Principles & Applications Electronics Principles & Applications Sixth Edition Charles A. Schuler Chapter 13 Integrated Circuits ©2003 Glencoe/McGraw-Hill

INTRODUCTION IC Fabrication The 555 Timer Analog ICs Mixed-signal ICs Troubleshooting

The base process in making ICs is photolithography. Silicon wafer (the substrate) oxidized on its surface Coated with photoresist Covered with a photomask Exposed to light and developed Etched to expose the substrate Impurity diffusion into the substrate Repeat eight to twenty times

Dopant Silicon substrate Coat with photoresist Expose with light Cover with photomask Develop Start with a silicon substrate Coat with silicon dioxide Etch Diffusion A P-N junction has been formed.

Wafer Batch Processing Each wafer will yield dozens of ICs (or more).

Probe Test

After the wafer is separated, the defective ICs are discarded. During the probe test, the defective ICs are marked. After the wafer is separated, the defective ICs are discarded.

Using photolithography to form an NPN BJT 1. P- type substrate 6. Boron diffusion 2. N+ diffusion layer 7. Silicon dioxide layer 3. N epitaxial layer 8. Expose and etch 4. Silicon dioxide layer 9. Boron base diffusion 5. Expose and etch 10. Emitter diffusion Using photolithography to form an NPN BJT

Using photolithography to form an NPN BJT 11. Coat, expose and etch 12. Aluminum metalization layer 13. Coat, expose and etch away extra aluminum Base contact Collector contact Emitter contact Using photolithography to form an NPN BJT

IC Fabrication Quiz The base process in making monolithic Ics is __________. photolithography The wafer is coated with photoresist and exposed through a __________. photomask Etching produces windows through which impurities are __________. diffused The electrical performance of each chip on the wafer is checked during the __________ test. probe Individual sections are electrically connected with a film of __________. aluminum

555 +VCC 8 Discharge 7 5 kW Threshold 6 2/3 VCC S Q Control 5 kW 3 5 R A popular timer IC Discharge 7 555 5 kW Threshold 6 UTP 2/3 VCC S Q Control 5 kW 3 5 R Q 1/3 VCC Out LTP Trigger 2 5 kW 1 Gnd 4 Reset

Once set, the Q output remains high until the flip-flop is reset. How the RS flip-flop in the 555 timer works: S R Q Q S Q Outputs are in opposite states. R Q Once set, the Q output remains high until the flip-flop is reset.

One-shot Operation +VCC 8 R 7 6 C 3 2 1/3 VCC 1 Discharge transistor R 7 6 C S 3 R output pulse input trigger 2 1/3 VCC 1 The input trigger resets the flip-flop and C then charges until the top comparator trips and sets the flip-flop.

R 8 4 7 C 555 6 3 t = 1.1RC Output pulse 2 Trigger 1 + VCC R 8 4 7 C 555 6 3 t = 1.1RC Output pulse 2 Trigger 1/3 VCC 1 The external components determine the output pulse width.

C charges through RA+ RB and discharges through RB. +VCC C charges through RA+ RB and discharges through RB. 8 Free-running or Astable Operation 7 RB 6 S 3 R 2 C 1 2/3 VCC 1/3 VCC

Astable Mode Duty Cycle > 50% + VCC RA 8 4 7 RB 555 6 3 2 C 1 Duty Cycle = RA + 2RB x 100% RA + RB f = 1.45 (RA + 2RB)C

Astable Mode Duty Cycle < 50% + VCC Astable Mode Duty Cycle < 50% C charges through RA and discharges through RB. RA 8 4 7 RB 555 3 6 2 C 1 RA Duty Cycle = RA + RB x 100% f = 1.45 (RA + RB)C

Time-delay Mode R 8 4 6 555 3 2 1 C Trigger Time delay = 1.1 RC Output + VCC Time-delay Mode R 8 4 6 555 3 2 1 C Trigger Time delay = 1.1 RC Output

Pulse-position Modulation

555 Timer Quiz The voltage of the trigger signal must be less than 1/3 __________. VCC The threshold and trigger comparators control the __________. RS flip-flop The Q output of the RS flip-flop controls the __________ transistor. discharge In one-shot mode, the external R and C set the __________ of the output pulse. width In astable mode, the 555 timer acts as an __________. oscillator

Analog ICs include: Linear voltage regulators Differential amps High-speed amps Op amps RF and IF amps Modulators and mixers Demodulators Power amps

The LM3876 delivers up to 56W of audio output power to an 8 W load. VIN+ VIN- Mute Gnd 11-lead TO220 plastic package 0.1% THD 20 Hz – 20 kHz 95 dB SNR Load, voltage and temperature protected 100 W peak output

Mixed signal ICs contain or use both digital and analog circuit functions. 1 2 3 4 5 6 GND U/D CS W H VCC MAX5468 This Maxim digital potentiometer is an example. It provides 32 output levels from pin 5 for volume control applications. It is adjusted by applying digital pulses to pin 3. Pin 4, along with pin 3, selects either a volume up or a volume down mode.

Phase-locked loops are mixed signal ICs. Error Amplifier Phase Detector LPF VCO The phase detector is usually digital.

Phase-locked Loop In In VCO Phase Error LPF Detector Amplifier VCO The VCO locks onto the input phase. In VCO

The VCO also locks onto the input frequency. Error Amplifier Out In Phase Detector LPF VCO Output voltage Lock range Input frequency

PLLs can serve as FM detectors. Error Amplifier Out In Phase Detector LPF VCO

PLL Frequency Synthesizer Error Amplifier fREF Phase Detector LPF Digital divide by N fOUT = N(fREF) VCO fOUT

A sample and hold can be a separate circuit or part of an analog to digital converter. A/D occurs when signal voltage is not changing switch to A/D hold capacitor analog input clock

4-bit D/A Converter Output states = 2N = 24 = 16 5 V 5 V 8 R R 2R Vout

Switched Capacitor Voltage Inverter 1 ms -10 time volts

Switched Capacitor Voltage Doubler 1 ms 20 time volts

Conventional and Switched Capacitor Integrators Slope of Vout = -Vin x RC 1 R C2 C1 1 ms 10 time volts Slope of Vout = -Vin x C2 C1x fclock

Mixed Signal IC Quiz When a PLL is locked, the VCO tracks the input __________. signal PLLs can be used as FM __________. detectors With a divide by N, a PLL serves as a frequency __________. synthesizer The output of a 6-bit D/A converter has __________ possible output levels. 64 The output slope of a switched capacitor __________ depends on the clock frequency. integrator

Troubleshooting Be sure to take a system point of view. Is there any software involved? Supply voltages may be critical. Waveform analysis is often used. Check clock frequency.

REVIEW IC Fabrication The 555 Timer Analog ICs Mixed-signal ICs Troubleshooting