A digital control mechanism for the delay of a dual-microphone analog beamformer

The microelectronic industry is driven by the continuous demand for processing capabilities and performance. As such, most processing is performed nowadays in a digital fashion. Analog however is not to be neglected. A key feature in modern mixed-signal processing is wide-range tuning of the analog processing sections. One step forward is the implementation of digitally programmable analog. The aim of this paper is to illustrate the digital tuning mechanism on the analog beamformer of a dual-microphone array. Analog processing consists of having one microphone signal delayed by an allpass filter, in order to be synchronized to the other microphone signal. A Gm-C filter implementation was considered, and filter tuning was performed via the transconductor bias current. Digital control of the bias current was implemented with a current digital to analog converter, enabling a straightforward and simple control mechanism. Transistor-level simulation results validate the proposed design.

[1]  R. Sarpeshkar,et al.  Low-Power Single-Loop and Dual-Loop AGCs for Bionic Ears , 2006, IEEE Journal of Solid-State Circuits.

[2]  Toshio Adachi,et al.  An AI-calibrated IF filter: a yield enhancement method with area and power dissipation reductions , 2002, Proceedings of the IEEE 2002 Custom Integrated Circuits Conference (Cat. No.02CH37285).

[3]  Robert Groza,et al.  Current-mode log-domain programmable gain amplifier , 2014, 2014 IEEE International Conference on Automation, Quality and Testing, Robotics.

[4]  Darko Mitic,et al.  Phase-Synchronizer based on gm-C All-Pass Filter Chain , 2012 .

[5]  Carlos Fernández Scola,et al.  Direction of arrival estimation : A two microphones approach , 2010 .

[6]  Deog-Kyoon Jeong,et al.  An all-analog multiphase delay-locked loop using a replica delay line for wide-range operation and low-jitter performance , 2000, IEEE Journal of Solid-State Circuits.

[7]  Edgar Sanchez-Sinencio,et al.  CMOS transconductance amplifiers, architectures and active filters: a tutorial , 2000 .

[8]  A. Gogoi,et al.  A 0 . 8 V CMOS OTA and Its Application in Realizing a Neural Recording Amplifier , 2014 .

[9]  Edgar Sanchez-Sinencio,et al.  A CMOS transconductance amplifier architecture with wide tuning range for very low frequency applications , 2002 .

[10]  Sorin Hintea,et al.  A Programmable Gain Amplifier for Automated Gain Control in Auditory Prostheses , 2010 .

[11]  Peter B. Kenington.  RF and Baseband Techniques for Software Defined Radio , 2005 .

[12]  Sorin Hintea,et al.  An Electronically Tunable Transconductance Amplifier for Use in Auditory Prostheses , 2015 .