Tank Capacitor Research Articles

Stable adiabatic circuit using advanced series capacitors and time variation of energy dissipation

We discuss the stability of an adiabatic stepwise-charging circuit with advanced series capacitors, which is effective for the reduction of the applied voltage to each capacitor. SPICE simulation shows that this circuit is stable even if the initial voltages are lower than zero. For the analytical discussion, we derive a matrix that connects charge and voltage in the circuit and show that the matrix is a positive-definite symmetric one. Therefore, the step voltage is generated spontaneously. We also derive energy dissipation analytically using tank capacitor voltage. Using this formula and SPICE simulation, we clarify that energy dissipation decreases monotonically as a function of time and finally reaches the minimum value.

Recent Progress in Adiabatic Circuits

Adiabatic operation promises large reductions of power consumption because it does not dissipate energy. This paper reviews recent progress in adiabatic circuits. First, a charge recycle regenerator with the tank capacitor is discussed. Next, an adiabatic charging binary decision diagram circuit is discussed. In the circuit, a gate-level pipeline can be realized by using four charge-recycling clocks. Also reviewed is an adiabatic circuit based on clocked energy reversible logic, which can maintain the complementary-metal-oxide-semiconductor circuit architecture. Finally, adiabatic staticrandom- access-memory is covered, which is structurally close to the conventional SRAM. These adiabatic circuits are very effective in the nanoscale region because they can avoid hot carrier effects and electromigration owing to their gradual charging characteristics. This review also covers some important recent patents.

Zero-Voltage-Switching DC–DC Converters With Synchronous Rectifiers

Active resonant tank (ART) cells are proposed in this paper to achieve zero-voltage-switching (ZVS) and eliminate body-diode conduction in DC-DC converters with synchronous rectifiers (SRs). In low-output-voltage DC-DC converters, SRs are widely utilized to reduce rectifier conduction loss and improve converter efficiency. However, during switches' transition, SRs' parasitic body diodes unavoidably carry load current, which decreases conversion efficiency because voltage drop across body diodes is much higher than that across SRs. Moreover, body diodes' reverse recovery leads to increased switching losses and electromagnetic interference. With the proposed cells of an ART, the body diode conduction of the SR is eliminated during the switching transition from a SR to an active switch, and thus body diode reverse-recovery-related switching and ringing losses are saved. An ART cell consists of a LC resonant tank and an auxiliary switch. A resonant tank cell is charged in a resonant manner and energy is stored in the capacitor of the tank. Prior to a switching transition from a SR to an active switch, the energy stored in the tank capacitor is released and converted to inductor current, which forces the SR current changes direction to avoid conduction of the body diode and related reverse recovery when the SR turns off. Moreover, at the help of energy released from the ART, the active switch's junction capacitance is discharged, which allows the active switch turns on at ZVS. Since energy commutation occurs only during switching transition, conduction loss in the ART cell is limited. Moreover, the auxiliary switch turns off at ZVS and the SR operates at ZVS. The concept of ART cells is generally introduced and detailed analysis is presented based on a synchronous buck converter. Experimental results show the proposed ART cell improves conversion efficiency due to the reduced switching loss, body diodes' conduction, and reverse-recovery losses.

A Magnetically Tuned Quadrature Oscillator

Continuous frequency tuning by control of the magnetic field of a transformer - capacitor tank, in a selective oscillator, is explored in this work. A quadrature generator is built connecting two identical transformer - capacitor oscillator cells in a feedback loop. The topology itself assures the currents in the transformer windings are aligned in phase, while their relative amplitude determines, via magnetic coupling, oscillators' tank reactance, i.e., oscillation frequency. This paper introduces the idea, analyzes oscillation amplitude, frequency tuning band, phase noise, and phase accuracy, and discusses design and experiments. Prototypes, realized in 65 nm CMOS, employing MOS varactors to further extend operation bandwidth, show the following performances: 3.2 GHz and 7.3 GHz minimum and maximum oscillation frequency, respectively. Phase noise figure of merit of 176.5 dB at 3.2 GHz and 170.5 dB at 6.4 GHz is observed, with 24 mW maximum power consumption and 1.5 maximum deviation from quadrature.

The use of commercial thyristors in repetitive high voltage switching devices for plasma sources

This paper presents a commercial high voltage thyristor used as a switch allowing a tank capacitor to discharge in a load. In classical high power pulse technology applications the output voltage pulse has to be characterized mainly by its crest value, its rise-time, the period the thyristor is held in the on-state and the fall-time. These parameters are studied as a function of the power circuit and of the trigger circuit. The thyristor presents two behaviours: the main is either higher or lower than the latching current. The low current behaviour is extensively investigated as it allows repetitive operation of the device. Two pulse power applications triggering electrical discharges are presented. Each one necessitates a specific pulsed power supply using series thyristor stacks or Marx structures. The first pulsed source delivers negative pulses with a crest voltage V oM = -35 kV, a turn on capability of T r = 90 ns and a repetition rate F = 900 Hz. The second is built using Marx structure and is characterized by V oM = 60 kV, T,. = 250 ns, F = 900 Hz.

Stability of adiabatic reversible charging using 1D-capacitor array between the power supply and ground

The stability of a new adiabatic stepwise charging circuit is discussed. Tank capacitors are connected in series between the power supply and ground. This circuit features immediate operation using a stepwise waveform, even if the tank-capacitor value is considerably larger than the load capacitance. This immediate operation is possible because stepwise voltage is formed immediately due to the voltage division by series capacitances. For the analytical discussion, we derive a voltage equation that connects the initial state and the final state after the charge-recycling process. It is proved that the eigen value of the matrix is smaller than 1. Therefore, a step waveform is spontaneously generated after many charge-recycling processes.

Polyphase Boost Converter with Digital Control

Boost d.c.-d.c. converters have very good source interface properties. The input inductor makes the source current smooth and hence these converters provide very good EMI performance. On account of this good property, the boost converter is also the preferred converter for off-line UPF rectifiers. One of the issues of concern in these converters is the large size of the storage capacitor on the dc link. The boost converter suffers from the disadvantage of discontinuous current injected to the load. The size of the capacitor is large. Further, the ripple current in the capacitor is as much as the load current; hence the ESR specification of the tank capacitor is demanding. This paper presents the polyphase boost converter, which overcomes the problem of high ripple current in the tank capacitor, which has not been discussed earlier. Comparison between the specifications of single stage and multistage is thoroughly examined. Digital control is more convenient for such a topology on account of the requirement of synchronization, phase shifted operation and current balancing. The control method is simpler and faster than its original form [10]. It does not depend on the previous duty ratio and it has been tested on four boost converters in parallel. Each is a 35W unit switched at 200 kHz. Experimental results in digital control, synchronization operation and current sharing are presented. The control method is implemented using a TI’s general purpose Digital Signal Processor eZdspF2812. This control scheme is applicable for PFC rectifiers as well.

A varactor configuration minimizing the amplitude-to-phase noise conversion in VCOs

Amplitude-to-phase-noise conversion due to varactors can severely limit the close-in phase noise performance in LC-tuned oscillators. This work proposes a rigorous analysis of this phenomenon, which highlights the fundamental limitations of single-ended tuned and differentially tuned diode varactor configurations. The back-to-back varactor topology is identified as a suitable solution to linearize the tank capacitance. The amplitude to phase noise conversion is greatly attenuated and the 1/f3 phase noise is drastically reduced, without impairing the achievable tuning range. These results are validated through circuit simulations in an existing 0.35-mum CMOS technology

Analysis of the stability of adiabatic reversible logic using the theory of normal modes in coupled oscillators

The stability of adiabatic stepwise charging reversible logic is discussed from the viewpoint of coupled oscillators. For adiabatic logic with asymmetric tank capacitors, we derive a matrix that connects the initial voltage with the voltage change after the charge-recycle process. This matrix is the same as the mechanical oscillator matrix of a string with equally spaced beads having different mass. From the theory of normal modes in coupled oscillators, it is proved that the eigenvalue of the matrix connecting the initial voltage with the final one is less than 1, which shows that a step waveform is spontaneously generated after many charge-recycle processes.

The stability of adiabatic reversible logic using asymmetric tank capacitors and its application to SRAM

The stability of adiabatic stepwise charging reversible logic is discussed. In the case of adiabatic logic with asymmetric tank capacitors, we derive a matrix which connects the initial state and the final state after the charge-recycle process. From the analytical discussion, it is proved that the absolute value of the eigen value of the matrix is less than 1. Therefore, it is shown that a step waveform is spontaneously generated after many charge-recycle processes. Next, an adiabatic stepwise charging SRAM is proposed. The SRAM is immune to hot-carrier effects and electromigration even in the less-than-45-nm process, while it maintains an operating voltage of 1V or more. The SRAM is suitable for nanoscale circuits.

A robust 43-GHz VCO in CMOS for OC-768 SONET applications

In this paper, we present a 43-GHz LC-VCO in 0.13-/spl mu/m CMOS for use in SONET OC-768 optical networks. A tuned output buffer is used to provide 1.3 V/sub p-p/ (single-ended) into a 90-fF capacitive load as is required when the VCO is used in typical clock and data recovery (CDR) circuits. Phase noise is -90 dBc/Hz at a 1-MHz offset from the carrier; this meets SONET jitter specifications. The design has a tune range of 4.2%. The VCO, including output buffers, consumes 14 mA from a 1-V supply and occupies 0.06 mm/sup 2/ of die area. Modern CMOS process characteristics and the high center frequency of this design mean that the tank loss is not dominated by the integrated inductor, but rather by the tank capacitance. An area-efficient inductor design that does not require any optimization is used.

A 5.7 GHz interpolative VCO using InGaP/GaAs HBT technology

A 5.7 GHz monolithic interpolative voltage-controlled oscillator using InGaP/GaAs HBT technology is demonstrated for the first time. Frequency tuning is achieved by changing the open loop gain instead of the tank capacitor. The experimental result showed that a 500 MHz tuning range at 5.7 GHz was realized, which can meet the requirement of 5.7 GHz ISM band.

A new class of quasi-square-wave resonant converters with ZCS

A new class of single-switch zero-current switching and clamped current (ZCS-CC) d.c.–d.c. converters is proposed. These converters can be realized by connecting a resonant tank inductor and a diode in series with the active switch in a conventional PWM converter, while a parallel combination of a filter inductor and a tank capacitor is connected in series with the freewheeling diode. All the semiconductors in these converters switch at ZCS-CC with minimum current stress, while the freewheeling diode turns on at ZVS. Moreover, the variation in the semiconductors voltage stress is relatively low at full and minimum load. The steady state characteristics for the complete class are analysed and verified.

Operation analysis of series resonant DC-DC converter with clamped tank capacitor voltage.

Operation analysis of series resonant DC-DC converter with clamped tank capacitor voltage.

Steady-state analysis and design of the parallel resonant converter

Five basic operating modes of the parallel resonant converter are analyzed. Three of the modes occur when the output filter inductor is removed and the remaining two occur when the filter inductor is large. Closed-form solutions are found for the two most important modes. Analysis results are given graphically so that the designer can use them without lengthy calculation or computer iteration. Switching frequency, peak tank capacitor voltage, and peak tank inductor current are plotted in the output plane. These plots, with a load line superimposed, show how operating point, frequency, and peak stress vary as load conditions change. Use of the output plane plots to minimize component costs is explained. Comparison of the best designs found for the large and zero filter inductance cases shows that removing the filter inductor can reduce both parts count and tank circuit size while peak transistor current remains unchanged. >

Linear Fluid Resistance Using Switching Valves and a Tank

An active linear fluid resistance is demonstrated using the switched capacitor concept from electronics. For the analogous fluid component, this requires using switching valves to alternately fill and empty a tank. Analysis shows that the equivalent linear resistance is directly proportional to the switching period and inversely proportional to the tank capacitance. For fluid components, the linearity is restricted to those cases where complete filling and emptying is achieved. The time period required to insure linearity is derived in terms of fluid circuit variables. As a result, there is a lower limit on the magnitude of resistance that can be obtained for a given fluid circuit. This magnitude depends on circuit component values, as well as on the desired operating pressure range. However, the net result is that we may construct a linear fluid resistance that has no dependence on orifice sizes, discharge coefficients, or Reynolds number. The experimental fluid circuit contains a source volume in addition to the switching values and tank required for the resistance component. The source volume filters the transients and permits steady state measurements. Experiments are performed for resistances with different switching periods and tank volumes. The experimental resistance values are always within 5 percent of the theoretical predictions. The switched capacitor concept may prove useful in the design of mass flowmeters, frequency-to-analog converters, electric-to-pneumatic transducers, and temperature sensors.

Design Equations for Dynamitron Type Power Supplies in the Megavolt Range

The power supply which is used as the accelerating potential for megavolt Dynamitron accelerators is a parallel-fed, series-cascaded rectifier system. Low frequency RF voltage is capacitively coupled into the cascaded rectifier system by means of an SF-6 gas insulated electrode configuration. Maximum voltage attained with this configuration has been 5.7 MV. Maximum current attained has been 20 mA. Maximum beam power attained has been 40 kW. This paper covers the development of equations which express the operational input parameters such as, oscillator plate voltage, current, and power in terms of the required output high voltage and load current, and the internal circuit parameters such as, tank capacitance, tank inductance resistance, number of rectifier stages, and oscillating frequency. Calculated data from these equations agree closely with experimental data. This analysis allows the optimization of a power supply design in terms of critical parameters for a given maximum output voltage and load current.

The Effect of Q on Power-Amplifier Efficiency

With class-A operation, loaded-plate-circuit Q does not affect plate efficiency. With extreme class-C operation, Q has a considerable effect. A Q of 50 is required to keep loss in efficiency below 3 per cent. To obtain full benefit from the tank capacitor it must be connected directly from plate to cathode. Connecting the plate or cathode to a tap on the plate inductance results in lowered efficiency.