Results 1  10
of
46
Spectral shaping of circuit errors in digitaltoanalog converters
 IEEE Trans. Circuits and Systems – II
, 1997
"... ..."
A 12mW ADC DeltaSigma Modulator With 80dB of Dynamic Range Integrated in a SingleChip Bluetooth Transceiver
 IEEE J. SolidState Circuits
, 2002
"... ..."
An approach to tackle quantization noise folding in doublesampling 61 modulation A/D converters
 IEEE Trans. Circuits Syst. II
, 2003
"... Abstract—61modulation is a proven method to realize high and very highresolution analogtodigital converters. A particularly efficient way to implement such a modulator uses doublesampling where the circuit operates during both clock phases of the masterclock. Hence, the sampling frequency is ..."
Abstract

Cited by 6 (4 self)
 Add to MetaCart
(Show Context)
Abstract—61modulation is a proven method to realize high and very highresolution analogtodigital converters. A particularly efficient way to implement such a modulator uses doublesampling where the circuit operates during both clock phases of the masterclock. Hence, the sampling frequency is twice the masterclock frequency. Unfortunately, path mismatch between both sampling branches causes a part of the quantization noise to fold from the Nyquist frequency back in the signal band. Therefore, the performance is severely degraded. In this paper, we show that the problem is reduced but not eliminated by employing multibit quantization. Next, we present an indepth solution for the problem. The approach consists of modifying the quantization noise transfer function of the overall modulator to have one or several zeros at the Nyquist frequency. This way the effect of noise folding can nearly be eliminated. It is shown that this can be implemented by a simple modification of one of the integrators of the overall modulator circuit. Finally, several design examples of singlebit and multibit modulators are discussed. Index Terms—Analogtodigital conversion, doublesampling, spectral shaping.
Higherorder Incremental DeltaSigma AnalogtoDigital Converters Summary of the Original Contributions of the PhD Thesis
"... Analogtodigital conversion, which takes continuoustime, continuous amplitude signals (voltage, temperature, sound, etc.) and converts them into a series of numbers to be used for digital signal processing, is becoming the key element of the scholarly and industrial applications of measurement and ..."
Abstract

Cited by 5 (1 self)
 Add to MetaCart
(Show Context)
Analogtodigital conversion, which takes continuoustime, continuous amplitude signals (voltage, temperature, sound, etc.) and converts them into a series of numbers to be used for digital signal processing, is becoming the key element of the scholarly and industrial applications of measurement and data acquisition,
0 Systematic Approach for Scaling Coefficients of DiscreteTime and ContinuousTime SigmaDelta Modulators
"... —In this paper we present a systematic method to scale the integrators output swings of modulator. It is shown that this scaling method preserves both the Noise Transfer Function and the Signal Transfer Function of the modulator. Examples are given to illustrate the effectiveness of the proposed met ..."
Abstract

Cited by 4 (3 self)
 Add to MetaCart
—In this paper we present a systematic method to scale the integrators output swings of modulator. It is shown that this scaling method preserves both the Noise Transfer Function and the Signal Transfer Function of the modulator. Examples are given to illustrate the effectiveness of the proposed method to alleviate circuit nonidealities.
FREQUENCY DOMAIN MINMAX OPTIMIZATION OF NOISESHAPING DELTASIGMA MODULATORS
"... Abstract. This paper proposes a minmax design of noiseshaping deltasigma (ΔΣ) modulators. We first characterize the all stabilizing loopfilters for a linearized modulator model. By this characterization, we formulate the design problem of lowpass, bandpass, and multiband modulators as minimizati ..."
Abstract

Cited by 4 (1 self)
 Add to MetaCart
(Show Context)
Abstract. This paper proposes a minmax design of noiseshaping deltasigma (ΔΣ) modulators. We first characterize the all stabilizing loopfilters for a linearized modulator model. By this characterization, we formulate the design problem of lowpass, bandpass, and multiband modulators as minimization of the maximum magnitude of the noise transfer function (NTF) in fixed frequency band(s). We show that this optimization minimizes the worstcase reconstruction error, and hence improves the SNR (signaltonoise ratio) of the modulator. The optimization is reduced to an optimization with a linear matrix inequality (LMI) via the generalized KYP (KalmanYakubovichPopov) lemma. The obtained NTF is an FIR (finiteimpulseresponse) filter, which is favorable in view of implementation. We also derive a stability condition for the nonlinear model of ΔΣ modulators with general quantizers including uniform ones. This condition is described as an H ∞ norm condition, which is reduced to an LMI via the KYP lemma. Design examples show advantages of our design. 1.
Quadrature Mismatch Shaping for DigitaltoAnalog Converters
"... Abstract—Quadrature sigma–delta analogtodigital converters require a feedback path for both the I and the Q parts of the complex feedback signal. If two separate multibit feedback digitaltoanalog converters (DACs) are used, mismatch among the unit DAC elements leads to additional mismatch noise i ..."
Abstract

Cited by 4 (0 self)
 Add to MetaCart
(Show Context)
Abstract—Quadrature sigma–delta analogtodigital converters require a feedback path for both the I and the Q parts of the complex feedback signal. If two separate multibit feedback digitaltoanalog converters (DACs) are used, mismatch among the unit DAC elements leads to additional mismatch noise in the output spectrum as well as an I/Q imbalance. This paper proposes new quadrature bandpass (QBP) mismatch shaping techniques. In our approach, the I and Q DACs are merged into one complex DAC, which leads to nearperfect I/Q balance. To select the unit DAC elements of the complex multibit DAC, the wellknown butterfly shuffler and tree structure are generalized towards a complex structure, and necessary constraints for their correct functioning are derived. Next, a very efficient firstorder QBP shaper implementation is proposed. Finally, the newly presented complex structures are simulated to prove their effectiveness and are compared with each other with respect to performance. Index Terms—Butterfly shuffler, mismatch shaping, quadrature bandpass (QBP), treestructured, 61 analogtodigital converters (ADCs). I.
A Quadrature Bandpass Modulator for Digital Radio
 ISSCC Dig. Tech. Papers
, 1997
"... Abstract—A quadrature bandpass modulator IC facilitates monolithic digitalradioreceiver design by allowing straightforward “complex A/D conversion ” of an imagereject mixer’s I and Q outputs. Quadrature bandpass modulators provide superior performance over pairs of real bandpass modulator ..."
Abstract

Cited by 3 (0 self)
 Add to MetaCart
(Show Context)
Abstract—A quadrature bandpass modulator IC facilitates monolithic digitalradioreceiver design by allowing straightforward “complex A/D conversion ” of an imagereject mixer’s I and Q outputs. Quadrature bandpass modulators provide superior performance over pairs of real bandpass modulators in the conversion of complex input signals, using complex filtering embedded in loops to efficiently realize asymmetric noiseshaped spectra. The fourthorder prototype IC, clocked at 10 MHz, converts narrowband 3.75MHz I and Q inputs and attains a dynamic range of 67 dB in 200kHz (GSM) bandwidth, increasing to 71 and 77 dB in 100 and 30kHz bandwidths, respectively. Maximum signaltonoise plus distortion ratio (SNDR) in 200kHz bandwidth is 62 dB. Power consumption is 130 mW at 5 V. Die size in a 0.8m CMOS process is 2.4 1.8 mm2. Index Terms—Analogdigital conversion, CMOS analog integrated circuits, complex filters, digital radio, bandpass sigma– delta modulation, switchedcapacitor circuits. I.
The Design of A HighBandwidth SigmaDelta Modulator”, EECS 247 Project report
, 2000
"... Abstract—The design of a highbandwidth Σ ∆ modulator which achieves 10 bits of resolution with a conversion rate of 20 MS/s is presented. The oversampling ratio is 16, requiring a sampling frequency of 320 MHz. The modulator is implemented as a fourthorder 211 cascade using switchedcapacitor in ..."
Abstract

Cited by 2 (0 self)
 Add to MetaCart
(Show Context)
Abstract—The design of a highbandwidth Σ ∆ modulator which achieves 10 bits of resolution with a conversion rate of 20 MS/s is presented. The oversampling ratio is 16, requiring a sampling frequency of 320 MHz. The modulator is implemented as a fourthorder 211 cascade using switchedcapacitor integrators, which is amenable to simple implementations in a CMOS process. The component values are scaled to maximize the dynamic range at the outputs of each integrator. In a typical 0.25µm process, we estimate the overall modulator power consumption to be around 40 mW. I.
Systematic design of doublesampling 61 A/D converters with a modified noise transfer function
 IEEE Trans. Circuits Syst. II, Exp. Briefs
, 2004
"... (ADCs) are sensitive to path mismatch which causes quantization noise to fold into the signal band. A recent solution for this problem consists of modifying the noise transfer function (NTF) of the modulator such that it has one or several zeros at the Nyquist frequency, next to those in the baseban ..."
Abstract

Cited by 2 (2 self)
 Add to MetaCart
(Show Context)
(ADCs) are sensitive to path mismatch which causes quantization noise to fold into the signal band. A recent solution for this problem consists of modifying the noise transfer function (NTF) of the modulator such that it has one or several zeros at the Nyquist frequency, next to those in the baseband. In this brief, we present a systematic design strategy for such ADCs. It consists of finding optimal pole positions for the modified NTF. This can be combined with optimizing the zeros as well. Next, we introduce several efficient structures that have enough degrees of freedom to realize the optimized pole positions. Index Terms—Analog–digital (A/D) conversion, double sampling, sigma–delta 61 modulation. I.