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Now that look interesting, I'll try that circuit, looks like it can be implemented with FPGA, without any transistors.
Right now I'm using a comparator with LVDS output to convert sine wave to square, works just fine but consumes too much power.
Unfortunalely, I don't have access to any core...
The differential output is not a problem, I'm using LVDS input, it's actually meant for differential signals. The problem is that a differential oscillator uses two equal capacitors (C1 and C2) and if I replace one with my probe, it will ruin the balance and cause huge harmonics at the output...
I have trimpots instead of actual resistors, I adjusted them for maximum swing.
Lampkin topology is basically like Hartley but with an additional inductor for better LC tank decoupling.
Cprobe is 6-18 pF.
Here are the waveforms.
Distortions.. well, the output will be fed into the FPGA LVDS input...
Hrm. And what about Colpitts sensitivity compared to Lampkin topology?
UPD: I did as you say, removed Q2 and other stuff and I got only 450 mV output.
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I'm also getting increased swing when I remove L1 but sensitivity suffers significantly. I can reduce coupling capacitors...
Power efficient oscillator topologies?
I'm building an oscillator for a battery powered capacitive proximity sensor and I need it to have a high swing (>800 mV) at the output while keeping power consumption low enough. Also it has to have large tuning range, a high ΔF/ΔC ratio and one side of...
So I want to buy a spectrum analyzer and I'm going to measure frequency responses up to 150 MHz with it. However, there's an odd situation: analyzer with a tracking generator costs $2500 and the analyzer without one costs $500 and I'm trying to figure out what would be a better option, buying an...
I need to build a low power, low phase noise 40-60 MHz VCO for an IF stage of RF receiever. The VCO is powered from 3.3V and must drive an SPDT switch IC (KISS mixer), so the output has to be fairly symmetrical. Right now I'm using a simple Clapp oscillator followed by a Schmitt trigger, it does...
All converters I found don't have sufficient resolution or/and sampling frequency.
I've searched a lot and I haven't found anything more suitable than XOR gate, can you please advise some good phase detector ICs?
Great advises, I'll try that.
I mean, PWM amplitude. If it's high enough then...
I'd go too as if the signal amplitude was high enough.
Right, and raising PWM amplitude increases not only the DC value but also the AC part, isn't it? And with much lower added noise.
The signal is coming from a sensor as a phase difference between two square waves and I'm using a XOR gate...
Frequency range is 70-1400 Hz, target SNR is at least 80 dB, higher is better. I use MCP6401 op amp for active filtering, it has 28 nV/√Hz noise density, total filter noise over specified bandwidth is 3.9 μV, filter gain is 2.
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