KI4: SIGNAL TRANSMISSION IN A RADIO SYSTEM

Transcription

1 KI4: SIGNAL TRANSMISSION IN A RADIO SYSTEM

2 DETAILED TRANSMISSION CHANNEL IN A RADIO SYSTEM Pre-amp (33) Carrier frequency in radio systems (31) Modulation techniques (up conversion) (31) CMOS drivers for power amplifiers in radio transmission path (33) Band-pass filters (BPF) and their transfer function in the Laplacian domain (31) Passive vs. active BPFs (33/31) RF power amplifiers and its efficiency illustrated as a CMOS driver plus a BPF (33/34) Antennas and radiation in radio systems (34) Antenna size as a function of carrier frequency (34)

3 A DEMO SYSTEM SILICON LAB SINGLE CHIP TRANSMITTER

4 QUESTIONS 1.Can you transmit a low-frequency signal (e.g. voice signal) directly over the air?. How do you transmit a low-frequency signal over the air efficiently? 3. What operations do you use in a radio transmitter to achieve the goal of sending a low-frequency signal over the air? 4. Can you draw the spectrum diagram before and after the operation?

5 QUESTIONS 5. What are the important characteristics of the baseband amplifier for low-frequency signals before they are put on a carrier frequency? 6. Why do we need BPFs? What do they do? What are some of the important characteristics of the BPFs? How can they be implemented?

6 QUESTIONS 7. What are different antenna configurations? What different radiation patterns do they generate? 8. Dipole antenna is common. Describe its operating principles 9. Can you describe how a low-frequency signal is transformed along a transmission circuit in a radio system?

7 ANTENNA

8 DIPOLE ANTENNA RADIATION PATTERN

9 LOCAL OSCILATOR Ideal LC Tank 1 0 LC 0 Q 1 L LC 1 1 0L1 R RC L 1 Real LC Tank

10 LOCAL OSCILATOR Tuning is provided by the programmable capacitor Tuning range: 90MHz 98MHz Able to compensate for 5% process variation Able to compensate for % inductance variation L = 17nH, Q = 30 Output swing 1Vp-p Ibias = uA

11 0 v V cos t LO signal, o o o V is set not to put the FET MIXER USING SQUARE LAW k' W Square Law : I D Vgs Vt 1 Vds L k' W V Q V o cos 0 t V t 1 V ds L V V cos t V V V V or V V V Q o 0 t Q o t o Q t Expand the square term : in cutoff cos 0 cos 0 I V V V t V V V t D Q t o Q t o

12 The DC current from the previous equation: ' I k W V V V L cos t 1 D, DC Q t ds MIXER USING SQUARE LAW Further expand the term: 0 1 cos 0t cos0tcos0t 1 cos0t k' W I D VQ Vt Vo cos 0t VQ Vt Vo cos 0t L k' W I D, DC Vo cos 0t VQ Vt Vo cos 0t L W Vo V o I D, DC k ' VQ Vt Vo cos0t cos0t L 4 4 bias point shift LO modulation nd -order harmonics. ignore

13 ACTIVE LOW-PASS FILTERS

14 ACTIVE HIGH-PASS FILTERS

15 ACTIVE BAND-PASS FILTERS

16 Video Presentation for Knowledge Integration 4 Spring 017 (Due Feb. 17, 017) Video presentation is a part of the KI exercise where you use the KI4 content you learned to make a short 7-minute video online. The details of KI4 content is given in the separate pre-work assignment. The video presentation should include the following: 1. Introduction of the signal transmission circuit of a radio system.. Specific key concepts in each of the junior year courses (ECE31, ECE33, and ECE34) that are used in building the transmission circuit in a radio system. 3. A summary of how specific key concepts are integrated in building a transmission circuit in a radio system. You will record the video presentation at your own time using a web tool called YOUSEEU. Attached you can find two documents providing specific instructions about how to run YOUSEEU on your computer. Your computer needs to have a web camera and a microphone in order to run YOUSEEU. You can sync a set of slides with your video recording after the recording is done if you prefer. You must upload the final version of the presentation no later than 5pm on /17 (Friday). You video presentation will be judged by a small group of your peer students using a scoring rubric. A few tips for making the video presentation: 1. Introduce yourself first.. Look into the camera when you speak. 3. Speak clearly and avoid using complex sentences and phrases. 4. Accompanying slides can help you make your point, but keep the slides simple and easy to read. 5. Be concise and don t get into too much detail, and keep it within the 7 minute time limit.

17 CATEGORY Excellent-3 Good- Needs Improvement-1 Score Sequencing of There is no clear plan for the organization of Information information. Information is organized in a clear, logical way. It is easy to anticipate the next slide. Most information is organized in a clear, logical way. An occasional slide or piece of information seems out of place. Effectiveness Use of Graphics Presentation includes all material needed to give a good understanding of the topic, including a clear introduction. The presentation is consistent with the driving question. All graphics are attractive (size and colors) and support the topic of the presentation. Presentation is lacking one or two key elements. Presentation is inconsistent with driving question some of the time. A few graphics are either not attractive or do not support the topic of the presentation. Presentation is lacking several key elements and has inaccuracies. Presentation is completely inconsistent with driving question. Several graphics are unattractive AND detract from the content of the presentation. Text - Font Choice & Formatting Font formats (color, bold, italic) have been carefully planned to enhance readability and content. Font formatting has been carefully planned to complement the content. It may be a little hard to read. Font formatting makes it very difficult to read the material. Spelling and Grammar Presentation has no misspellings or grammatical errors. Presentation has 1- misspellings and/or grammatical errors. Presentation has more than grammatical and/or spelling errors. Delivery Presenters spoke at a good rate, volume and with good grammar. They maintained eye contact while using, but not reading, their notes. Presenters spoke at a good rate and volume, but sometimes used poor grammar. They relied heavily on their notes and did always maintain good eye contact.. Presenters demonstrated having paid little attention to rate, volume or grammar. They read nearly word for word from notes. Technical Content Accuracy All content throughout the presentation is accurate. There are no factual errors. The content is generally accurate, but one or more pieces of information is clearly inaccurate. The content is confusing or contains more than one factual error. Technical Content Depth The material presented is sufficiently detailed to enable full understanding of the technical problem and the challenges in solving it. The material presented is almost sufficiently detailed to enable full understanding of the technical problem and challenges in solving it. Only 1- areas were not described in sufficient detail. Audience members were unable to appreciate the technical problems due to the limited detail presented. Technical Content Integration The material presented clearly indicated the integration of content across multiple courses, and the results clearly illustrated this integration. Integration of content was mentioned but was missing some technical detail. The material presented made no mention of the integration of content across multiple course.