opamp

The inspiration for this series of articles came from Microchip’s TB3103 and TB3104 , which outlined the implementation of current mode controlled buck and boost converters using the PIC16F753’s internal analog peripherals, which include an operational amplifier, a comparator, PWM, etc. As a hobbyist, I’ve always found stuff like transfer functions, bode plots (the more complex ones), and SPICE to be really intimidating. I am aware of what these are, and why they are used in circuit design, but I’ve never really sat down and worked with them before, much less explore their nitty gritty details....

With the addition of these 3 components, I had a fully functional boost converter! However, it is not without its (huge) caveats, and let’s just say that along the way, Murphy has paid me many, many visits. In Chapter 1 , we talked about the sawtooth generator, which connects directly to the an opamp responsible for generating a PWM gate drive signal. So, I thought it made sense to take a closer look at that next....

Being on a little analog synth nerd-out lately, I chose to kick things off by designing the sawtooth generator that will ultimately determine the switching frequency of the boost converter. The sawtooth wave generated is used to derive the PWM signal that drives the gate of the FET. By connecting it and a control voltage to a comparator, a PWM signal with a duty cycle directly proportional to the control voltage will be generated....