A 555/690 Msps 4-bit Cmos Flash Adc Using Tiq Comparator

The real world signals are all analog in nature. So in order to convert the analog signals to digital efficiently an “Analog to digital converter” is required. In the digital domain, low power and low voltage requirements are becoming more important issues as the channel length of MOSFET shrinks below 0.25 sub-micron values. These trends present new challenges in ADC circuit design. In this paper, a novel flash analog-to-digital converter for low-power & high speed applications has been proposed by incorporating the threshold inverter quantization technique. The key idea of this technique is to generate 2 n – 1 different sized threshold inverter quantization comparators for an n-bit converter due to which the fast data conversion speed improves the operating speed and the elimination of ladder resistors leads significant reduction in the power consumption. The use of two cascaded inverters as a voltage comparator is the reason for the technique's name (TIQ). The gain boosters make sharper thresholds for comparator outputs and provide a full digital output voltage swing. The comparator outputs the thermometer code are converted to a binary code in two steps through the `01' generator and the encoder. The proposed 4 bit flash ADC using TIQ is designed using FAT tree encoder and simulated with the help of TANNER-EDA tool in 0.25 μm CMOS technology. This paper represents 4-bit flash ADC for supply voltage of 2.5Vand 3.3 V. Also transistor sizes are varied from 1.5μm to 12.1μm for different widths, for input frequency of 1 MHz and speed and power for different variation are estimated. The optimum values of Power and Speed are being chosen amongst the obtained value.