Category: Analog Professional

Introduction The impulse invariant transform (IIT) is a method of taking a continuous-time system H(s) and converting it to a discrete-time system. There are multiple ways of doing this, but the IIT does so with the constraint that the impulse response of the discrete-time system is a sampled version of the impulse response of the […]

Introduction I had been working on a pulse-width-modulation (PWM) design. It was a pseudo-digital implementation, in that the output was clocked by a high-speed clock. The actual switching rate was much lower than this clock. I wanted to simulate this design in Cadence/Spectre by running a transient and then taking an FFT. However, I ran […]

I’ve posted a guest article at Circuit Sage, detailing the derivation of a “Viterbi” over-sampling data converter. I’m quite proud of this one. Go over and check it out.movie Mechanic: Resurrection 2016 streaming FYI: this is also the reason I didn’t post directly to this site this week. I try to do a post per […]

In my prior post, I discussed the use of “chopping” (or pre- and post-mixing) to improve the IM2 of RF/analog circuits. New readers should go back and read that post in order to understand the nomenclature and variable names in this post. Lately, I’ve been considering whether any similar (but different) technique can be used […]

Answers question in I/Q Noise figure, and on how to do stability in Cadence ADE.

IM2 Consider the fully differential amplifier shown below:

I wanted to go through a bit of illustration with regard to minimizing MOS diffusion parasitics. I will start with the basics of detailing the MOS semiconductor structure. From there, I’ll display some layout configurations that minimize MOS diffusion capacitance.

In a previous post, I discussed the trade-offs in linearity of several continuous-time sigma-delta schemes. In this post, I will describe a method that linearizes the sigma-delta noise-shaping filter (NSF). That is, the scheme presented in this article greatly suppresses the linearity requirements on the noise-shaping filter. This method applies to both discrete-time and continuous-time […]