b: Fig. 1. (a) Basic circuit of subharmonic mcillator. (b) Ideal characteristic of nonlinear element.period of the output voltage waveform is 2r/wo seconds, so that if the second current step occurs r / w 0 seconds after the first, the two desaying sinusoids are directly in phase and therefore add. The cycle ABCDEDFBA is then repeated.Thus, in the steady state, an output oscillation is maintained across the tuned circuit by the periodic switching of current pulses from the nonlinear element. Detuning of the output circuit results in a reduction of amplitude of the output oscillation, but the output frequency is still of the formfi/n. By tuning the output to harmonics of the fundamental component of the current waveform, it is possible to generate frequencies which are rational fractions of the input frequency.Stable operation of the circuit with power gain is possible, power gain being defined as the ratio of the power developed at subharmonic frequency across the load resistance to the power flowing into the input terminals at the driving frequency. A further advantage of the circuit over other methods of subharmonic generation is its ability to produce high orders of frequency division. (An output frequency 1/2000Xthe input freqatvlcy has been obtained in practice.)The two circuits described below give fairly close approximations to the characteristic of Fig. lThe current-voltage characteristic of a tunnel diode can be considered to be composed of three sections, two with positive slope and one with negative s1ope:The effect of combining the tunnel diode with a resistor R in series is to increase the reciprocals of the slopes of the three sections by a value R. The approximation to the current-voltage characteristic of Fig. l(b) is obtained by setting the value of R greater than the inverse of the absolute value of the slope of the negative resistance section.The second configuration, presented in Fig. 2(a), is based on a circuit described by Ostefjellsl for the generation of a linear negative resistance. In the saturation and active regions of the matched transistors T I and T2, diodes D l and D 2 have no effect since they are reversebiased with their terminals open-circuited. In the cutoff region, when the current through RE is almost reduced to zero, resistors Rd are sufficient to forward-bias D l and Dz. Tl and T2 are now bypassed and current i flows through D l , &, Dfr and R. Fig. 2(b) shows the current-voltage characteristic of the circuit of Fig. 2(a). Rb provides a means of altering the value of u at which the active region ends by varying the voltage levels on one side of the diodes D I and D2 and thereby controlling the value of u at which the diodes become forward-biased. Rb is set to a value such that section BE of the transistors," Proc. fEEE(Correspondence). voI. 53, p. 404, April 1965. 1 S. Ostefplls, "Negative resistance circuit using two complementary field effect -/ d (b) Fig. 2. (a) Transistor-diode arcuit for generating nontinear characteristic. (b) Characteristic of the circuit in Fig. 2(...

No abstract

A highly manufacturable I l0nm Embedded DRAM technology with stack A1,03 MIM capacitor has been demonstrated successfully for the first time. High-density DRAM core with 0.1pm2 cell size and high performance logic circuits have been realized at the same time by separation of the gate pattern at memory cell and peripheral logic region. Low temperature BDL process, highly reliable A124 MIM capacitors have been developed to control process temperature. DRAM cell performance has been improved by introducing tungsten wordline, CoSi, plug and tungsten bitline. 7 levels Cu and CVD-OSG low-k material have been implemented to satisfy the requirement of high performance logic circuits design.

No abstract

No abstract