霍夫曼碼(Huffman code)是一種無失真(lossless)的資料壓縮技術,普遍
應用磁碟操作系統(Disk Operation System),高畫質電視(HDTV),大資料
量傳輸(large data communication),及影像資料處理(Video coding),十
分重要,它是根據資料中各樣本(sample)間出現機率分佈不同,而給予不同
位元長度的字碼(codeword),來達成資料壓縮的效果。動態霍夫曼碼(
Dynamic Huffman Code)用於編碼解碼樣本機率分佈未被事先得知的任何
資料,且壓縮效果十分良好,並避免可調變式霍夫曼碼 (Adaptive
Huffman Code)需要大量暫存記憶體,及要傳送難以判讀的大量資料之缺
點,也改正靜態霍夫曼碼(Static Huffman Code)被限制使用於特定樣本機
率分佈的現象。動態霍夫曼碼編碼/解碼器電路複雜度極高,尚無有效而完
整的電路架構曾被發表出來,在本論文中我們提出一個 CAM 架構(the
CAM based architecture)來解決這個問題,且推算編碼器的效能(
thoughput)可達到 1 bit/cycle,並以此架構為基礎,製作一顆 DHC 編碼
器晶片,使用了 TSMC 0.8 um spdm 的製程,晶片面積為 4.8mm*4.8mm,閘
數目為 17652,工作頻率為 20 Mhz。

Huffman coding is a lossless data compression technique that
achieves compact data representation by taking advantage of the
statistical characteristic of the source. It is widely used in
many various data compression applications , such as high
definition television , disk operation system , video coding ,
and large data communication ....。 Dynamic huffman coding
(DHC) can compress any data file without preview. Compared with
the Adaptive huffman coding , the DHC method requires a fewer
memories and needs no side informations . Compared with the
static huffman coding , the DHC method achieves a better
compression ratio。 In this papper , the modified algorithm and
the CAM_based architectures for DHC have been presented . The
output thoughput of the encoder is 1bit/cycle . Based on the
architecture , the DHC encoder chip is implemented . The chip
has gate count of 17652 and die area of 4.8mm*4.8mm by using
TSMC 0.8um spdm process . From the result of timing analysis ,
the work frequency is about 20 Mhz。