I was recently presented with the problem of comparing the noise of two alternative designs that were presented to me. Normally that wouldn’t take much sorting out – a few minutes with a SPICE simulator and you would have the answer. That depends on having reliable SPICE models. The first thing I do when embarking […]
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How to use charge amplifiers
A charge amplifier is not the most common type of amplifier, but very useful in the right circumstances, it is really a current integrator which produces a voltage output proportional to the integrated value of the input current. This is useful when the sensor is capacitive such as a piezo device which could be a […]
Level shifting digital logic signals
In the past digital systems were 5V and analog ones +/-15V or +/-12V. Nowadays analog systems are more likely to be single supply 5V, 3.3V or lower and digital circuitry is likely to be 3.3V, 2.5V, 1.8V, 1.2V or something in between. You might also have LVDS, DDR or other differential or single ended standards […]
How to reduce noise in an electrical circuit
“Noise” can mean different things to different people. In general it is associated with something unwanted. It could be acoustic noise – background noise. In electronic terms it will generally be an unwanted electrical signal. That may be random or systematic. Either way, it would be a nuisance if the level is high enough to […]
How not to design analog filters
I thought I would share some of the crimes against filters that I have seen people commit over the years. 2+2=4? So, you have designed a 2 pole Butterworth filter for example and want a 4 pole one so you put two of them together. You have a four pole filter? Yes, but not a […]
Using LTspice for power supply design
Simulation using a SPICE simulator (Simulation Program with Integrated Circuit Emphasis) is handy for checking out designs before building them as well as helping to understand designs and circuit problems. You can experiment without blowing anything up! LTspice from Linear Technology is particularly useful as it is free and available to download from their web […]
LTC6990/1/2/3/4/5 TimerBlox
By Chris Francis I have used various programmable clock generator chips, such as the PLL based devices from IDT for generating high frequency clocks in mixed signal systems, such as pixel clocks for analog to digital converters in video systems. In those applications precision frequencies can be important and speed can be more than 100MHz. […]
5 ways to generate a sine wave
It is not uncommon to need a sine wave but how do you generate it? The “best” or most appropriate method for a particular application depends on several things such as: frequency, purity required, amplitude, possible synchronization with another frequency, variable frequency and/or amplitude. At lower frequencies a Wien bridge might be considered – for […]
