Technological limitations have restricted the capability of older generation in-the-ear (ITE) hearing aids to closely match prescribed real ear gain/frequency responses. Newer technology, widely available in currently marketed ITE hearing aids, has considerably improved this capability. Data for 60 ears are presented comparing the real ear insertion gain (REIG) actually achieved to the target R...

This paper presents a combined power amplifier system consisting of a linear amplifier unit with a switchedmode (class D) current dumping stage arranged in parallel. With this topology, the fundamental drawback of conventional linear power amplifiers—the high loss—is avoided. Compared to a pure class D (switching) amplifier, the presented system needs no output filter to reduce the switching fr...

The previous literature on tuned power amplifiers has not made clear the fundamental differences between amplifiers in which the output device acts 1) as a current source, or 2) as a switch. Previous circuits have often operated in contradiction to their design assumptions, resulting in the need for “cut-and-try” design. The new class of amplifiers deseribed here is based on a load network synt...

In this paper, the research advances in silicon based millimeter wave and THz ICs in the State Key Laboratory of Millimeter Waves is reviewed, which consists of millimeter wave amplifiers, mixers, oscillators at Q, V and W and D band based on CMOS technology, and several research approaches of THz passive ICs including cavity and filter structures using SIW-like (Substrate Integrated Waveguide-...

The stability margin of an audio power amplifier is reduced by a pole in the loopgain transfer function caused by shunt capacitance in the loudspeaker load. The problem is most severe in amplifiers with output stages that have a high output impedance before feedback. Because MOSFET devices can have an output impedance that is much higher than BJT devices, amplifiers with WFlT output stages are ...

Active filters play important role in communication systems. They can be obtained and constructed by different methods. Recently, there is a tendency of designing current-mode circuits using unity-gain active elements such as, CFOAs, CCIIs, etc. instead of classical infinite gain operational amplifiers in active filter design. This paper presents transresistance multifunction filter realization...

In this paper we look at the load presented to audio amplifiers by real transducers. We consider the power losses in Class-AB and Class-D amplifier topologies, and determine that in order to predict efficiency it is necessary to consider the amplifier/transducer combination. The ability of the class-D amplifier to recycle quadrature load current offers new ways to improve efficiency. INTRODUCTI...