A 2.7 V CMOS dual-mode baseband filter for GSM and WCDMA

Hollman, T.; Lindfors, S.; Salo, T.; Lansirinne, M.; Halonen, K.

doi:10.1109/iscas.2001.921856

Cited by 11 publications

(6 citation statements)

References 2 publications

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“…The real pole can be extracted from the filter transfer function and realized with an RC pole at the filter input, as shown in Fig. 4.2 and formerly presented, for example, in [26]. Obviously, another option is to place an RC pole at the filter output.…”

Section: Real Pole Extractionmentioning

confidence: 99%

Prototype and Synthesis of Active Filters

Saari¹,

Ryynänen

Lindfors

2012

Analog Circuits and Signal Processing

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At the very beginning of the filter design, an appropriate filter transfer function and the order of the filter have to be selected. In radio receivers, the bandwidth and, particularly, the selectivity requirement for channel-select and anti-aliasing filtering are determined by the wireless application being targeted, the specified or expected interferers scenario, and the performance of the ADC, as discussed in Chap. 2. The bandwidth and selectivity requirements of the analog baseband filter further depend on the receiver architecture adopted and the preceding filter stages. The filter transfer function and the order of the filter are then chosen according to the given selectivity requirement. In addition, for example, the passband flatness and phase response characteristics that are required have to be taken into account. In active filter implementations, the minimization of filter stages (i.e. the order of the filter) is typically beneficial in terms of noise, power consumption, and complexity. Therefore, it is important also to consider the feasibility of the active filter realization, as well as the performance requirements set for the filter block, before finally deciding on the filter prototype.The next step is to synthesize the filter realizing the selected transfer function. Broadly speaking, there are two dominant approaches to synthesizing active continuous-time filters [1][2][3]. Active filters can be realized by biquads connected in a cascade in which each biquad implements a complex pole pair (with or without zeros) of the transfer function. Another approach is to simulate the operation of an LC ladder prototype filter. Lossless doubly terminated LC ladder filters are able to realize a large number of conventional filter transfer functions, such as Butterworth, Chebyshev, and Elliptic approximations. In addition, they are known to have a low sensitivity in their passband frequency response to component value variations [1][2][3][4][5][6][7][8][9][10][11]. The operation of LC ladder filters can be simulated with active filter realizations in such a way that a one-to-one correspondence between the reactive elements of the LC ladder and the integrators of the corresponding active realization is maintained [5,8]. As a result, these active filters inherit the low-sensitivity behavior [1-3, 5, 6, 8, 10-13]. Considering the operational simulation of LC ladder filters, the signal flow graph (SFG) method is one of the most widely used V. Saari et al.,

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Section: Real Pole Extractionmentioning

confidence: 99%

Prototype and Synthesis of Active Filters

Saari¹,

Ryynänen

Lindfors

2012

Analog Circuits and Signal Processing

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“…In multistandard filter designs, the op-amp bias current is also often reduced for operation at lower bandwidths. This requires specialized op-amp designs, where frequency compensation is also bias-dependent [20,21]. Other papers have also considered power consumption control issue [3,17]; switchable op-amps are proposed to reduce power consumption in [17].…”

Section: Circuit Techniques For Analogue Baseband Filtersmentioning

confidence: 99%

“…But they are different from Gm-C filters, as active-Gm-RC filters use resistors, Gm-Op-amp-C filters use op-amps, and both of them retain active-RC filter structures. Several designers have also taken advantage of the inherently good linearity of a passive-RC section, by using this as the input filter section providing a single real-axis pole of a higher-order active-RC [20,21] or Gm-C [30,32] filter response. The RC section provides a useful degree of prefiltering to reduce the level of out-of-band interferers reaching the active sections of the filter.…”

Section: Gm-c Filtersmentioning

confidence: 99%

“…The maximum size of resistors and capacitors for low-frequency operation is limited by chip area restrictions. Many designers therefore use schemes that include control of both R and C (for active-RC filters) [2,20,21] or g m and C (for Gm-C filters) [4,30]. For example, an active-RC filter could employ separate resistors for coarse frequency selection at each nominal cutoff frequency, and a binary capacitor array to achieve "fine tuning" to compensate for process variations at each cut-off frequency.…”

Section: Tuning Of Analogue Baseband Filtersmentioning

confidence: 99%

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Multistandard Analogue Baseband Filters for Software-Defined and Cognitive Radio Receivers

Sun

Moritz

Zhu

2011

Circuits Syst Signal Process

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Analogue baseband filters are an important circuit for channel select and anti-aliasing in wireless and mobile communication systems. For software and cognitive radio, they must be widely tunable and reconfigurable to accommodate existing, emerging, and future wireless and mobile standards. In this paper, design considerations of tunable and programmable filters for highly integrated multistandard receivers are presented. General background of multistandard integrated receivers and design challenges of analogue baseband filters are given. Circuit techniques for baseband filter design including the widely used active-RC and Gm-C circuits are described. Filter structures and design methods for high-order baseband filters are reviewed. On-chip tuning issues and methods are discussed. Results and performances of some published design examples are summarized. Future directions are also pointed out.

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“…Since the formed RC pole is passive, it attenuates linearly out-of-band interfering signals before the active devices in the filter. Thus, the passive RC pole at the filter input increases considerably the out-of-band linearity of the baseband filter compared to an active filter implementation without a passive pole at the mixer output [5], [6]. Decreasing the pole frequency is obviously beneficial from the filter out-of-band linearity point of view.…”

Section: Mixer-baseband Filter Interfacementioning

confidence: 99%

SiGe BiCMOS High Linearity Mixers for Base-Station Applications

Tikka¹,

Saari²,

Halonen³

et al. 2008

2008 European Microwave Integrated Circuit Conference

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This paper describes design issues related to high linearity SiGe BiCMOS active mixers, which are primarily targeted for WCDMA base-station applications. The effect of different mixer components to overall mixer dynamic range is described, and the measurement results from four different implementations are given to support this discussion. The different mixers are implemented using the same process as part of a complete receiver and thus the interface to baseband filter has been taken into account in the performance analysis. Since one of the goals in the mixer design has been to maximize the mixer bandwidth, the frequency limitations of different alternatives are discussed throughout the paper.

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A 2.7 V CMOS dual-mode baseband filter for GSM and WCDMA

Cited by 11 publications

References 2 publications

Prototype and Synthesis of Active Filters

Prototype and Synthesis of Active Filters

Multistandard Analogue Baseband Filters for Software-Defined and Cognitive Radio Receivers

SiGe BiCMOS High Linearity Mixers for Base-Station Applications

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