Test Technology Resource Center - Technical NotesCentering Pulse Waveform In a settling time measurement, rise/fall time calculation, and tests known as template fitting test, samplers are used to record waveforms. The test signal waveform in such applications is usually a clock signal with 50% duty ratio. You may want to shift this waveform in the unit test period window to a position so you can analyze and parameterize it. This technical note describes how to shift ("center") your waveform to any desired phase.
HVM Receiver Noise Figure Measurements In the last few years, low-noise amplifiers (LNA) have become integrated into receiver devices that bring signals from the antenna to analog or digital baseband domains (I and Q). In doing so, it has become more commonplace to test noise figure in this RF-to-baseband configuration. There are two primary techniques used to perform noise figure measurements on these devices with automated test equipment (ATE); Y-Factor and Cold Noise (or Gain) methods. Differences between making measurements on RF-to-RF devices and RF-to-baseband devices are discussed in this article. Additionally, considerations for HVM (High-Volume Manufacturing) testing of noise figure are presented.
Application Note - Filter Test using Pseudo Swept Frequencies Frequency response is a key test item for filters. To measure the gain-frequency response, phase-frequency response, and group delay for filters, you can use the pseudo swept frequencies method. This method incrementally changes the input signal frequency to a filter (DUT), and measures the output signal from the filter.
Method for calculating SNR for Non-integer Cycle Sine Wave Sine waves are the most fundamental waveform used in analog tests. In the mixed-signal IC testers which use DSP (digital signal
processing), they are used to calculate test parameters such as THD (total harmonic distortion), SNR (signal-to-noise ratio) and frequency characteristics
with FFT (fast Fourier transform). However, if the frequency of the measured sine wave is slightly different from expected frequency, and the number of
cycles of the captured waveform ceases to be an integer, then FFT processing will cause leakage and the measurement accuracy will decline. Read entire
application note.
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Test Technology Resource Center - Technical NotesMixed Signal Lecture Series: DSP-Based Testing Fundamentals 4 Multi-tone is a popular stimulus signal in mixed signal tests. By using a multi-tone you can capture gain and phase information at multiple frequency points with a single measurement so that it is very effective in frequency response analyses. As discussed in the last newsletter, when a multi-tone is programmed and generated by a DAC, it has a gain shaping of SINC function. In this issue, let’s look at the waveform and think of the point of appropriate multi-tone signal generation.
Mixed-signal Lecture Series: DSP-Based Testing Fundamentals 3 When a DA converter (DAC) is stimulated a certain code, the DAC generates a DC voltage specified and holds its level until the next code is fed in the DAC. Therefore the waveform out of a DAC theoretically looks like staircase. In this issue let’s look at the DAC output waveform.
Modulation Fundamentals 2 - Bluetooth EDR Demodulation on the V93000 Although Bluetooth has been around for years and was thought to be mature in the automated test equipment (ATE) world, new test requirements have arisen. In 2005, Bluetooth EDR (Enhanced Data Rate) v2.0 was introduced, adding increased data throughput over first-generation Bluetooth (v1.0 and v1.2). Although it has kept the occupied bandwidth the same, this additional data rate has introduced many new test requirements that need to be explained and understood.
Modulation Fundamentals 1 - Modulation and EVM Analysis
Modulation analysis is increasingly integral to the test strategies of integrated RF SOC transceivers. The trend is that as the industry gets closer to a single-chip cell phone, more and more mission mode tests need to be performed on the transceivers to make sure that all components of the radio are working together flawlessly. In RF SOC, nothing represents mission mode test better than error vector magnitude (EVM). An acceptable EVM measurement for a complex modulation format implies that a whole host of transmitter or receiver components are within specification.
How can I improve my inter-modulation distortion (IMD) results? Inter-modulation distortion occurs when multiple input frequencies (usually two) to a non-linear device cause additional unwanted signals. To improve the test, it is necessary to minimize the effects of the RF source or the RF measurement sub-system.
Why is my SNR result so bad? SNR result of an ADC or DAC is bad. I expected 60dB SNR of 1 MHz signal at 10 MHz bandwidth but it only has 45dB. What is wrong?
