This paper presents a low-imbalance and inductor-less active balun. The large immittance of the parasitics increases gain and phase errors in single-ended-to-differential conversion at high frequencies. Positive feedback is effective in reducing these errors. However, there is a trade-off between the stability of the feedback and the imbalance correction. This paper analyzes this trade-off, and the common-mode rejection ratio (CMRR) was improved by adding a capacitor. Besides, we established the feedback loops for the imbalance correction are also available for bandwidth extension, that is the additional capacitor improves not only the CMRR but also the high-frequency gain. This peaking technique removes inductors that consume large chip areas. The balun was fabricated in a 0.18-$\mu \text{m}$CMOS process and achieved a small core area of 0.0058 mm2. In addition, a self-bias scheme using a current mirror was devised. It ensures a good bias current balance and reduces errors. The manufacturing variation of the fabricated baluns was statistically evaluated. To obtain the 99.7% limit of the CMRR, we extended the theory of the random CMRR to the complex plane. The measurement results demonstrated small errors within −0.1±0.2 dB and −0.18±1.17° including a variation of$\pm 3\sigma $from DC to 8.0 GHz.

This paper presents an area-efficient differential distributed amplifier using differential coupled inductors. The artificial transmission lines of the proposed distributed amplifier are modeled as differential transmission lines, and thus, it can be easily designed compared with other area reduction techniques. The dimensions of the coupled inductors have been optimized using a gradient descent algorithm with a scalable model of the coupled inductors. The proposed amplifier was designed using 1P5M 180 nm standard CMOS technology. Post-layout simulation results demonstrated a gain of 6.9 dB and a bandwidth of 20.2 GHz with 4.9 ps Nyquist group delay variation. A core area of the proposed amplifier was 0.28 mm2, which was the smallest value compared with previous works using similar processes.

We propose an immersive telepresence system for puppetry that transmits a human performer's body and facial movements into a puppet with audiovisual feedback to the performer. The cameras carried in place of puppet's eyes stream live video to the HMD worn by the performer, so that performers can see the images from the puppet's eyes with their own eyes and have a visual understanding of the puppet's ambience. In conventional methods to manipulate a puppet (a hand-puppet, a string-puppet, and a rod-puppet), there is a need to practice manipulating puppets, and there is difficulty carrying out interactions with the audience. Moreover, puppeteers must be positioned exactly where the puppet is. The proposed system addresses these issues by enabling a human performer to manipulate the puppet remotely using his or her body and facial movements. We conducted several user studies with both beginners and professional puppeteers. The results show that, unlike the conventional method, the proposed system facilitates the manipulation of puppets especially for beginners. Moreover, this system allows performers to enjoy puppetry and fascinate audiences.

We propose a system for transmitting a human performer's body and facial movements to a puppet with audiovisual feedback to the performer. The system consists of a head-mounted display (HMD) that shows the performer the video recording of the puppet's view, a microphone for voice capture, and photoreflectors for detecting the mouth movements of the human performer. In conventional puppetry, there is also the need for practice in the manipulation of the puppets to achieve good performance. The proposed telepresence system addresses these issues by enabling the human performer to manipulate the puppet through their own body and facial movements. The proposed system is expected to contribute to the development of new applications of puppetry and expand the interactivity of puppetry and the scope of entertainment.