A glance at the circuit design of the hottest peak

2022-08-16
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A glimpse of peak detector circuit design

recently, I received an email from a student who wanted to design a circuit to detect the peak of 10MHz analog signal. His plan is to use an a/d converter to sample at a Nyquist frequency much higher than 20msamples/second, and then send the subsequent converter output to a high-speed processor running a high priority compact software cycle without accepting interrupt requests. In short, his method is not only expensive, but also there is often an unspeakable smell in the village. The power consumption and space occupation are quite large

although I am hesitant to provide him with free design reference, the recipients of electronic experimental machines that provide all kinds of equipment information at the same time with a verification force of less than 5kn will ignore the free suggestions. But after hesitation, I still give an alternative, that is, a classic analog peak detector. A fast and accurate operational amplifier, several low leakage diodes and a low leakage capacitor can form the core of an excellent peak detector circuit, and its cost is only about $5. The circuit is low power consumption, small size, high speed, cheap, reliable and easy to test. In short, this method is simply unbearable

unfortunately, this student, the future electronic engineer, has no 5 The belt on the force measuring piston falls off or is too loose (so that the piston cannot run at a uniform speed). Understand the concept of a peak detector based on the simulation method. This is not because he is not familiar with the specific details of the circuit, but because his mind is full of how to convert the signal into digital format for accurate calculation. The idea of analyzing and calculating signals in the field of simulation is strange to him; As many people say, for this student, "there is no computing in the simulation field"

this situation is simply too bad. Because for many signal processing needs, simulation is better and often the only way to success. If you need a log amplifier or an RMS-DC converter for linear power supply or RF signal, you must consider the analog method. Maybe you have no choice

in the era when processors "dominate" the entire design field, the peak detector layout I mentioned is very common in analog circuits. For example, the opa111 operational amplifier produced by burr Brown company (now acquired by Ti) lists such a possible circuit in its data book. I think it is a single-chip version of the old multi chip burr Brown device

but things often have two sides. Today's operational amplifiers have superior performance and are cheaper than previous ones. Engineers can use them to achieve truly high-precision, high-speed and cheaper peak detectors. (end)

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