Transcript Department of Electrical Engineering, National Taiwan University

R.S.F.Q 的應用與未來
p.s.kuo
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
簡介


當今世界上最快的集成電路採用的是超導
金屬鈮，而非半導體化合物製造。該技術基於
約瑟夫森結(Josephson junction)元件和超導連接
間單個磁通量子的傳送。
這些工作在10K溫度下的超導IC，於1980年早
期研究的超導IC大有不同。正是在那些項目快
結束的時候，一些新發現導致第二代超導材料
和電路製造工藝的出現,發展出一種基於單個磁
通量子的儲存和傳輸，稱為快速單磁通量子
(RSFQ)的邏輯電路結構。
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
R.S.F.Q 基本原理

約瑟夫森效應於1962年由約瑟夫森提出，1963年由安
德孫和夏皮羅實驗証實。現代約瑟夫森元件由兩層超
導薄膜及中間的絕緣層構成，電子對因穿隧效應穿越
絕緣層，在超導體內引起電流。

RSFQ電路中代表信號位的不是靜態電壓，而是磁通量
子的存在與否。
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
R.S.F.Q 基本原理


RSFQ電路不直接利用逃逸的量子，而是依靠磁通量子
進入或離開環路時在Junction中產生的短電壓脈衝。如
約瑟夫森結為1um邊長的方形，電壓脈衝持續時間約
1ps，幅度2mV。隨結尺寸減小，SFQ脈衝變窄，但幅
度-時間乘積保持不變2mV-ps {2x10-15韋伯 }。
電壓脈衝可通過微傳輸線或主動約瑟夫森傳輸線快速
傳輸到其它們。所有傳輸都是超導的，損失極小，時
鐘頻率高達750GHz。
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
R.S.F.Q 的主要優點



RSFQ technology ,one of the superconductor Josephsonjunction digital technologies,has attracted significant attention because
of(1)high speed
(2)low power operation
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
R.S.F.Q 的主要優點

Extremely high operation speed
clock period :
(1) 10-20pS(100GHz) for fabricated
3 3 2 Nb / Al2O3 / Nb
Josephson junction while bit error is well below 3 1015 bit 1
(2) as small as 1-2pS if submicron niobium
technology were used----------Theoretical.
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
R.S.F.Q 的主要優點

Power consumption
Source :
(1) energy dissipation inside the Josephson junction :
1018 joule/ bit -----很小
(2)dissipation in dc current supply resistors : 1W per
gate -----比較大
與矽元件之比較 : 0.8μm 100GHz的RSFQ元件功率消耗約為普通矽元
件的十萬分之一。
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
R.S.F.Q 的其它優點

精度高:
交流約瑟夫森效應使得可用簡單的電壓測量導出輸出磁
通量子的頻率.
電路密度高 : Josephson-junction
超導連接
功率消耗～0 ∴可密集封裝而不會過熱
信號傳輸幾乎無色散:可改善晶片中互連相關的延遲-----進而
增加時鐘(clock)速度
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
用R.S.F.Q 做成的邏輯 (1)
AND function F=(A+B) ×(C+D)
AND circuit
(a) equivalent circuit
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
用R.S.F.Q 做成的邏輯(1)
(b) Dynamics for two set of data :
{A=B=1,C=D=0} and {A=C=1, B=D=0}
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
用R.S.F.Q 做成的邏輯(1)

(1)A=B=1,C=D=0 :
J3 “1” state
SFQ is applied to J5,J7
but Ic5<Ic7
no output pulse
J4 “0” state

(2)A=C=1,B=D=0 :
J3 “1” state
J3,J4 are switched simultaneously
SFQ inject to J7 through L1,L2
J4 “0” state
Ic5+Ic6>Ic7
output pulse produce
Ic : critical current
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
用R.S.F.Q 做成的邏輯(2)
XOR cell
Two storage interferometers:
:J1, J3, L1, J5, J7 And J2, J4,
L2, J5, J7 which are biased
by Ib1 and Ib2 .
(a) Equivalent circuit
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
用R.S.F.Q 做成的邏輯(2)
(b)State transition diagram of XOR
Ic5<Ic3+Ic4 ;
State “10” , A輸入
“1”, J5 transit to
initial “00” state
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
用R.S.F.Q 做成的邏輯(3)

Template circuit of a subfamily of B flip-flop.
A
Q1
R1
"1"
Q2
R2
"1"
Q1
S1
"0"
Q2
S2
"0"
R1
R2
"1"
A
S1
S2
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
"0"
RTO
RTCVD
poly
RTCVD
nitride
用R.S.F.Q 做成的邏輯(3)
state transition diagram
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
Dual –rail logic gate based on RSFQ cells

目的 : RSFQ 的靈敏度受限於電路參數和電源供應變異的影響,
尤其在極高頻時,時鐘(clock)脈衝的分佈將更為複雜.為解決此一問
題,我們可使用dual-rail 資料型式的非同步資料驅動閘.

缺點 : 硬體使用量大
for example :
44 Josephson junction for dual-rail gate
XOR gate :
only 9 junctions for classical RSFQ gate
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
Dual –rail logic gate based on RSFQ cells

General structure of two-input data-driven dual-rail ligic gate
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
Dual –rail logic gate based on RSFQ cells
Optimum solution :
Using the clock-driven logic for “local” computations in
the blocks,and dual-rail logic to exchange the data betweem blocks
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
On-chip and off-chip
Package 的重要性 :
perform ance of on  chip
 1000
perform ance of off  chip
RSFQ 技術可望解決現今on-chip的問題,使的CPU速度大為提昇
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
SFQ pulse 的傳輸

Josephson junction
impedance matching

Superconductor
allows ballistic transfer of SFQ pulses between them
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
SFQ pulse 的傳輸

For S  4  4 μ
2
critical current I C  125A
Z  2
On-chip ballistic transfer of SFQ pulses
along superconductor microstrip lines
未來的用途: SFQ pulse transfer between chip to chip
+
superconductor microstrip lines are used as chip
interconnects
foup
Department of Electrical Engineering, National Taiwan University
Clean
Module
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
Chip-to-chip ballistic pulse transfer
 Equivalent circuit of chip interconnects
L will distort and reflect
the fast rise signal pulses
Minimize the L effect :
adding ground capacitors
between L and Z
C  L / 2Z 2
on each side of L to match the Impedance
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
Chip-to-chip ballistic pulse transfer

Limitation of L value :
 s  3   3 2 LC  3L / Z
s :
time constant of incoming
pulses
  : delay time through the connector
Typical values:  s  5 ps
Z  2
L  3 pH
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
Multiple Flux Quantum(MFQ) pulses

目的 :
為了提高L的最大容許值 ,必須使用具有高阻的傳輸線
-------方法 : 使用由多個Josephson junctions 堆疊而
成的驅動器以產生MFQ脈衝.
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
MFQ driver
N nonlatching superconducting
quantum interferometers
connected in series
equivalent circuit of MFQ driver
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
MFQ driver

Output
:
sum of simultaneous SFQ pulses produced by N
superconducting quantum interferometers
Input : SFQ pulses
Interferometer : magnetically controled by the corresponding output
of an SFQ splitter
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
MFQ driver

Result of using MFQ driver :
L can be as large as 20～30 pH
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
R.S.F.Q 的主要應用
(1)包含了2500多個約瑟夫森結

基於相位調制/解調結構的
RSFQ高精度A/D轉換器
(2)工作時鐘為12.8GHz。
(3)再結合超導A/D的量子級精度
超導A/D轉換器的性能已超過以往任何技術。
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
R.S.F.Q A/D 轉 換 器 的 特 性
寬頻動態可編程性能 : 用戶可以時時在位寬度和帶寬之間做平衡 ;
與此相比，半導體A/D轉換器則很少針對幾種工作頻率設計
應用
寬頻通信和雷達系統中，特別是全軟件無線電實現的無線通信
優點
提高接收靈敏度和精度，可簡化手機和終端的配置要求。
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
結論

商業化前景 :
(1) RSFQ不需要昂貴的製造設備,在矽晶片製造中幾
乎過時的1μm級設備就夠了，而且RSFQ元件的製造本身比任何半
導體製造都簡單，不需要包括外延生長、摻雜或離子注入在內的
複雜步驟,僅需要在矽晶圓片上濺射超導薄膜和絕緣層，而晶圓可
保持在接近室溫 ----------------------------製程便宜且容易。
速度是目前最快半導體IC的100倍，所有技術都需要考慮到電
磁信號的分布式本質。
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
結論
(2)市場對高頻寬應用的需求------促使超導RSFQ技術和當前已近
極限的半導體製造技術結合。
(3)最大的問題 :
為了做大尺寸的RSFQ系統, 封裝(packaging)是最大需
克服的難題, 而解決的方法就是使用 SFQ/MFQ drivers
Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride
Reference

(1) Stas Polonsky. RSFQ: What we know and what we don’t . SUNYStony Brook Physics Department. Stony Brook,NY 11794-3800

(2) 《世界電子元器件》2月號
(3) O.A.Mukhanov, S.V. Polonsky ,and V.K.Semenov.
New elements of the RSFQ logic famaily .
IEEE Trans. on Magnetics, vol. 27, NO. 2, March 1991.

Clean
Module
foup
Department of Electrical Engineering, National Taiwan University
Load
lock
ellipsometer
RTO
RTCVD
poly
RTCVD
nitride