RF and Analog Electronics experiments
This article aims to explain why impedance matching is required for extracting the maximum gain from transistors, as is typically required in RF applications. We start by using a rough model of the transistor's input and then perform a full small-signal analysis, proving the argument in depth. Transistors
This article explores three methods to determine a PCB’s effective dielectric constant by analyzing resonance and reflection peaks, enabling accurate permittivity extraction for design and simulation.
Low-pass filtering is key for noise reduction, sensor averaging, and controller stabilization. This article introduces a second-order low-pass filter, adjustable via complex pole placement in the Z-plane for optimal resonance and Q factor.
Crystal resonators are essential for high-stability oscillators, offering low cost, precision, stability, and low-power consumption. This article explores the extraction of their electrical parameters to optimize performance in electronic design.
This study focuses on the design, construction, and evaluation of a 50 Ohm loop antenna for the 434 MHz band. Beginning with a full-wave round loop antenna, the design evolves into a 2:1 rectangular loop, with experiments conducted to assess prototype performance and the effects of material choices.
Reverse biased base-emitter junctions are effectively used as noise sources, with a great amount of ENR (Excess Noise Ratio) originating from the intrinsic behavior of avalanche and zener operation. This article is a compilation of measurements in a noise source prototype - designed for evaluation of a subcircuit for another
Active probes are a must when designing high frequency topologies. This article covers a modification procedure to adapt HP 1152A active probes into modern oscilloscopes. HP 1152A probe (picture from the internet). The HP1152A is a 2.5 GHz active probe, with 100 kΩ @ 0.6 pF input impedance.
Remote controls for garage doors are designed as low-cost devices, using very low part counts, and with small size for portability. These constraints commonly reflect in an RF system with low performance (low range and/or low battery life). This article explains the RF section of a remote control and
Blocking Oscillators were the standard method for creating oscillators and pulses in the Vacuum Tube era. Fast rising/fall times with long pulse repetitions came from a positive feedback topology and from a complex interaction between the pulse-transformer, the grid capacitor, grid resistor and the characteristics of the tube. The
This article describes the development and working principles behind a discrete Spread Spectrum BPSK beacon. The designed system consists of a reference oscillator, frequency multiplier, binary phase-modulator and digital microcontroller, integrated on a single PCB. The presented architecture could easily be implemented in CubeSats or for terrestrial monitoring of distant
Parametric amplifiers and frequency dividers are a class of devices less known by RF enthusiasts. Modulation of some parameter of the circuit, commonly the active gain or the resonant susceptances, enables amplification by energy pumping or sub-harmonic oscillation. In this article, we use parametric sub-harmonic oscillation to create a microwave
In most modulation systems, for transmission over long distances, high power amplifiers are used at the output. Large amplifiers are intrinsically nonlinear, due to their class of operation and the trade-off of linearity vs. efficiency of the design. Nonlinear models are every engineer's nightmare. In the field of
One of the most important factors for understanding the phenomena found in day-to-day engineering is the deep knowledge of the tools and their natural functioning. I mean, by natural, the intrinsic characteristics – the connection the tool has with nature, which appears only when we interconnect knowledge with other areas,
In digital communication, where data messages are transmitted encoded in bitstreams, the receiver end is always presented with the challenge of clock recovery. Clock recovery is the art of reestablishing the time slices of the encoded bits, that were generated in the transmitter side. This timing information, for NRZ signals,
For proper operation of the Microwave Power Meter , a calibration system was developed, working as a dynamic mapping function that converts the Power Meter Probe voltage to the corresponding input power. The calibration system and procedures determines the final absolute accuracy of the equipment, and its design needs to allow