October 19, 20071

EE 359 Electronic Circuits

Filters and Tuned AmplifiersFilters and Tuned Amplifiers

Second order LCR resonator

Second order Active Filters based on Inductor Replacement

Signal GeneratorsSignal GeneratorsOscillators

October 19, 20072

EE 359 Electronic Circuits

HW

Due today 12.7, 12.9,12.28, 12.34

Review October 26

Quiz#2 October 29

October 19, 20073

EE 359 Electronic Circuits

Second Order LCR Resonator

• LCR Resonator

• Excite parallel LCR resonator– Determine natural

modes (I.e. poles of response function)

LCCRss

CsRsCsLYI

V

/1)/1(

/

/1/1

11

2

0

CRQ

LC

CRQ

LC

0

0

0

20

/1

/1/

/1

October 19, 20074

EE 359 Electronic Circuits

Transmission Zeros LPF

• Where to inject iput signal Vi ?

• Transmission zeros are when Z2(s) are zero (if Z1

)()(

)(

)(

)()(

21

20

sZsZ

sZ

sV

sVsT

i

October 19, 20075

EE 359 Electronic Circuits

Realization of Low Pass Function

• Transmission zeros are when series impedance becomes infinite.

0/1

1

RsCssL

RsCsL

sL

YY

Y

ZZ

Z

V

VsT

i /1/1

/1)(

21

1

21

20

October 19, 20076

EE 359 Electronic Circuits

High Pass Filter

• Use the series capacitor. Transmission zero at s=0 (dc), shunt inductor is a tranmission zero at s=0.

200

2

220

/)(

Qss

sa

V

VsT

i

October 19, 20077

EE 359 Electronic Circuits

Bandpass Filter

• Zero at s=0 due to shunt inductor, s=infinity due to shunt capacitor.

LCCRss

CRs

V

VsT

i /1/1

)/1()(

20

October 19, 20078

EE 359 Electronic Circuits

Inductance Simulation

• Use opamps instead of inductor!

October 19, 20079

EE 359 Electronic Circuits

Low Pass Filter

)()(

)(

)(

)()(

21

20

sZsZ

sZ

sV

sVsT

i

RsCsL

sL

YY

Y

ZZ

Z

V

VsT

i /1/1

/1)(

21

1

21

20

October 19, 200710

EE 359 Electronic Circuits

High Pass Filter

• 200

2

220

/)(

Qss

sa

V

VsT

i

October 19, 200711

EE 359 Electronic Circuits

Bandpass Filter

•

LCCRss

CRs

V

VsT

i /1/1

)/1()(

20

October 19, 200712

EE 359 Electronic Circuits

Low Pass Notch filter

•

October 19, 200713

EE 359 Electronic Circuits

Second-order narrow-band bandpass filter by transforming a first-order low-pass filter. (a) Pole of the first-order filter in the s-plane. (b) Applying the transformation s = p + j0

and adding a complex conjugate pole results in the poles of the second-order bandpass filter. (c) Magnitude response of the firs-order low-pass filter. (d) Magnitude response of the second-order bandpass filter.

Second-order narrow-band bandpass filter by transforming a first-order low-pass filter

October 19, 200714

EE 359 Electronic Circuits

Poles and the frequency response of a fourth-order stagger-tuned narrow-band bandpass amplifier by transforming a second-order low-pass .

October 19, 200715

EE 359 Electronic Circuits

SIGNAL GENERATORS /OSCILLATORS

A positive-feedback loop is formed by an amplifier and a frequency-selective network

In an actual oscillator circuit, no input signal will be present

October 19, 200716

EE 359 Electronic Circuits

Oscillator-frequency stability

October 19, 200717

EE 359 Electronic Circuits

Limiter Ckt Comparator

October 19, 200718

EE 359 Electronic Circuits

Wien-bridge oscillator

without amplitude stabilization.

October 19, 200719

EE 359 Electronic Circuits

Wien bridge w/ Amp. Stabil.

limiter used for amplitude control.

October 19, 200720

EE 359 Electronic Circuits

Alternate Wien bridge stabil.

October 19, 200721

EE 359 Electronic Circuits

Phase Shift Oscillator

October 19, 200722

EE 359 Electronic Circuits

Phase Shift. Osc. W/ Stabil.

October 19, 200723

EE 359 Electronic Circuits

Quad Osc. Circuit

October 19, 200724

EE 359 Electronic Circuits

Active Tuned Osc.

October 19, 200725

EE 359 Electronic Circuits

OPAMP based Tuned Amp. Osc.

October 19, 200726

EE 359 Electronic Circuits

Colpitts and Hartley Oscillators

October 19, 200727

EE 359 Electronic Circuits

Equiv. CktTo simplify the analysis, neglect Cm and rp

Consider Cp to be part of C2, and include ro in R.

October 19, 200728

EE 359 Electronic Circuits

Collpits Oscillator

October 19, 200729

EE 359 Electronic Circuits

Piezzoelectric Crystal

October 19, 200730

EE 359 Electronic Circuits

Pierce Oscillator

CMOS inverter as an amplifier.

October 19, 200731

EE 359 Electronic Circuits

Bistable Operation