一.RF電路是針對哪方面?
射頻(radio frequency, RF)
舉凡低一點頻率AM FM收音機535khz-1605khz
高到 手機900~1900Mhz ~
最高的微波雷達5~30Ghz應用

二.RF理論
當操作頻率升高,其電磁波波長與電路元件(如電阻、電感、電容)的尺寸相近時,這些元件開始背離理想頻率響應的特性,
此時傳統電路分析理論(如克希荷夫定律)不再適合用來分析此高頻電路。
1.什麼頻率以上傳統電路分析不再適合?
2.什麼原因使電路元件的高頻特性不同於低頻特性?
3.新的分析理論是什麼?
4.如何應用新理論來從事高頻電路的設計

三.行動手機的關鍵元件:
1.antenna
2.RF switch
3.power amplifier (PA)
4.low-noise amplifier (LNA)
5.mixer
6.voltage-controlled oscillator (VCO)
7.filter (banspass, low-pass),
8.converter (ADC, DAC)
9.digital band band processor
[參考]:射頻微波電路設計 陳弘典 編著

四.RF電路內濾波器區分為
1.高通濾波器:頻率會過,低頻率會衰減
2.低通濾波器:頻率會過,高頻率會衰減
3.帶通濾波器:低頻率會衰減,中間頻率會過,高頻率會衰減
4.帶滯濾波器:低頻率會通過,中間頻率會衰減,高頻率會通過
匹配問題:因為RF電路內與電路內連接都要阻抗匹配,機器與天線阻抗在30MHz以下多為300Ω或50Ω
以前電視機在300MHz以下也有使用300Ω做為匹配但進年來已很少見了,目前都為75Ω
至於通訊機幾乎都是50Ω輸出輸入

五.匹配濾波器(matched filter)
In signal processing, a matched filter (originally known as a North filter[1]) is obtained by correlating a known signal, or template, with an unknown signal to detect the presence of the template in the unknown signal. This is equivalent to convolving the unknown signal with a conjugated time-reversed version of the template. The matched filter is the optimal linear filter for maximizing the signal to noise ratio (SNR) in the presence of additive stochastic noise. Matched filters are commonly used in radar, in which a known signal is sent out, and the reflected signal is examined for common elements of the out-going signal. Pulse compression is an example of matched filtering. It is so called because impulse response is matched to input pulse signals. Two-dimensional matched filters are commonly used in image processing, e.g., to improve SNR for X-ray.
[參考]:wiki

六.What is Matched filter used for ??
A matched filter is a filter used in communications to “match” a particular transit waveform.
 
Matched Filter is used to maximize the signal to noise ratio at the sampling point of a bit stream and to minimize the probability of undetected errors received from a signal.

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