To further develop a low-power low-cost optical motion detector for use with traffic detection under dark and daylight conditions, we have developed and verified a procedure to use a Near Sensor Image Processing (NSIP) programmable 2-D optical sensor in a "1-D mode" to achieve the effect of using a cylindrical lens, thus improving the angle-of-view (AOV), the sensitivity, and usefulness of the sensor. Using an existing 256 x 256 element sensor in an innovative way, the AOV was increased from 0.4 to 21.3 in the vertical direction while also improving the sensitivity. The details of the sensor hardware architecture are described in detail and pseudo code for programming the sensor is discussed. The results were used to demonstrate the extraction of Local Extreme Points (LEPs) used for Time-To-Impact (TTI) calculations to estimate the speed of an approaching vehicle.

Linearity and efficiency are important parameters in determining the performance of any wireless transmitter. Pulse-width modulation (PWM) based transmitters offer high efficiency but suffer from low linearity due to image and aliasing distortions. Although the problem of linearity can be addressed by using an aliasing-free PWM (AF-PWM), these transmitters have a lower efficiency as they can only use linear power amplifiers (PAs). Moreover, an all-digital implementation of such transmitters is not possible. The aliasing-compensated PWM transmitter (AC-PWMT) has a higher efficiency due to the use of switch-mode PAs (SMPAs) but uses outphasing to eliminate image and aliasing distortions and requires a larger silicon area. In this study, the authors propose a novel transmitter that eliminates both aliasing and image distortions while using a single SMPA. The transmitter can be implemented using all-digital techniques and achieves a higher efficiency as compared to both AF-PWM and AC-PWM based transmitters. Measurement results show an improvement of 11.3, 7.2, and 4.3 dBc in the ACLR as compared to the carrier-based PWM transmitter (C-PWMT), AF-PWMT, and AC-PWMT, respectively. The efficiency of the proposed transmitter is similar to that of C-PWMT, which is an improvement of 5% over AF-PWMT.

All-digital implementations of PWM-based wireless transmitters are gaining popularity. Unlike baseband PWM, RF-PWM has relaxed filtering requirements and is preferred due to a smaller chip size. This paper is aimed to highlight the differences between polar and quadrature implementations of RF-PWM-based transmitters. Using mathematical models and simulations, performance of the two implementations is compared. The mathematical analysis indicates that the quadrature implementation is expected to have higher quantization noise compared to the polar because of the shorter duty cycles at maximum amplitude. The simulations, using a 10 MHz LTE uplink signal at 2 GHz carrier frequency, confirm this and also show the effect of RF pulse swallowing on the error vector magnitude (EVM).

This paper presents two novel transmitter architectures based on the combination of radio-frequency pulse-width modulation and multiphase pulse-width modulation. The proposed transmitter architectures provide good amplitude resolution and large dynamic range at high carrier frequency, which is problematic with existing radio-frequency pulse-width modulation based transmitters. They also have better power efficiency and smaller chip area compared to multiphase pulse-width modulation based transmitters.