30-100 MHz npn-only variable-gain class AB companding-based filters for 1.2 V applications

El-Gamal, M.N.; Baki, R.A.; Bar-Dor, A.

doi:10.1109/isscc.2000.839726

Cited by 9 publications

(8 citation statements)

References 6 publications

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“…3 can be used when the internal bias can be controlled from the input. Log-domain filters [2]- [5] have this property and will be used here to illustrate the principle. Fig.…”

Section: A Log-domain Filtermentioning

confidence: 99%

Noise and power reduction in filters through the use of adjustable biasing

Krishnapura

Tsividis

2001

IEEE J. Solid-State Circuits

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A technique that enables the variation of bias currents in a filter without causing disturbances at the output is presented. Thus, the bias current can be kept at the minimum value necessary for the total input signal being processed, reducing the noise and power consumption. To demonstrate this approach, a dynamically biased log-domain filter has been designed in a 0.25-m BiCMOS technology. The chip occupies 0.52 mm 2 . In its quiescent condition, the filter consumes 575 W and has an output noise of 4.4 nA rms. Signal-to-noise ratio greater than 50 dB over 3 decades of input and total harmonic distortion less than 1% for inputs less than 2.5 mA peak are achieved. The bias can be varied to minimize noise and power consumption without disturbing the output. Index Terms-Analog filters, companding, dynamic bias, logdomain.Yannis P. Tsividis

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“…3 can be used when the internal bias can be controlled from the input. Log-domain filters [2]- [5] have this property and will be used here to illustrate the principle. Fig.…”

Section: A Log-domain Filtermentioning

confidence: 99%

Noise and power reduction in filters through the use of adjustable biasing

Krishnapura

Tsividis

2001

IEEE J. Solid-State Circuits

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“…This V/I converter is a modified version of the CMOS I/I converter discussed in [15]. Analysis of the feedback loop composed of Q 1 -Q 5 shows that [6]. Transistor Q 8 carries the same current as Q 2 .…”

Section: The Input and Output Interface Circuitrymentioning

confidence: 99%

“…[5]- [11]), the filter in this paper consists of a cascade of first and second-order sections ( Fig. 1), all employing identical nonlinear integrators.…”

Section: Filter Structure and Specificationsmentioning

confidence: 99%

A low-power, 5-70MHz, 7th-order filter with programmable boost, group delay, and gain using instantaneous companding

Baki

El-Gamal

2001

Proceedings of the 2001 International Symposium on Low Power Electronics and Design - ISLPED '01

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A seventh-order 0.05 o equiripple linear-phase continuous-time filter employing, for the first time, instantaneous companding, was designed and integrated in a mature bipolar process. The amount of boost (up to 13dB) and group-delay adjustment (30%) are digitally programmable. The DC gain is controllable up to 10dB, and the -3dB frequency (f c ) is tunable from 5 to 70MHz. The output swing for 1% THD is higher than 100mV pp , with a 1.5V supply. The filter consumes very low power (5-13mW for f c = 70MHz) compared to conventional implementations (e.g. 120mW for f c = 100MHz [1]). INTRODUCTIONThe continuous decrease of the supply voltages of modern integrated circuit technologies often necessitates an increase in the power consumption of conventional analog circuit processors, in order to maintain the same Dynamic Range (DR) and chip area for a given bandwidth [2]. To mitigate this restriction, the use of companding-based signal processors was proposed [3]- [4]. The last ten years have seen a growing interest in employing companding for continuous-time filtering. This was paralleled by the design and fabrication of several integrated log-domain filter circuits in a variety of technologies (e.g.[5]- [11]). These implementations were mostly low-order filters for proof of concept and / or performance exploration; they did not target particular applications or specifications. In order to gain industrial acceptance, the performance of companding-based filters needs to match, if not exceed, the performance of conventional filtering schemes, and should be evaluated in the context of concrete applications. Recently, a micropower log-domain filter for the Digital European Cordless Telephone (DECT) standard was reported [10]. Hard-disk-drive (HDD) read channels is another application where the requirements on filtering is constantly on the rise in terms of power consumption, tunability, speed, and robustness [12]. The objective of the work presented in this paper is to design a companding-based prefilter for HDD applications which exceeds state-of-the-art bipolar/BiCMOS designs in terms of voltage supply and power consumption (5mW without boost and equalization for f c = 70MHz versus 120mW for f c = 100MHz in [1]), while satisfying the requirements of partial response maximum likelihood (PRML) read channel front-ends. In servo mode, the filter has a cutoff frequency as low as 5MHz and dissipates less than 500µW. Figure 1 shows the overall structure of the 7 th -order filter presented in this paper, along with a summary of the system specifications (details in Section 5). The input signal is compressed before being processed, which ensures signal integrity over a large range of signal levels. At the output, the signal is expanded to restore its DR. When the compression / uncompression are logarithmic / exponential, the resulting filter is known as a "log-domain filter" [13]. CONCEPT OF LOG-DOMAIN FILTERINGThe concept of log-domain filtering is illustrated in Fig. 2 (a) for a simple first-order filter. The input signal v IN ,...

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“…Without the need for conventional circuit linearization techniques, logdomain filter circuits have a simple and elegant structure, and hold potential to run at high frequencies and operate from low power supplies [1][2][3][4][5][6][7][8][9][10]. An important property of log-domain filtering is that it uses companding [3,4], whereby the signals are compressed logarithmically at the input stage before being processed and then expanded exponentially at the output stage.…”

Section: Introductionmentioning

confidence: 99%

“…This makes it possible for log-domain circuits to operate with very low supply voltage without sacrificing the dynamic range [10]. Log domain filters are of interest, mainly due to their suitability for low voltage, low power, low impedance levels, large dynamic range, high frequency applications and for being electronically tunable [1][2][3][4][5][6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

A new 5th-order differential type class-AB log-domain elliptic lowpass filter for video frequency applications

Kirçay

Çam

2009

Analog Integr Circ Sig Process

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This paper proposes a new current-mode 5th-order differential type class-AB log-domain elliptic lowpass filter for video frequency applications. The design is based on the state-space synthesis method. The proposed filter has 5.75 MHz cut-off frequency with maximum 0.177 dB passband ripple and attenuation greater than 40 dB at 7.88 MHz. Only BJTs and grounded capacitors were used, and operated with single power supply of 2.5 V. Since the parameters of proposed filter are tunable, it is easy to control of cut-off frequency. This adjustment is accomplished by changing external currents. SPICE simulations are given to confirm the theoretical analysis. For this purpose, the filter is simulated by using both idealized BJT models and AT&T CBIC-U2 type transistors.

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30-100 MHz npn-only variable-gain class AB companding-based filters for 1.2 V applications

Cited by 9 publications

References 6 publications

Noise and power reduction in filters through the use of adjustable biasing

Noise and power reduction in filters through the use of adjustable biasing

A low-power, 5-70MHz, 7th-order filter with programmable boost, group delay, and gain using instantaneous companding

A new 5th-order differential type class-AB log-domain elliptic lowpass filter for video frequency applications

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