Low power, less occupying area, and improved speed of a 4-bit router/rerouter circuit for low-density parity-check (LDPC) decoders

Background: Low-density parity-check (LDPC) codes are more error-resistant than other forward error-correcting codes. Existing circuits give high power dissipation, less speed, and more occupying area. This work aimed to propose a better design and performance circuit, even in the presence of noise in the channel. Methods: In this research, the design of the multiplexer and demultiplexer were achieved using pass transistor logic. The target parameters were low power dissipation, improved throughput, and more negligible delay with a minimum area. One of the essential connecting circuits in a decoShder architecture is a multiplexer (MUX) and a demultiplexer (DEMUX) circuit. The design of the MUX and DEMUX contributes significantly to the performance of the decoder. The aim of this paper was the design of a 4 × 1 MUX to route the data bits received from the bit update blocks to the parallel adder circuits and a 1 × 4 DEMUX to receive the input bits from the parallel adder and distribute the output to the bit update blocks in a layered architecture LDPC decoder. The design uses pass transistor logic and achieves the reduction of the number of transistors used. The proposed circuit was designed using the Mentor Graphics CAD tool for 180 nm technology. Results: The parameters of power dissipation, area, and delay were considered crucial parameters for a low power decoder. The circuits were simulated using computer-aided design (CAD) tools, and the results depicted a significantly low power dissipation of 7.06 nW and 5.16 nW for the multiplexer and demultiplexer, respectively. The delay was found to be 100.5 ns (MUX) and 80 ns (DEMUX). Conclusion: This decoder’s potential use may be in low-power communication circuits such as handheld devices and Internet of Things (IoT) circuits.

A Decoder – Look up Tables for FPGAs

The FPGA (Field-Programmable Gate Array) has recently become the popular hardware and so-called LUTs (Look up Tables) are the basic of the FPGAs logic. For example, n-LUT is the MOS pass transistors multiplexer 2n-1 which input data receive SRAM cells logic function configuration (user’s projects Truth Table). Address inputs of the LUT are the variables. Therefore, we get one n-arguments logic function for the actual FPGA configuration. To get m functions (even with the same n-arguments) we should take m LUT. Authors propose a novel Decoder n-LUT (n-DC LUT), which makes possible to get m functions with the same n-arguments, like in Program Logic Array (PLA) CPLD (Complex Programmable Logic Device). DC LUT activates one of the 2n product terms outputs. Combined with OR product terms we can get m functions with the same n-arguments. To do this option we can use, for example, FPGAs typical connections units. The restriction of Meade-Conway for the FPGAs allows n=3 in one tree. Two 3-LUTs with one 1-LUTs form 4-LUT. Modern Adaptive Logic Modules (ALM) have n=8, but not all possible functions are implemented. The article deals with the design and investigation of some variants 3-DC LUT: with pull up output resistors, with orthogonal output circuits, with orthogonal transistors for each pass transistor. Simulation confirms the feasibility of the proposed method and shows that DC LUT with orthogonal output circuits is better variant of the systems realization in terms of current consumption and time delay at large n. A further development of the ALM concept may be the introduction of adaptive DC LUT, which, by tuning, can calculate single LUT function or 2n decoder functions. The proposed elements allow to increase the functionality of the FPGAs.

Performance Analysis of a Low Power High Speed Hybrid Full Adder Circuit and Full Subtractor Circuit

In this paper, a hybrid 1-bit adder and 1-bit Subtractor designs are implemented. The hybrid adder circuit is constructed using CMOS (complementary metal oxide semiconductor) logic along with pass transistor logic. The design can be extended 16 and 32 bits lately. The proposed full adder circuit is compared with the existing conventional adders in terms of power, delay and area in order to obtain a better circuit that serves the present day needs of people. The existing 1-bit hybrid adder uses EXNOR logic combined with the transmission gate logic. For a supply voltage of 1.8V the average power consumption (4.1563 µW) which is extremely low with moderately low delay (224 ps) resulting because of the deliberate incorporation of very weak CMOS inverters coupled with strong transmission gates. At 1.2V supply the power and delay were recorded to be 1.17664 µW and 91.3 ps. The design was implemented using 1-bit which can also be extended into a 32-bit design later. The designed implementation offers a better performance in terms of power and speed compared to the existing full adder design styles. The circuits were implemented in DSCH2 and Microwind tools respectively. The parameters such as power, delay, layout area and speed of the proposed circuit design is compared with pass transistor logic, adiabatic logic, transmission gate adder and so on. The circuit is also designed with a decrease in transistors in order to get the better results. Full Subtractor, a combinational digital circuit which performs 1-bit subtraction with borrow in is designed as a part of this project. The main aim behind this part of the project is to design a 1-bit full Subtractor using CMOS technology with reduced number of transistors and hence the efficiency in terms of area, power and speed have been calculated is designed using 8,10,15and 16 transistors. The parameters were calculated in each case and the results have been tabulated.

Performance Analysis of a Low Power High Speed Hybrid Full Adder Circuit and Full Subtractor Circuit

In this paper, a hybrid 1-bit adder and 1-bit Subtractor designs are implemented. The hybrid adder circuit is constructed using CMOS (complementary metal oxide semiconductor) logic along with pass transistor logic. The design can be extended 16 and 32 bits lately. The proposed full adder circuit is compared with the existing conventional adders in terms of power, delay and area in order to obtain a better circuit that serves the present day needs of people. The existing 1-bit hybrid adder uses EXNOR logic combined with the transmission gate logic. For a supply voltage of 1.8V the average power consumption (4.1563 µW) which is extremely low with moderately low delay (224 ps) resulting because of the deliberate incorporation of very weak CMOS inverters coupled with strong transmission gates. At 1.2V supply the power and delay were recorded to be 1.17664 µW and 91.3 ps. The design was implemented using 1-bit which can also be extended into a 32-bit design later. The designed implementation offers a better performance in terms of power and speed compared to the existing full adder design styles. The circuits were implemented in DSCH2 and Microwind tools respectively. The parameters such as power, delay, layout area and speed of the proposed circuit design is compared with pass transistor logic, adiabatic logic, transmission gate adder and so on. The circuit is also designed with a decrease in transistors in order to get the better results. Full Subtractor, a combinational digital circuit which performs 1-bit subtraction with borrow in is designed as a part of this project. The main aim behind this part of the project is to design a 1-bit full Subtractor using CMOS technology with reduced number of transistors and hence the efficiency in terms of area, power and speed have been calculated is designed using 8,10,15and 16 transistors. The parameters were calculated in each case and the results have been tabulated.

Design a Low Power and High Speed 130nm Fulladder using Exclusive-OR and Exclusive NOR Gates

This literature illustrates the high speed and low power Full Adder (FADD) designs. This study relates to the composited structure of FADD design composed in one unit. In this the EXCL-OR/EXCL-NOR designs are used to design the FADD. Mostly concentrates on high speed standard FADD structure by combining the EXCL-OR/EXCL-NOR design in single unit. We implemented two composite structures of FADD through the full swing EXCL-OR/EXCL-NOR designs. And the EXCL-OR/EXCL-NOR design is done through pass transistor logic (PTL) and the same design projected on the composited FADD design. Such that the delay, area of the design, power requirement for the circuit gets optimized. The two composited FADD designs are compared and reduced the constraints of power requirement, area, delay and the power delay product (PDP). The simulated outcomes are verified through 130nnm CMOS mentor graphics tool.