Implementation of wideband integer and fractionaldelay element

Murphy, Niall; Krukowski, Artur; Kale, I.

doi:10.1049/el:19941157

Cited by 26 publications

(23 citation statements)

References 1 publication

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“…In Part II, we propose three reconstruction schemes that offer trade-offs between online redesign and reconstructor complexities. To reduce the complexity, these reconstructors utilize a two-rate based approach [66] which earlier has been used only for uniformly sampled signals [67][68][69][70][71][72][73][74][75]. However, here, the two-rate based approach is extended for the reconstruction of nonuniformly sampled signals which requires new design techniques.…”

Section: Low-complexity Reconstruction Schemesmentioning

confidence: 99%

Signal Reconstruction Algorithms for Time-Interleaved ADCs

Pillai¹

2015

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An analog-to-digital converter (ADC) is a key component in many electronic systems. It is used to convert analog signals to the equivalent digital form. The conversion involves sampling which is the process of converting a continuous-time signal to a sequence of discrete-time samples, and quantization in which each sampled value is represented using a finite number of bits. The sampling rate and the effective resolution (number of bits) are two key ADC performance metrics. Today, ADCs form a major bottleneck in many applications like communication systems since it is difficult to simultaneously achieve high sampling rate and high resolution. Among the various ADC architectures, the time-interleaved analog-to-digital converter (TI-ADC) has emerged as a popular choice for achieving very high sampling rates and resolutions. At the principle level, by interleaving the outputs of M identical channel ADCs, a TI-ADC could achieve the same resolution as that of a channel ADC but with M times higher bandwidth. However, in practice, mismatches between the channel ADCs result in a nonuniformly sampled signal at the output of a TI-ADC which reduces the achievable resolution. Often, in TI-ADC implementations, digital reconstructors are used to recover the uniform-grid samples from the nonuniformly sampled signal at the output of the TI-ADC. Since such reconstructors operate at the TI-ADC output rate, reducing the number of computations required per corrected output sample helps to reduce the power consumed by the TI-ADC. Also, as the mismatch parameters change occasionally, the reconstructor should support online reconfiguration with minimal or no redesign. Further, it is advantageous to have reconstruction schemes that require fewer coefficient updates during reconfiguration. In this thesis, we focus on reducing the design and implementation complexities of nonrecursive finite-length impulse response (FIR) reconstructors. We propose efficient reconstruction schemes for three classes of nonuniformly sampled signals that can occur at the output of TI-ADCs.iii Firstly, we consider a class of nonuniformly sampled signals that occur as a result of static timing mismatch errors or due to channel mismatches in TI-ADCs. For this type of nonuniformly sampled signals, we propose three reconstructors which utilize a two-rate approach to derive the corresponding single-rate structure. The two-rate based reconstructors move part of the complexity to a symmetric filter and also simplifies the reconstruction problem. The complexity reduction stems from the fact that half of the impulse response coefficients of the symmetric filter are equal to zero and that, compared to the original reconstruction problem, the simplified problem requires only a simpler reconstructor.Next, we consider the class of nonuniformly sampled signals that occur when a TI-ADC is used for sub-Nyquist cyclic nonuniform sampling (CNUS) of sparse multi-band signals. Sub-Nyquist sampling utilizes the sparsities in the analog signal to sample the signal at a lowe...

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Section: Low-complexity Reconstruction Schemesmentioning

confidence: 99%

Signal Reconstruction Algorithms for Time-Interleaved ADCs

Pillai¹

2015

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“…Using (24) to express (8) in matrix form and substituting the result in (11) followed by some algebraic manipulations, we get…”

Section: Online Design Ofmentioning

confidence: 99%

“…The TRB reconstructor, which extends the basic two-rate approach [24,25], helps to reduce the implementation complexity by splitting the regular reconstructor H n (z) in Fig. 2(b) into two subfilters namely F(z) and G (n) (z) as shown in Fig.…”

Section: M-channel Two-rate Based Reconstructorsmentioning

confidence: 99%

Efficient signal reconstruction scheme for M-channel time-interleaved ADCs

Pillai

Johansson

2013

Analog Integr Circ Sig Process

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In time-interleaved analog-to-digital converters (TIADCs), the timing mismatches between the channels result in a periodically nonuniformly sampled sequence at the output. Such nonuniformly sampled output limits the achievable resolution of the TI-ADC. In order to correct the errors due to timing mismatches, the output of the TI-ADC is passed through a digital time-varying finite-length impulse response (FIR) reconstructor. Such reconstructors convert the nonuniformly sampled output sequence to a uniformly spaced output. Since the reconstructor runs at the output rate of the TI-ADC, it is beneficial to reduce the number of coefficient multipliers in the reconstructor. Also, it is advantageous to have as few coefficient updates as possible when the timing errors change. Reconstructors that reduce the number of multipliers to be updated online do so at a cost of increased number of multiplications per corrected output sample. This paper proposes a technique which can be used to reduce the number of reconstructor coefficients that need to be updated online without increasing the number of multiplications per corrected output sample.Keywords Finite-length impulse response (FIR) filters · least-squares design · two-rate approach · periodically nonuniform sampling · time-interleaved analog-to-digital converters (TI-ADCs) · reconstruction filters.

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“…The multirate structure in [22] is proposed for designing FD filters in time domain. The input signal bandwidth is reduced by incrementing the sampling frequency.…”

Section: Multirate Structurementioning

confidence: 99%

Frequency-Based Optimization Design for Fractional Delay FIR Filters with Software-Defined Radio Applications

Díaz-Carmona

Dolecek

Ramirez-Agundis

2010

International Journal of Digital Multimedia Broadcasting

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A frequency-designed fractional delay FIR structure, which is suitable for software radio applications, is presented. The design method is based on frequency optimization of a combination of modified Farrow and mutirate structures. As a result the optimization frequency range is made only in half of desired total bandwidth. According to the obtained results the proposed fractional delay structure allows online desired fractional delay update, with a high fractional delay value resolution.

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Implementation of wideband integer and fractionaldelay element

Cited by 26 publications

References 1 publication

Signal Reconstruction Algorithms for Time-Interleaved ADCs

Signal Reconstruction Algorithms for Time-Interleaved ADCs

Efficient signal reconstruction scheme for M-channel time-interleaved ADCs

Frequency-Based Optimization Design for Fractional Delay FIR Filters with Software-Defined Radio Applications

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