Instrumentation Receiver: Analog Signal Processing for a DSP World. Rick Campbell Portland State University

Transcription

1 Instrumentation Receiver: Analog Signal Processing for a DSP World Rick Campbell Portland State University

2 Tonight s Talk discusses 3 questions: What is an Instrumentation Receiver? How does Rick design one? What is it good for?

3 Part 1: What is an Instrumentation Receiver? An Instrumentation Receiver is a general purpose RF-analog front-end that connects between an antenna or microwave downconverter and audio frequency range signal processing electronics. The output signal might be connected to: Digital Storage Oscilloscope Audio Spectrum Analyzer Analog Voltmeter Baseband Digital Signal Processor Headphones Stereo Headphones Audio Power Amplifier Array Processor Wideband Transmogrifier Filter

4 How is it different from a modern wireless receiver? Modern Receiver Design: Meets specs for specific application High Volume Highly manufacturable Lowest Cost Smallest Highly integrated Example: typical microwave radio chip 2 db Noise Figure 2.4 GHz to 2.5 GHz input -10 dbm input third order intercept integrated demodulator--digital output built in a TSMC RF CMOS process specified die area

5 But an Instrumentation Receiver performs some simple math: RF input: si(t) = a(t){cos[2pfot + j(t)]} + noise baseband output: so(t) = ga(t){cos[2pf1t + j(t)]} + more noise where: f0 - f1 = flo g = gain more noise = noise noise figure...and you very specifically have no idea what it will be used for

6 If we knew the application ahead of time, we could minimize current, move many functions into DSP on some other part of the CMOS die, build 100 million parts that only do one thing. But: to foster Innovation, the Bell Labs stockroom in 1975 was full of useful parts, not ASICs: transistors, transformers, diodes, capacitors, resistors, motors, photocells, microphones, switches, batteries, op-amps, mixers, inductors, quartz crystals... These are the basic components creative designers use to do science experiments, test new ideas for next generation technology, and inspire next-generation innovators. We don t know how they will be used when we design them.

7 So my working definition of an Instrumention Receiver is that it is a block in a system: RF in LO in Audio out Instrumentation Receiver It s like a microphone with a built-in preamp, an antenna instead of a pressure transducer, and a frequency conversion inside. The output is identical to a microphone output.

8 My Lab Instrumentation Receiver: Racal RA6790/gm Works great, but too big, too heavy, and too expensive for many applications.

9 My Lab Instrumentation Microphone: Bruel & Kjaer 4006 Works great...too big and expensive for many applications. NASA uses Knowles Acoustics elements on Mars Rover

10 Part 2: How does Rick Design One? pages notebook number 124 Start with pen and paper--not the simulator!

11 Then test the ideas at the bench. Use scale models for mm-wave circuits.

12 Stuff on my bench for measurements: precision attenuators wideband gain blocks narrow filters isolators simple things that I understand Some measurement wisdom: Precision loss is a good thing. Reverse isolation is a very good thing. Amplifiers should be flat and have headroom. Filters should have flat tops and graceful skirts. Connections to the outside world should have well-defined impedance and nothing unsavory leaking out. Measurement tools are both simpler and more refined than commercial products--like a fixed gear bicycle.

13 My specs for an instrumentation receiver: Input S11 < 10 db from 2 to 250 MHz 4.0 db noise figure (makes calculations easy) 60.0 db gain: 1.0 microvolt in = 1.0 millivolt out 2 volt peak-to-peak output into 600 ohms 100 Hz to 20 khz output bandwidth (like microphone) 5% wide Input band anywhere between MHz 40 db adjacent channel interference suppression >>40 db everywhere else little box with SMA RF in, SMA LO in, RCA audio out It connects to anything I would connect a microphone to

14 First: design, build, and measure each subcircuit: Then combine into PC board system: First Pass functional Second Pass meet specs Third Pass limited production run

15 Here s the circuit board--the size of a business card The top half is the RF Signal Processor and the bottom half is the Analog Signal Processor. This one works at 10 MHz RF.

16 Even at 10 MHz using chip components improves RF circuit performance by reducing stray electromagnetic coupling

17 The top half is the RF Signal Processor LNA bandpass amplifier-isolator image-reject mixer I out RF in 15p L1 22 L2 1p L3 22 L4 1p L5 100k 100k 10n 20p 20p 20p 20p n 10n m + m + 10n L6 10n 22p 51 U1 U2 L7 15p 33p L8 LO in 10n 5p Q out 20p Lots of subtle generalizations: A generalization is like an optimization, except it achieves a global, shallow minimum rather than focusing on one parameter.

18 Open-Design: everything is published, no hidden parts

19 The bottom half is the Analog Signal Processor LNA 33u I I in 33u Q 24 LNA 1.5k 24 Q in 1.5k 10u 10u 10k 10k 3.0k 3.0k 3.9k 3.9k k 10u 100k 27k 220n k 10u 100k 27k 220n s1 s k 30.1k 10.0n 10.0n 10.0n all-pass a 10k 220n b 1.87k 11.8k 115k 10.0n 10.0n 10.0n all-pass sum 33u 470 f k u 3.9k 10n line out Many generalizations...

20 flat passband passband phase Frequency Response and Opposite Sideband Suppression

21 50.1 MHz Instrumentation Receiver with VHFs LO

22 50.1 MHz Instrumentation Receiver with VHFs LO

23 Part 3: What is it used for? Most important answer is: use your imagination! But here are some examples to start you thinking nv MHz sine wave

24 Two-tone Third Order products at 50 MHz Tone spacing 72 Hz

25 antenna element instrumentation receiver Local Oscillator antenna element instrumentation receiver antenna element instrumentation receiver Baseband Processor antenna element instrumentation receiver Electromagnetic Sensor Array with Baseband Combiner

26 100 ohm resistor instrumentation receiver Local Oscillator Audio Voltmeter liquid nitrogen Physics-Based Noise Figure Measurements

27 Signal Generator instrumentation receiver instrumentation receiver Local Oscillator Digital Storage Oscilloscope Integrated Vector Network Analyser

28 Modulated signal predistortion instrumentation receiver instrumentation receiver Local Oscillator Compare Cartesian Feedback System

29 instrumentation receiver Local Oscillator Audio Recorder VHF Sonobouy Receiver

30 Audio Recorder instrumentation receiver Local Oscillator Moose Tracking

31 Monopulse Modulated Scatterer Radar IF...but that s the subject of my next talk. Thank you and good evening. These slides will be posted on: ece.pdx.edu/~campbell