開關電源(yuan)模(mo)塊(kuai)阻(zu)(zu)抗(kang)(kang)是指內部(bu)電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)、電(dian)(dian)(dian)(dian)(dian)容(rong)和電(dian)(dian)(dian)(dian)(dian)感(gan)(gan)組成的電(dian)(dian)(dian)(dian)(dian)路對(dui)交(jiao)(jiao)(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)起到(dao)阻(zu)(zu)礙作(zuo)用。電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)的阻(zu)(zu)抗(kang)(kang)就是其本(ben)身，電(dian)(dian)(dian)(dian)(dian)容(rong)電(dian)(dian)(dian)(dian)(dian)感(gan)(gan)兩者對(dui)交(jiao)(jiao)(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)的阻(zu)(zu)礙叫電(dian)(dian)(dian)(dian)(dian)抗(kang)(kang)。電(dian)(dian)(dian)(dian)(dian)容(rong)在(zai)電(dian)(dian)(dian)(dian)(dian)路中(zhong)對(dui)交(jiao)(jiao)(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)礙叫容(rong)抗(kang)(kang)，交(jiao)(jiao)(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)頻率越大，容(rong)抗(kang)(kang)越小(xiao)，有(you)隔直(zhi)通交(jiao)(jiao)(jiao)的作(zuo)用。電(dian)(dian)(dian)(dian)(dian)感(gan)(gan)在(zai)電(dian)(dian)(dian)(dian)(dian)路中(zhong)對(dui)交(jiao)(jiao)(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)礙叫感(gan)(gan)抗(kang)(kang)，交(jiao)(jiao)(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)頻率越大，感(gan)(gan)抗(kang)(kang)就越大，有(you)對(dui)交(jiao)(jiao)(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)通直(zhi)隔交(jiao)(jiao)(jiao)的作(zuo)用，可進行濾波(bo)。
　　電(dian)(dian)(dian)源模(mo)(mo)塊(kuai)(kuai)內阻較大(da)會不利(li)于負載穩(wen)壓(ya)(ya)電(dian)(dian)(dian)路(lu)工(gong)作，嚴重的(de)(de)負載電(dian)(dian)(dian)流任何變化都(dou)會導(dao)致模(mo)(mo)塊(kuai)(kuai)輸(shu)出的(de)(de)起(qi)伏，起(qi)伏對(dui)(dui)測試(shi)的(de)(de)影響和(he)(he)脈沖與噪聲對(dui)(dui)測試(shi)結(jie)果的(de)(de)影響一樣(yang)。當線電(dian)(dian)(dian)壓(ya)(ya)或負載電(dian)(dian)(dian)流變化時，直流電(dian)(dian)(dian)源模(mo)(mo)塊(kuai)(kuai)的(de)(de)輸(shu)出電(dian)(dian)(dian)壓(ya)(ya)會有(you)所起(qi)伏。穩(wen)壓(ya)(ya)程度由穩(wen)壓(ya)(ya)電(dian)(dian)(dian)路(lu)的(de)(de)參數，濾(lv)波電(dian)(dian)(dian)容容量(liang)和(he)(he)能量(liang)釋放的(de)(de)速率所決定(ding)，穩(wen)定(ding)大(da)小是空載或滿載時輸(shu)出電(dian)(dian)(dian)壓(ya)(ya)的(de)(de)百(bai)分比或變化值。
　　瞬態響應或(huo)恢(hui)復(fu)(fu)時(shi)間(jian)一般在(zai)負載變化10%時(shi)，常(chang)(chang)用輸出(chu)偏離(li)峰(feng)值(zhi)(zhi)電(dian)壓(ya)(ya)的(de)毫伏數標定輸出(chu)偏離(li)量，用輸出(chu)恢(hui)復(fu)(fu)到(dao)正常(chang)(chang)值(zhi)(zhi)所用毫伏數標出(chu)恢(hui)復(fu)(fu)時(shi)間(jian)。電(dian)源模塊瞬態響應和恢(hui)復(fu)(fu)時(shi)間(jian)的(de)大小表(biao)明輸出(chu)負載在(zai)突然變化時(shi)，穩壓(ya)(ya)電(dian)路恢(hui)復(fu)(fu)正常(chang)(chang)電(dian)壓(ya)(ya)能力的(de)大小，一般是用當負載突然發生變化時(shi)輸出(chu)的(de)偏離(li)值(zhi)(zhi)或(huo)是輸出(chu)恢(hui)復(fu)(fu)到(dao)原來值(zhi)(zhi)所用的(de)時(shi)間(jian)來標定。

　　阻抗匹(pi)配(pei)可(ke)以調(diao)整負載功率和抑制信號反射，信號源或傳輸線跟負載間達到合適搭配(pei)叫做(zuo)阻抗匹(pi)配(pei)。對于(yu)一個(ge)純電(dian)阻電(dian)路或低頻電(dian)路，電(dian)容電(dian)感(gan)的電(dian)抗值基(ji)本可(ke)以忽略，電(dian)路阻抗主(zhu)要來(lai)源電(dian)阻。

　　在高(gao)頻領域(yu)中(zhong)，當信(xin)號(hao)波長(chang)和傳輸線長(chang)處于(yu)相(xiang)同量(liang)級時，反射(she)信(xin)號(hao)易與原信(xin)號(hao)混(hun)疊，而阻抗(kang)匹配可以有效減少消(xiao)除高(gao)頻信(xin)號(hao)反射(she)。PCB走線阻抗(kang)主要來自寄生(sheng)電容、電感、電阻，因素有材料(liao)介電常(chang)數、線寬(kuan)、線厚和焊盤的厚度等。高(gao)頻領域(yu)中(zhong)信(xin)號(hao)頻率對PCB走線的阻抗(kang)值影響很大，當數字信(xin)號(hao)邊沿時間小(xiao)于(yu)1ns或模擬信(xin)號(hao)頻率超過300M就要考慮阻抗(kang)問題。
　　目前(qian)阻抗匹配的方法主要有改(gai)變阻抗力(li)(li)或調(diao)整傳輸線兩種(zhong)。改(gai)變阻抗力(li)(li)是指通過(guo)電(dian)容、電(dian)感(gan)(gan)與負(fu)載的串聯(lian)并(bing)聯(lian)調(diao)整負(fu)載阻抗值(zhi)，達(da)到(dao)源和負(fu)載阻抗匹配。調(diao)整傳輸線是加長源和負(fu)載間的距離，配合電(dian)容電(dian)感(gan)(gan)把阻抗力(li)(li)調(diao)為(wei)零。
　　開關電源目標阻抗是電源系統的瞬態阻抗，和一定寬度的頻段有關，在相同條件下，電源系統的頻率越(yue)大(da)，其阻抗越(yue)大(da)。