Simple? Δf=fc/Q (-3dB BWp)
Q of 3 at fc = 150kHz gives ;
- 3dB @ BWp = 50kHz max (27kHz, 76kHz)
- 6dB @ BWp = 77kHz max ( 123kHz, 200kHz )
- 12dB @ BWp = 193kHz max (82kHz, 275kHz )
(using a model for linear phase Multiple Feedback 0.05 deg; )
so maybe Q=3.1
So what's all this Stuff About Filter Specs and tolerance error?
Maybe you want a flatter passband and and a steeper stopband?
Then a Chebychev BPF staggers higher Q poles to make the ripple small e.g. 0.1, 0.5 or 1dB in the PassBand and thus higher Q yields steeper skirts in the StopBand.
Maybe you want linear phase or maximally flat Group Delay?
Like Bessel filters then using lowest Q staggered poles in the PB it minimizes excessive group delay in the pass band.
Or maybe some other characteristic such as phase shift sensitivity or maybe stability with tolerance using 0.5% tolerance stackup or 5% tolerance parts..
So the usual specs to define any simple filter as follows;
- Gain (Ao):
- Center Frequency (fo):
- Allowable Passband Ripple (Rp): [dB]
- Passband Bandwidth (BWp @ -3 dB):
- Stopband Bandwidth (BWs @ -Asb dB):
- Stopband Attenuation (Asb):
- Filter Order (optional): with -6dB*n per octave slope
More complex filters are defined by scattering paramters for input and output impedance s11,s22 and transfer function s21.