What is "Bootstrapped HF rejection"

Thread Starter


Joined Aug 23, 2021
Can anyone explain this bootstrapped HF rejection which is shown in the below circuit?
What is the purpose of that?
*This is a diagram of an active EEG electrodes
A standard Bootstrap oscillator consists of two rugged OCXOs of the same frequency, which can be any fixed frequency from 10 MHz to 25 MHz, and all the necessary components for the phase synchronization of the two oscillators. To minimize vibration-induced phase noise, special compensation techniques are used, including mechanical positioning of the two oscillators on two axes to compensate for vibration sensitivity, and adjusting the electrical tuning of both oscillators with an appropriately scaled compensation voltage. The Bootstrap Generator Node is the ideal solution for the most demanding aerospace, mobile and marine applications requiring significantly improved dynamic phase noise performance with an effective acceleration sensitivity characteristic close to 2E-11 / g per axis. The effective acceleration sensitivity up to 2E-12 / g can be realized by adding an external vibration isolation system, assuming a typical natural fixture resonance frequency of about ~ 30 Hz. The assembly is housed in a 4.5 x 4.0 x 0.9 inch machined aluminum housing. The internal voltage regulator ensures perfect deflection of the power line.

Delta Prime

Joined Nov 15, 2019
hello there! :) Current to voltage conversion amplifiers or transimpeadence amps are used when high bandwidth and high sensitivity are required when using capacitive sensors like active
Electrodes of a EKG because at high frequencies the total input capacitance can limit the bandwidth of a circuit. Resulting in an unstable dynamic response. So techniques are used to reduce the input capacitance called bootstrapping by using an additional Buffer amplifier to charging & discharge Input capacitors which in turn lowers the input capacitance which in turn raises or increases overall bandwidth.
And a standard bootstrap oscillator does not consist of a two Oven Crystal oscillators!!