超寬帶接收機外文翻譯--超寬頻采樣降頻轉(zhuǎn)換器與抽樣相位偵測器（英文）

1、Ultra-Wideband Sampling Down Converter With Sampling Phase Detector Alexander Reisenzahn, Student Member, IEEE, Stefan Matzinger, Thomas Buchegger, Student Member, IEEE, Sebastian Hantscher, Christian G. Diskus, Senio

2、r Member, IEEE A. Reisenzahn, S. Matzinger, S. Hantscher, C. G. Diskus are with the Institute for Microelectronics at the Johannes Kepler University, Altenberger-Strasse 69, Linz, 4040, Austria, email: alexander.reisen

3、zahn@jku.at T. Buchegger is with the Linz Center of Competence in Mechatronics, Altenberger-Strasse 69, Linz, 4040, Austria. Abstract- Ultra-wideband radar is an excellent tool for nondestructive examination of walls

4、and highway structures. Therefore often steep edged narrow pulses with rise-, fall-times in the range of 100 ps are used. For digitizing of the reflected pulses a down conversion has to be accomplished. A new low cost

5、 sampling down converter with a sampling phase detector for use in ultra-wideband radar applications is presented. Key Words- Ultra-Wideband, Sampling Phase Detector, Sampling Down Converter, Sampling Circuit I. INT

6、RODUCTION Ultra-wideband (UWB) pulses are very attractive for radar applications. Advantages are a higher range measurement accuracy and range solution due to the short pulse duration, immunity to passive interferers

7、and many others. The spectrum starts at very low frequencies and extends to very high frequencies. The Federal Communications Commission (FCC) allocates a frequency range of 7.5 GHz from 3.1 GHz up to 10.6 GHz for un

8、licensed use in communication or radar applications and from 2 GHz to 10.6 GHz for through wall imaging [1]. The form of the reflected pulse yields the target information. To enable an interpretation of the signal an

9、 analog to digital conversion is necessary. Today a direct conversion of pulses in the subnanosecond region is impossible. Therefore a sampling down converter is necessary, which is used for example in sampling oscill

10、oscopes and radar applications. The discussed sampling down converter should be useful for low cost UWB radar applications like detecting hidden inclusions in walls. The function principle of a sampling down converte

11、r is explained in the following. Pulses with a pulse repetition time tPR are sent by a transmitter. Fig. 1 shows the reflected pulses. These pulses have a duration tPL of some hundred picoseconds. The sampler has to

12、be turned on after a little longer time than the pulse repetition time tPR. This can be accomplished for example with a slightly higher frequency (fPR = 30 MHz, fSample = 30.000001MHz) or the sampling clock is phase

13、shifted with a direct digital synthesizer (DDS). At each reflected pulse a sample is taken, marked by the dots. The accumulated samples form the down converted pulses. timeamplitudetPRtPLtSampleFigure 1. Principle of s

14、ampling down conversion. II. SAMPLING PHASE DETECTOR In previous publications [2], [3] the sampling down converter has been built of discrete elements. In the presented circuitry the sampling phase detector (SPD) conta

15、ins all necessary parts in one package. Up to now SPDs have been used for the phase lock of a voltage controlled oscillator in the VHF, UHF and microwave range in communication and radar application [4], [5] and for

16、 synchronization in pulse based UWB transmission systems [6]. A SPD consists of a step recovery diode (SRD), two capacitors and a series pair of Schottky diodes as shown in Fig. 2. SPD LO-IN RF-INIF-OUTFigure 2. Circu

17、itry of the sampling phase detector. The SRD is a special diode with an extremely fast recovery time in the range of picoseconds. Charge is stored during the positive half from a sinusoidal signal and extracted during

18、the negative half cycle to generate a current pulse with a rise time equivalent to the recovery time. Therefore the SRD generates step functions of a differential sinusoidal LO-input signal which are differentiated t

19、o pulses 0-7803-9433-X/05/$20.00 ©2005 IEEE. APMC2005 Proceedings Figure 5. Down converted UWB radar pulse. The pulse shape agrees much better with the original pulse if a DDS is used for phase-shift. The result i

20、s depicted in Fig. 6. The pulse repetition frequency in this case was 12.5 MHz. In one period 212 samples are taken. Every sample point is averaged 640 times which causes a reduction of the jitter due to the phase no

21、ise of the local oscillator. This circuitry was assembled on Rogers Duroid RT6010 substrate. Figure 6. Down converted UWB radar pulse, phase shift with DDS. The measured conversion gain with a 3 dBm sinusoidal RF- input

22、 signal at different frequencies can be seen in Fig. 7. The Schottky diodes are unbiased in this case, reverse biasing would increase the bandwidth. The 3 dB cut off frequency is about 6.4 GHz. The result confirms tha

23、t the assumptions that have been taken agree quite well with the reality. The flat characteristic of the conversion gain arises from the large RF- input bandwidth of the used SPD. The break-ins at 4.2 GHz and at 5.3 G

24、Hz are probably caused by the used SMA- connectors. Figure 7. Conversion gain of the sampling down converter. V. CONCLUSION A new low cost sampling down converter for ultra- wideband radar applications with low sampling

25、rates using a sampling phase detector is presented. The circuit displays a conversion gain of 8 dB for a 6.4 GHz RF-bandwidth (without biasing the Schottky diodes). The impulse generator was realized with a new LO-fe

26、ed using a differential operational amplifier, which is possible up to some hundred megasamples per second. The LO-signal is transformed from single ended to balanced before generating the sampling pulses. This trans

27、formation in front of the SRD makes a broadband hybrid junction unnecessary. The use of the SPD for a sampling down converter is new. The SPD contains all necessary parts for pulse generation and sampling in one packa

28、ge and therefore allows a compact, low cost and simple to manufacture circuit. ACKNOWLEDGMENT This work was carried out at the Institute for Microelectronics (IME), Johannes Kepler University, Linz. We would

29、like to acknowledge Bernhard Mayhofer for his help in manufacturing the test hardware. REFERENCES [1] “First report and order, revision of part 15 of the commission’s rules regarding ultra wideband transmission systems

30、,” FCC, Washington, DC, ET Docket 98-153, 2002. [2] J.S. Lee, C. Nguyen, “A low-cost uniplanar sampling down-converter with internal local oscillator, pulse generator and IF amplifier,” IEEE Trans. On Microwave The

31、ory And Techniques, vol. 49, pp. 390-392, Feb. 2001. [3] J. Han, C. Nguyen, “Integrated balanced sampling circuit for ultra- wideband communication and radar systems,” IEEE Microwave And Wireless Component Letters, v

32、ol.10, pp. 460-462 Oct. 2004. [4] “Theory and application of sampling phase detectors,” Application Note APN5001, Skyworks Solutions, Inc.. Available: http://www.skyworksinc.com [5] Sampling Phase Detector Applicat