Analysis of a source-coupled MOS multivibrator with resistive drain loads

The determinant of the system of nodal equations of a source-coupled MOS multivibrator is calculated. Equating this determinant to zero, one can obtain the condition of transition from one quasistable state to another. This condition is used to calculate the currents in the multivibrator transistors at the instant of transition. Then the voltage amplitude at the coupling capacitor is calculated and the oscillation frequency is found. The oscillation frequency in this multivibrator depends on the value of currents supplied to the circuit and the power supply voltage. The results were verified experimentally.     

New constant-current controlled astable multivibrator for generating sawtooth and square waves

This article presents a now constant-current controlled astable multivibrator in which only one resistor and one capacitor is used, the other elements being transistors. The circuit consists of a constant-current source and the multivibrator itself. The multivibrator is specifically designed to have a simple three-stage direct-coupled transistor amplifier, with the output of the third stage fed back to the first stage and a capacitor connected across any two collectors. The switching action takes place by means of that capacitor. Linear sawtooth and square waves are generated simultaneously at the transistor collectors. Since only one resistor and one capacitor are required, this circuit is practical with IC fabrication.     

A low-power 128-MHz VCO for monolithic PLL ICs

The phase-locked loop (PLL) is implemented by 2-μm bipolar-CMOS (BiCMOS) technology. The power dissipation of the PLL and the voltage-controlled oscillator (VCO) are 100 mW at 64 MHz and 25 mW for 1-128 MHz clock frequencies, respectively. The linearity of the VCO is ±0.5% and the temperature stability is ±50 p.p.m./°C. The center frequency of the VCO is accurately set by using one fixed external resistor. The VCO has an advantage of noise insensitivity. To achieve these features, the VCO design uses an emitter-coupled multivibrator with a built-in timing capacitor and a controlled oscillation loop gain. The PLL can be applied not only to timing recovery for data transmission, but also to frequency synthesis and self-clocking for data recording     

Analysis of emitter (source)-coupled multivibrators

The popular emitter-coupled multivibrator and its MOS variant are analyzed using the classical discontinuity theory. Accurate formulas for predicting their relaxation oscillation are obtained solving the nonlinear circuit equation, which is derived finding the voltage-current characteristic of the nonlinearity connected to the timing capacitor. Then, using a small-signal equivalent circuit accounting for the intrinsic capacitances of the devices, we investigate the high-frequency behavior of these circuits finding the oscillation start-up condition. We show that they can exhibit a completely different behavior, similar to a series LC-tuned oscillator, without using an inductor. Numerical simulations are performed showing that the presented formulas are more accurate than the existing ones and that both behaviors are possible.     

A novel CMOS multivibrator

The paper describes a CMOS multivibrator using a differential pair with positive feedback via a current mirror and a diode-connected NMOS transistor; the output voltage is taken at this transistor. The timing capacitor is charged by a current source and discharged by the differential pair tail current. During capacitor charging the tail current is steered into the current mirror. The mirror output current is applied to a diode-connected transistor and creates the HIGH level of the output voltage. During discharging the diode connected transistor obtains a small current (from another current source) which determines the LOW level of the output voltage. The capacitive loading and frequency limit are investigated. The design procedure is given. The body effect does not affect the circuit performance. This allows to reduce the multivibrator area.     

Stability of oscillation frequency of ECL-based multivibrator

The stability (with temperature and power supply voltage variations) of the oscillation frequency f₀ of an ECL-based multivibrator is considered. This circuit is a non-saturated multivibrator. Its operation is revised and an exact expression for calculation of f₀ is obtained. Then the temperature coefficient and sensitivity to the power supply voltage are derived. The results were verified experimentally. Some recommendations on the choice of the external timing components are given.     

一种高稳定性的振荡电路

文中设计了一种高稳定性的振荡电路,其主要由电流模带隙基准,电压比较器和电容充放电电路构成。带隙基准产生三组基准电压,一组用于生成振荡电路中电容的充电电流,一组作为比较器的判决门限,另一组用于产生振荡部分的工作电压。电压比较器门限和充电电流的大小控制振荡电路的振荡频率。整个电路采用SMIC 0.18μm CMOS工艺实现。通过Hspice仿真,在-20℃~70℃、1.8V~3.8V工作范围内振荡精度在1%左右。     

单运放多谐振荡器

分析了一种由单运算放大器构成、电路中包含二个充放电回路的多谐振荡电路，并对振荡信号的波形和输出信号的振荡频率进行了讨论，得到了计算公式；对振荡电路进行了实验分析，测试结果说明了理论分析的正确性。     

Physical random number generator based on MOS structure after soft breakdown

We present a novel physical random number generator (RNG) that uses a metal-oxide semiconductor (MOS) capacitor after soft breakdown (SBD) as a random source. It is known that the electrical properties of MOS capacitors after SBD show large fluctuation. When the resistor in an astable multivibrator is replaced with an MOS capacitor after SBD, the multivibrator converts the noise signal into a rectangular wave whose period fluctuates randomly. A 1-bit counter and a flip-flop are used to generate random numbers from the fluctuating rectangular wave. Some high-level tests indicate that the generated random numbers have excellent quality for cryptographic applications. Even though our circuit is small and can be constructed using about 20 complementary-MOS logic gates and several passive devices, high-quality random numbers such as those generated by large physical RNGs can be obtained.     

A novel variable frequency sinusoidal oscillator using a single current conveyor

A new active RC second-order sinusoidal oscillator using a single second generation current conveyor is described. A single grounded resistor adjusts the circuit for oscillation and a single grounded capacitor controls the oscillation frequency without affecting the oscilllation condition.     

Switching Time in Relaxation Oscillations of Emitter-Coupled Multivibrators

This paper gives an estimation of the switching time between on and off transistor states for the emitter-coupled multivibrator. The calculation uses the root locus of the characteristic equation for the oscillator small-signal equivalent circuit, while changing the device current as a parameter. The switching time is found using a fitting location of the root in the right half of the $s$-plane. The oscillation frequency is also obtained. The approach provides a further insight into switching behavior of relaxation oscillators, gives an accurate estimation of the oscillation frequency, and allows one to establish a useful connection between sinusoidal and relaxation oscillators. The theoretical results are confirmed by simulations.      

The observation of coupling between low- and high-frequency resonances in a bounded plasma

The coupling between low- and high-frequency resonances of a plasma capacitor is discussed. A low-frequency ion oscillation is found to cause the zero-order density profile to vary at ωi. This variation of the density profile causes the third-harmonic output of the capacitor to be frequency modulated.     

Sinusoidal and Relaxation Oscillations in Source-Coupled Multivibrators

The paper considers the differential equation describing sinusoidal and relaxation oscillations of the source-coupled multivibrator. The transition from one form of oscillations to another, when the coupling capacitor is increasing, is explained by modifications in the shape of the central branch of the isocline of horizontal tangents on the phase plane of this differential equation. The formulas for amplitude and frequency calculations in sinusoidal operation are found. The calculations of transistor switching time and period for relaxation oscillations are provided as well. The results were verified in simulations.     

射频连续波对多谐振荡器的干扰研究

在GTEM室中用射频连续波对某导弹装备上的一块数字控制电路进行电磁辐照实验,在一定的场强下,产生控制信号的自激多谐振荡器受到了电磁干扰,主要表现为产生的方波控制信号占空比增大。分析了多谐振荡器受干扰的机理,用电路仿真软件对多谐振荡器受到的干扰进行了模拟,验证了对干扰机理的分析。     

并联谐振吸收网络在X波段MMIC LNA消除振荡中的应用

为消除X波段单片集成(MMIC)低噪声放大器(LNA)设计中在低频端产生的振荡,提出了在第三级PHEMT管的栅极和地之间放置LC并联再串联电阻的吸收网络的方法.由于吸收网络与PHEMT管的输入电容组成的回路谐振在工作频带内的高频端,因此,降低了带外低频端的高增益,从而消除了多级级联LNA电路中由于低频端增益过高产生的振荡,而电路的噪声性能并没有明显变化.     

A 94/47 GHz frequency halver using a GaAs Gunn device

This paper describes the basic principles and the set up of a new kind of frequency halvers suited for millimeter wave applications. A Ga As Gunn-device is used to act like a nonostable multivibrator having a hold time adequate to the domain transit time T_t of the Gunn-device. In a certain frequency range depending on the transit frequency f_T=1/T_T, bias voltage and circuit parameters a harmonic wave synchronized fundamental/2nd harnonic mode oscillator is able to perform as a frequency halver. An input power of only 1mW is sufficient to achieve a bandwidth of 5 GHz respectively 2.5 GHz centered around 94 GHz respectively 47GHz. Since the output power is 50 mW at fundamental frequency f_F, this halver offers 17dB conversion gain.     

New quartz multivibrator

A new quartz multivibrator having a frequency stability better than 0.0005 percent between 3 and 12-V supply voltage is described. The temperature variations influence the multivibrator frequency as claimed for the crystal itself--the influence of the circuit is negligible.     

New canonic lossy inductor using a single CDBA and its application

A new lossy inductor (parallel R-L type) using single current differencing buffered amplifier (CDBA) is presented, which employs only two resistors and a grounded capacitor. The proposed lossy inductor is shown to be useful in realizing an oscillator circuit, which provides quadrature voltage outputs using only two CDBAs, three resistors and two grounded capacitors and offers independent control on condition of oscillation and frequency of oscillation up to a frequency of 61 MHz. Detailed non-ideal analysis including single-pole model for voltage and current gain has also been carried out. SPICE simulation results and experimental results based upon the CDBA constructed from commercially available IC AD844 have been included which confirm the practical workability of the proposed lossy inductor and quadrature oscillator circuit.     

一种跨导线性化低相噪压控振荡器

介绍了一种跨导线性化的宽带压控振荡器,由谐振腔电路、偏置电路、可编程电容阵列组成。提出一种通过电容隔直将有源器件进行交叉耦合的谐振腔结构,实现了有源器件的跨导线性化,大幅减小了有源器件自身的固有噪声,改善了压控振荡器的相位噪声特性。通过可编程电容阵列电路,可在压控振荡器内进行频率调节,扩展了振荡频率范围。测试结果表明,压控振荡器的振荡频率覆盖5 400~7 300 MHz,频率覆盖比达26%,在7 300 MHz时,相位噪声达到-128 dBc/Hz@1 MHz。该压控振荡器可作为高性能频率合成器的核心器件,构成本振信号源,可被广泛应用于无线基站、频谱监测等多种领域。     

回转器在振荡电路中的应用

本文叙述应用回转器的振荡电路的原理与实践.将运算放大器及其外接元件组成回转器,就能够模拟一只Q值极高的大电感,从而实现超低频振荡.这种等放电感的电感量可达1MH,甚至更高!如果将模拟电感与适当的电容组成并联谐振回路,它的振荡频率很容易低于1Hz.在此回路两端接上正反馈回路,就能维持稳定振荡,而且波形良好.电路输出可以作为标准信号,用来校准医用微分器,作生理电脉冲波形变换的研究.