Bi-quad, Filter Machine. - cs.huji.ac.il · Biquad Configurations. C1*C2*S^2-----C1*C2* s^2 +...
Transcript of Bi-quad, Filter Machine. - cs.huji.ac.il · Biquad Configurations. C1*C2*S^2-----C1*C2* s^2 +...
Bi-quad, Filter Machine.
Yuval TaubYuval Millo
Ranon LadnauDotan Ziv
Moshe RodenTomer Zaidenshtein
Biquad scheme
Biquad Configurations.
C1*C2*S^2-------------------------------------
C1*C2* s^2 + gm*C1* s + gm^2
Vin = V3V1,V2 = gnd
High Pass
C1*C2*s^2 + gm^2-------------------------------------
C1*C2* s^2 + gm*C1* s + gm^2
Vin = V1 = V3V2 = gnd
Band Reject
C1*gm*s-------------------------------------
C1*C2* s^2 + gm*C1* s + gm^2
Vin = V2V1,V3 = gnd
Band Pass
gm^2-------------------------------------
C1*C2* s^2 + gm*C1* s + gm^2
Vin = V1V2,V3 = gnd
Low Pass
Transfer FunctionInput ConditionsFilter Type
Stability – Impulse Response
Low pass
Band rejectHigh Pass
Band Pass
Transconductance Amplifier,Used in the Biquad implementation
Voltage Divider
OpAmp specs.
CMRR 34.5 dBCMR 1.3V – 3.25Vgm – 9.42u [1/Ohm]Operating Point – 2.3VVdiffmax – 1VVbias – 5VSlew rate – 24.3(V/uSec)Gain – ~10
CMRR & CMR
V1 rampV2 same ramp + sin
1.3V
3.25V
VDiff-Max – 1.0V
@ 1.5V - reaches saturation
Biquad
Low Pass Filter.Behavioral(matlab) Vs Analog (spice)
21.88Mhz3dB point
High Pass Filter.Behavioral(matlab) Vs Analog (spice)
26.67Mhz3dB point
Band Pass Filter.Behavioral(matlab) Vs Analog (spice)
41.88Mhz3dB point
12.8Mhz3dB point
Band Reject Filter.Behavioral(matlab) Vs Analog (spice)
Band Pass Filter.Time – FFT Example
Input : 3 sinusoids at various
harmonies : 1 Mhz , 30 Mhz &150 Mhz.- Band pass is around
the 12 – 40 Mhzpeak .
Band Pass Filter.Time – FFT Example – I/O & FFTs
Band Pass Filter.Time – FFT Example – Input & FFT
Band Pass Filter.Time – FFT Example – Output & FFT
Band Reject Filter.Time – FFT Example
Input : 3 sinusoids at various
harmonies : 2 Mhz , 10 Mhz &50 Mhz.- Band Reject is
between 7 – 12 Mhz
Band Reject Filter.Time – FFT Example – Analog & FFTs
Band Reject Filter.Time – FFT Example – I/O FFTs
Changing Capacitors –to influence Band Width (LP)
Capacitors increase from 0.25pf to 1pf3db point decreases from around 21 – 48(Mhz) to around 7.3 – 12(Mhz)(spice vs. matlab accordingly)-> about 66% spice & 75% matlab reduction !
Changing Capacitors – cont.
LP transfer function is :Gm^2
-------------------------------------C1*C2* s^2 + Gm*C1* s + Gm^2
2nd order Pole @ gm/(c1c2)1/2
With capacitors at 0.25pf Pole @ 3.76 * 10^7
With capacitors at 1pf Pole @ 9.42 * 10^6
Zero-Pole map & Bode Mag.with 0.25pf capacitors
Zero-Pole map & Bode Mag.with 1pf capacitors
Spice results with 1pf capacitors
Parasitic capacitanceinfluences Band Widthof spice moderesults