Oscillators - Signal Generators

Oscillator Circuits

Basic Free-Running Multivibrator

• Circuit diagram includes components: Op-amp, resistors R, R1, and R2, and capacitor C.
• Output voltage is denoted as v_O.
• Negative input voltage is vN and positive input voltage is vP.
• Design equations:
  • Frequency: f_0 = \frac{1}{T}
  • Period: T = 2RC \ln(1 + 2\frac{R1}{R2})

Single Supply Free-Running Multivibrator

• Circuit diagram includes components: Op-amp, resistors R, R1, R2, R3, and R4, and capacitor C.
• Voltage source: V_{CC}.
• Output voltage is denoted as v_O.
• Negative input voltage is v_N.
• Design equations:
  • Frequency: f0 = \frac{1}{RC \ln(\frac{V{TH}}{V{TL}} \times \frac{V{CC} - V{TL}}{V{CC} - V_{TH}})}

Triangular Wave Generators

• Circuit diagram includes components: Op-amp, resistors R, R1, R2, and R3, capacitor C, and voltage source V{SQ}.
• Intermediate voltage is denoted as v_1.
• Threshold voltage is denoted as V_T.
• Design equations:
  • Frequency: f0 = \frac{R2}{R_1} \frac{1}{4RC}

Triangular Wave Generators: Slope Control

• Circuit diagram includes components: Op-amp (OA), comparator (CMP), resistors R, R1, R2, R3, RH, and RL, capacitor C, diodes D1, D2, D3, and D4, and voltage source V{SQ}.
• Intermediate voltage is denoted as v_1.
• Threshold voltage is denoted as V_T.
• Design equations:
  • Low time: TL = 2 \frac{R1}{R2} C(RL + R)
  • High time: TH = 2 \frac{R1}{R2} C(RH + R)

Free-Running Multivibrator Using CMOS Gates

• Circuit diagram includes components: CMOS gates I1 and I2, resistor R, capacitor C, and voltage source V_{DD}.
• Voltages at different points are labeled as V1, V2, and V_3.
• Output voltage is denoted as V_O.
• Condition: 1 >> R
• Design equations:
  • Frequency: f0 = \frac{1}{RC \ln(\frac{V{DD} + VT}{VT} \times \frac{2V{DD} - VT}{V{DD} - VT})}

Monostable Multivibrator

• Circuit diagram includes components: Op-amp (AI), resistor R, capacitor C, and voltage source V_{DD}.
• Input voltages are v1 and v2.
• Output voltage is denoted as V_{out}.
• Design equations:
  • Pulse width: T = RC \ln(\frac{V{DD}}{V{DD} - V_T})

The 555 Timer as an Astable Multivibrator

• Circuit diagram includes a 555 timer IC with connected components: resistors RA and RB, and capacitor C.
• Various pins are labeled: TRIG (2), GND (1), THRESH (6), DISCH (7), VCC (8), RES (4), and OUT (3).
• Output voltage is denoted as V_{OUT}.
• Design equations:
  • Period: T = TL + TH = RB C \ln 2 + (RA + RB) C \ln(\frac{V{CC} - V{TH}/2}{V{CC} - V_{TH}})
  • Frequency: f0 = \frac{1.44}{(RA + 2R_B)C}
  • Duty cycle: D(\%) = 100 \frac{RA + RB}{RA + 2RB}

The 555 as a Monostable Multivibrator

• Circuit diagram includes a 555 timer IC with connected components: resistor R and capacitor C.
• Various pins are labeled: DISCH (7), GND (1), TRIG (2), THRESH (6), VCC (8), RES (4), and OUT (3).
• Input voltage is denoted as v_I.
• Output voltage is denoted as V_{OUT}.
• Design equations:
  • Pulse width: T = RC \ln(\frac{V{CC}}{V{CC} - V_{TH}})

Voltage-Controlled Oscillator

• Circuit diagram includes components: Op-amp (OA), comparator (CMP), resistors R, R1, R2, R3, and 2R, capacitor C, and current source iI.
• Input voltages are vI and v{I2}.
• Threshold voltages are V{TH} and V{TL}.
• Design equations:
  • Frequency: f0 = \frac{vI}{8RC(V{TH} - V{TL})}

Sawtooth Wave Generators

• Circuit diagram includes components: Op-amp (OA), comparator (CMP) LM311, resistors R, R1, R2, R3, capacitor C, C1, and current source i_I.
• Voltage source: +15V
• Input voltages are vI and vP.
• Output voltage is denoted as v_{ST}.
• Output pulse is denoted as v_{PULSE}.
• Design equations:
  • Frequency: f0 = \frac{1}{RCVT / |vI| + TD}
  • Simplified frequency: f0 = \frac{|vI|}{RCV_T}