The minimum operating voltage (VDDmin) of 90-nm CMOS ring oscillators (RO’s) is investigated in order to clarify the lower limit of supply voltage (VDD) for logic circuits. The measured VDDmin is determined by the intra-die threshold voltage random variations and increased from 91 mV to 224 mV when the number of RO stages increased from 11 to 1001, which hinders the VDD scaling. Lowering VDDmin...

An on-chip voltage supply regulator for subthreshold-operated CMOS logic LSIs is proposed. The regulator transforms lithium battery voltage 3 V to low supply voltage 0.4-0.5 V for subthreshold-operated CMOS logic LSIs. It monitors the gate delay in the LSI and produces an appropriate supply voltage such that the delay is equal to a value determined by a built-in capacitor-resistor reference. We...

In this work a low power, low voltage and high gain operational amplifier is proposed. For this purpose a negative resistance structure is used in parallel with output to improve the achievable gain. Because of using self cascode transistors in the output, the proposed structure remains approximately constant in a relatively large output voltage swing causing an invariable gain. To evaluate the...

To achieve the most energy-efficient operation, this brief presents a circuit design technique for separating the power supply voltage (VDD) of flip-flops (FFs) from that of combinational circuits, called the higher voltage FF (HVFF). Although VDD scaling can reduce the energy, the minimum operating voltage (VDDmin) of FFs prevents the operation at the optimum supply voltage that minimizes the ...

In this letter, a new cross-coupled charge pump for negative high voltage generation has been proposed. The problem of shoot-through current in the conventional cross-coupled charge pump is solved by a four clock phase scheme. By switching the power supply to each stage based on the supply voltage, a variable voltage gain is obtained. A complete analysis of the interaction between the power eff...

This paper introduces a high precise direct current (DC) negative high voltage power supply. The supply’s output voltage is 25kV and its maximal output current is 100mA. The power supply uses BOOST converter for power factor correction and voltage regulation. It converts DC to high frequency (HF) alternating current (AC) square wave with phase-shifted full bridge. The voltage of the AC square w...

Power dissipation in digital circuits has become a primary concern in electronic design. With increasing usage of portable devices, there are severe restrictions being placed on the size, weight and power of batteries. In this work, we propose a design of a dual Vth feedback type four-transistor level converter (DVF4) with reduced delay and power overheads. The use of DVF4 enhances the effectiv...

The use of the average-current-mode control in the recently introduced two-input buck postregulator is studied in this paper. Using this type of control, the attenuation of the input voltage ripple (100–120 Hz) increases in relation to the one obtained when a conventional voltage-mode control (with or without feedforward) is used and, therefore, lower bulk capacitors can be used to obtain a ver...

Recently low-voltage and low-noise analog circuits with sub100nm CMOS devices are strongly demanded for implementing mobile digital multimedia and wireless systems. Reduction of supply voltage makes it difficult to attain a signal voltage swing, and device deviation causes large DC offset voltage and 1/f noise. This paper describes noise reduction technique for CMOS analog and RF circuits opera...

Cold cathode fluorescent lamps (CCFLs) are commonly used as a backlight source for color liquid crystal displays (LCDs) used in notebook computers and portable electronic devices. These lamps require a high ac voltage for ignition and operation. The required ignition voltage is typically double the operating voltage and increases at cold temperatures. Figure 1 shows the operating voltage of lam...