Multi-gigahertz Signal Research Articles

Compressive samplers for RF environments

Compressive sensing offers an alternative to Nyquist sampling in applications where taking a complete set of measurements is impractical due to either length of time required or the volume of data produced. Here we focus on applying compressive sensing theory to RF signal environments (which will be referred to as the "signal"). For multi-gigahertz bandwidth signals, using Nyquist sampling requires billions of samples per second resulting in data rates of tens of billions of bits per second. This is the cost of being able to capture any arbitrary signal. Compressive sensing exploits the fact that man-made signals are structured and non-arbitrary to greatly reduce the number of samples required for signal capture. The compressibility of a signal is measured by its sparsity, which can be thought of as the number of parameters needed to describe the signal. Compressive sensing can reduce sample rate by more than an order of magnitude.

A Clock-Less Jitter Spectral Analysis Technique

In this paper, we propose a method for extracting the spectral information of a multigigahertz jittery signal without using an ideal reference clock. This method utilizes existing on-chip single-shot period measurement techniques to measure single periods of a multigigahertz signal for analysis. Utilizing the same sampling and measuring principle, we propose another less computationally intensive method, based on the derivative principle, to extract only the random jitter component of the signal. To perform analysis on higher frequency signals, both methods are extended to measures multiple signal periods, instead of a single period, at each sampling. These methods do not require an ideal sampling clock, nor any additional measurement beyond existing techniques. Experimental results based on simulation show that these methods can accurately estimate the sinusoidal and random jitters of a multigigahertz signal. Extracted values can be used for estimating the bit-error rate of serial communication systems.

A novel high-impedence probe for multi-gigahertz signal measurement

This paper describes a novel high-impedance hand-held probe based on electro-optic sampling (EOS) for multi-GHz signal measurement of on-board circuits. The probe head and detection optics are assembled into a compact probe module. The probe head consists of a metal needle tip and an EO material. The top of the needle is bonded to the EO material. When the needle makes contact with the signal line of a circuit under test, the signals are measured by detecting the polarization change of laser pulses that propagate through the EO material. The effective 3-dB down bandwidth of the EOS high-impedance probe is 10 GHz. The voltage sensitivity is 0.5 mV//spl radic/Hz. The input resistance and capacitance are >100 M/spl Omega/ and <0.2 pF, respectively. The probe head is very durable and is not susceptible to electrostatic discharge. The probe has been successfully applied to measure multi-GHz signals of on-board communication IC's.

Optical phaselock receiver with multigigahertz signal bandwidth

We have built a balanced pin FET receiver which employs two signal amplification paths for homodyne detection of multigigabit-per-second, pilot-carrier PSK optical signals. Using narrow-line 1.51µm semiconductor lasers, we have employed this receiver to phaselock a local oscillator to a 295 pW pilot carrier with 8° RMS phase error.