Hampus Malmberg

selected publications

1. TCAS-I

   A Control-Bounded Quadrature Leapfrog ADC

   Hampus Malmberg, Fredrik Feyling, and José M. de la Rosa

   IEEE Transactions on Circuits and Systems - I: Regular Papers, Feb 2024

   Abs DOI

   In this paper, the design flexibility of the controlbounded analog-to-digital converter principle is demonstrated. A band-pass analog-to-digital converter is considered as an application and case study. We show how a low-pass controlbounded analog-to-digital converter can be translated into a band-pass version where the guaranteed stability, converter bandwidth, and signal-to-noise ratio are preserved while the center frequency for conversion can be positioned freely. The proposed converter is validated with behavioral simulations on several filter orders, center frequencies, and oversampling ratios. Additionally, we consider an op-amp circuit realization where the effects of first-order op-amp non-idealities are shown. Finally, robustness against component variations is demonstrated by Monte Carlo simulations.

2. VLSI

   Design and Analysis of the Leapfrog Control-Bounded A/D Converter

   Fredrik Feyling,  Hampus Malmberg, Carsten Wulff, Hans-Andrea Loeliger, and Trond Ytterdal

   IEEE Transactions on Very Large Scale Integration (VLSI) Systems, Oct 2023

   Abs DOI

   This article presents analytical tools for high-level design of the leapfrog (LF) control-bounded analog-to-digital converter (CBADC). We derive closed-form design equations for parameterizing the analog system for a target signal-to-noise ratio (SNR) and bandwidth. Furthermore, we show how the parameterization can be modified to compensate for finite amplifier gain-bandwidth product (GBWP) and to control the signal swing at different nodes of the system. Behavioral circuit simulations are used to compare the LF CBADC to relevant continuous-time sigma–delta modulators (CT- Σ∆Ms) in terms of nominal performance and sensitivity to component variations, clock jitter, and finite GBWP. Simulations show that the nominal performance of the LF is similar to that of a CT- Σ∆M of the same loop-filter order and with the same number of quantization levels. The simple, modular structure, analytical stability guarantee, and single-bit quantizers make the LF an interesting alternative to conventional CT- Σ∆Ms.

3. ITA

   On sparsity by NUV-EM, Gaussian message passing, and Kalman smoothing

   Hans-Andrea Loeliger, Lukas Bruderer,  Hampus Malmberg, Federico Wadehn, and Nour Zalmai

   In Information Theory and Applications Workshop, Jan 2016

   Abs arXiv DOI

   Normal priors with unknown variance (NUV) have long been known to promote sparsity and to blend well with parameter learning by expectation maximization (EM). In this paper, we advocate this approach for linear state space models for applications such as the estimation of impulsive signals, the detection of localized events, smoothing with occasional jumps in the state space, and the detection and removal of outliers. The actual computations boil down to multivariate-Gaussian message passing algorithms that are closely related to Kalman smoothing. We give improved tables of Gaussian-message computations from which such algorithms are easily synthesized, and we point out two preferred such algorithms.