High-Speed Photodiodes in Standard CMOS Technology

High-speed Photodiodes in Standard CMOS Technology describes high-speed photodiodes in standard CMOS technology which allow monolithic integration of optical receivers for short-haul communication. For short haul communication the cost aspect is important , and therefore it is desirable that the optical receiver can be integrated in the same CMOS technology as the rest of the system. If this is possible then ultimately a singe-chip system including optical inputs becomes feasible, eliminating EMC and crosstalk problems, while data rate can be extremely high.

The problem of photodiodes in standard CMOS technology it that they have very limited bandwidth, allowing data rates up to only 50Mbit per second. High-speed Photodiodes in Standard CMOS Technology first analyzes the photodiode behaviour and compares existing solutions to enhance the speed. After this, the book introduces a new and robust electronic equalizer technique that makes data rates of 3Gb/s possible, without changing the manufacturing technology. The application of this technique can be found in short haul fibre communication, optical printed circuit boards, but also photodiodes for laser disks.

1 Introduction

1.1 Outline

2 Short range optical interconnection

2.1 Why optical interconnection?

2.1.1 Electrical and Optical Interconnection - Similarities

2.1.2 Electrical and Optical Interconnection - Differences

2.2 Characteristics of light

2.3 Optical fiber types

2.3.1 Single-mode fibers

2.3.2 Multimode fibers

2.3.3 Plastic optical fibers

2.4 High intensity light sources

2.4.1 Lasers

2.4.2 Light Emitting Diodes (LEDs)

2.5 Photodetectors - introduction

2.5.1 Ideal photodetector

2.5.2 Absorption of light in silicon

2.6 High-speed optical receivers in CMOS for [small lambda] = 850 nm-literature overview

2.6.1 Using standard CMOS technology

2.6.2 CMOS technology modi.cation

3 CMOS photodiodes for [small lambda] = 850 nm

3.1 Introduction

3.2 Bandwidth of photodiodes in CMOS

3.2.1 Intrinsic (physical) bandwidth

3.2.2 Comparison between simulations and measurements

3.2.3 N+/p-substrate diode

3.2.4 P+/nwell/p-substrate photodiode with low

-resistance substrate in adjoined-well technology

3.3 Intrinsic (physical) photodiode bandwidth

3.4 Extrinsic (electrical) photodiode bandwidth

3.5 Noise in photodiodes

3.6 Summary and conclusions

4 High data-rates with CMOS photodiodes

4.1 Introduction

4.2 Transimpedance amplifier design

4.2.1 Transimpedance ampli.ers and extrinsic bandwidth

4.2.2 Impact of noise: BER

4.2.3 Noise of the TIA

4.3 Photodiode selection

4.4 Equalizer design

4.5 Robustness on spread and temperature

4.6 Experimental results

4.6.1 Circuit details and measurement setup

4.6.2 Optical receiver performance without equalizer

4.6.3 Optical receiver performance with equalizer

4.6.4 Robustness of the pre-amplifier: component spread

4.6.5 Robustness of the pre-amplifier: diode spread

4.7 Conclusions

5 Bulk CMOS photodiodes for [small lambda]= 400 nm

5.1 Introduction

5.2 Finger nwell/p-substrate diode in adjoined-well technology

5.3 Finger n+/nwell/p-substrate diode

5.3.1 Time domain measurements

5.4 Finger n+/p-substrate photodiode in separate-well technology

5.5 Finger p+/nwell/p-substrate in adjoined-well technology

5.5.1 Time domain measurements

5.6 p+/nwell photodiode

5.7 Conclusion

6 Polysilicon photodiode

6.1 High-speed lateral polydiode

6.1.1 Pulse response of the poly photodiode

6.1.2 Di.usion current outside the depletion region

6.1.3 Frequency characterization of the polysilicon photodiode

6.2 Noise in polysilicon photodiodes

6.2.1 Dark leakage current in the polysilicon diode

6.3 Time domain measurements

6.4 Quantum efficiency and sensitivity

6.5 Conclusion

7 CMOS photodiodes: generalized

7.1 Introduction

7.2 Generalization of CMOS photodiodes

7.3 Device layer - photocurrent amplitude

7.3.1 Device layer - photocurrent bandwidth

7.3.2 Substrate current-photocurrent amplitude

7.3.3 Substrate current-photocurrent bandwidth

7.3.4 Depletion region current

7.3.5 Depletion region - photocurrent bandwidth

7.3.6 Total photocurrent

7.4 Analog equalization

7.5 Summary and Conclusions

8 Conclusions

8.1 Conclusions