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12 Threads found on Bias Startup Circuit
When change dynamically the bias of the oscillator, the frequency stability and phase noise are affected, due to changing the impedances seen by the resonator. Harmonics also (by definition) would be affected by these variations. When is about a good oscillator design (including harmonic generators) I would let the circuit operate in a stable (...)
It is not about the actual power cost, but what supplying some amount of quiescent power demands of other things. Such as, a circuit that draws a lot of startup current, or (worse) has a startup current "hump" somewhere between zero and spec-VIN for the startup current value, may not be bootable with a current limited (...)
Make sure your start up circuit actually does its job correctly (e.g. using a slow start up ramp for VDD): as there's no control for the startup circuit, it could be possible that M5 stays always off (and so doesn't work as startup). Hi erikl this circuit is commonly used e.g. see Baker's CMOS book; there are on
Pls copy the bias needed to be started anc compare it with the original current bias to generate start-up signal.
The second circuit oscillates at 50hz during startup because the bias for the BF422 is bouncing up and down because the output transistor is causing it to jump up and down. it is positive feedback. So RC filter the bias for the BF422 transistor.
Hi all, Pmos M2 is on and work at the deep triode region, so the gate voltage of M3 is equal to VDD, M3 is OFF. how to
You just need to bias for the core of bandgap then using either Vbg compare with a VT or the current which generate by delta Vbe/R compare with an other current to finish start up. Thus either Vbg>VT or delta Vbe>I then you can release start up circuit. Best
Self-biased takes time to charge up internal nodes for correction operation. Initially, there might be incorrect output for the first several cycles. If your purpose is a imprecise comparation or amplification, you may use this circuit. If not, then pls don't use such circuits. To answer your question, the bias will kick (...)
Attached is a bias circuit, would like to discuss what the function of Q176 and Q174. In my opinion, when CD(chip disable) level is high, Vref is set to zero, and then Q172 and Q178 are cut off, so Q176 and Q174 and R85 form a Wildar current souce and supply current to Q170, so as to make sure Vref is set to zero. Would like to know your opinio
If you don't mind a momentary startup glitch, you could use a DC blocking capacitor, and bias the right side to 2.4v with resistors.
if the circuit is self-biased it contains a zero solution. let's say your circuit uses an amplifier or level shift stage. if this current is set by the bandgap then the bandgap has to be running for that current to exist. also, that current must exist to allow the bandgap to run. this would be one instance of a zero solution.. no current (...)
If the A or B is used as bias for gate of PTAT current, i think the circuit will not work. Generally , the statup circuit generates the current for core circuit, once the core circuit work normally , the startup circuit is isolated from the core circuit. (...)