/ using a 2.25- mu m gate double-poly CMOS technology. >
41 citations